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Background: Breakthrough infections after SARS-CoV-2 vaccination have been reported. Clinical outcomes in these persons are not widely known. Methods: We evaluated all vaccinated persons with breakthrough infection ≥14 days after the second vaccine dose and unvaccinated controls matched on age, sex, nationality, and reason for testing between December 23, 2020 and March 28, 2021 in Qatar. Our primary outcome was severe disease defined as hospitalization, mechanical ventilation, or death. Results: Among 456 persons cases of breakthrough infection and 456 unvaccinated matched controls with confirmed infection, median age was 45 years, 60.7% were males, and ≥1 comorbid condition was present in 61.2% of the vaccinated and 47.8% of the unvaccinated persons (P=0.009). Severe disease was recorded in 48 (10.5%) of the vaccinated and 121 (26.5%) of the unvaccinated group (P40–60 years, HR 2.32; >60–70 years, HR 4.34; >70 years, HR 5.43); presence of symptoms at baseline (HR 2.42, 95%CI 1.44-4.07); and being unvaccinated (HR 2.84, 95%CI 1.80-4.47). Conclusions: In persons with breakthrough SARS-CoV-2 infection, increasing age is associated with a higher risk of severe disease or death, while vaccination is associated with a lower risk. Presence of comorbidities was not associated with severe disease or death among persons with breakthrough infection.

We investigated what proportion of the population acquired severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and whether the herd immunity threshold has been reached in 10 communities in Qatar. The study included 4,970 participants during June 21–September 9, 2020. Antibodies against SARS-CoV-2 were detected by using an electrochemiluminescence immunoassay. Seropositivity ranged from 54.9% (95% CI 50.2%–59.4%) to 83.8% (95% CI 79.1%–87.7%) across communities and showed a pooled mean of 66.1% (95% CI 61.5%–70.6%). A range of other epidemiologic measures indicated that active infection is rare, with limited if any sustainable infection transmission for clusters to occur. Only 5 infections were ever severe and 1 was critical in these young communities; infection severity rate of 0.2% (95% CI 0.1%–0.4%). Specific communities in Qatar have or nearly reached herd immunity for SARS-CoV-2 infection: 65%–70% of the population has been infected.

Highlights • Performances of five commercial ELISA (EDI, AnshLabs, Dia.Pro, NovaTec, and Lionex) for detecting anti-SARS-CoV-2 IgG was evaluated. • Samples used in this study are from diverse national background and the negative group contains samples that are seropositive for all other HCoV. • All assays showed low sensitivity during the early stages (≤7 from symptom onset); however, it was greatly improved overtime. • Lionex showed the highest specificity (98.6%), followed by EDI and Dia.Pro (97.1%,), NovaTec (85.7%), and AnshLabs (75.7%). • Lionex, which measures antibodies to the S1 protein, demonstrated the best performance and doesn’t cross-react with any other HCoV., Objectives To evaluate and compare the performances of five commercial ELISA assays (EDI, AnshLabs, Dia.Pro, NovaTec, and Lionex) for detecting anti-SARS-CoV-2 IgG. Methods 70 negative control samples (collected before the COVID-19 pandemic) and samples from 101 RT-PCR-confirmed SARS-CoV-2 patients (collected at different time points from symptoms onset: ≤7, 8-14, and >14 days) were used to compare the sensitivity, specificity, agreement, positive and negative predictive values of each assay with RT-PCR. A concordance assessment between the five assays was also conducted. Cross-reactivity with other HCoV, non-HCoV respiratory viruses, non-respiratory viruses, and nuclear antigens was investigated. Results Lionex showed the highest specificity (98.6%, 95%CI: 92.3-99.8), followed by EDI and Dia.Pro (97.1%, 95%CI: 90.2-99.2), NovaTec (85.7%, 95%CI: 75.7-92.1), then AnshLabs (75.7%, 95%CI: 64.5-84.2). All ELISA kits cross-reacted with one anti-MERS IgG positive sample except Lionex. The sensitivity was low during the early stages of the disease but improved over time. After 14 days from symptoms onset, Lionex and NovaTec showed the highest sensitivity at 87.9% (95%CI: 72.7-95.2) and 86.4% (95%CI: 78.5-91.7), respectively. The agreement with RT-PCR results based on Cohen’s kappa was as follows: Lionex (0.89)> NovaTec (0.70)> Dia.Pro (0.69)> AnshLabs (0.63)> EDI (0.55). Conclusion The Lionex ELISA, which measures antibodies solely to the S1 protein, demonstrated the best performance.

BACKGROUND: SARS-CoV-2 infection in pregnancy is associated with a higher risk of pregnancy-related complications and neonatal respiratory distress and hospitalization. Effectiveness of SARS-CoV-2 vaccines in pregnant women is not known. METHODS: All women with confirmed pregnancy who presented to the national referral hospital in Qatar between December 20, 2020, and May 30, 2021, with at least 1 SARS-CoV-2 test and not testing prior to pregnancy were included. We determined the vaccine effectiveness of mRNA vaccines in preventing confirmed SARS-CoV-2 infection during pregnancy using both cohort and test-negative case-control designs. Analyses were adjusted for age group, nationality, and gestational age. RESULTS: Among 4534 pregnant women, there were 407 vaccinated and 407 unvaccinated women in the matched cohort analysis. Vaccine effectiveness was 87.6% (95%CI 44.1%–97.2%) at least 14 days after the second dose. There were 386 test-positive and 834 matched women in the test-negative case control analysis. Vaccine effectiveness was 86.8% (95%CI 47.5%–98.5%) at least 14 days after the second dose. Adjustment for age, nationality, and gestational age yielded similar results for both designs. In the test-negative analysis, vaccine effectiveness at least 14 days after the first dose but before the second dose was 40.8% (95% CI 0.0%–80.4%). Of the 386 test-positive pregnant women, 74 cases were Alpha variant, 163 cases were Beta variant, and 156 cases were variants of unknown status. There were 9 severe or critical disease cases and no deaths in the test-positive pregnant women, all of whom were unvaccinated. CONCLUSION: The mRNA vaccines provide a high level of protection against documented SARS-CoV-2 infection, which supports the inclusion of pregnant women in vaccination campaigns. FUNDING: Hamad Medical Corporation, Weill Cornell Medicine Qatar, and the Ministry of Public Health Qatar.

The SARS-CoV-2 pandemic resulted in considerable morbidity and mortality as well as severe economic and societal disruptions. Despite scientific progress, true infection severity, factoring both diagnosed and undiagnosed infections, remains poorly understood. This study aimed to estimate SARS-CoV-2 age-stratified and overall morbidity and mortality rates based on analysis of extensive epidemiological data for the pervasive epidemic in Qatar, a country where

BackgroundWe investigated clinical outcomes of favipiravir in patients with COVID-19 pneumonia.MethodsPatients who between 23 May 2020 and 18 July 2020 received ≥24 hours of favipiravir were assigned to the favipiravir group, while those who did not formed the non-favipiravir group. The primary outcome was 28-day clinical improvement, defined as two-category improvement from baseline on an 8-point ordinal scale. Propensity scores (PS) for favipiravir therapy were used for 1:1 matching. Cox regression was used to examine associations with the primary endpoint.ResultsThe unmatched cohort included 1,493 patients, of which 51.7% were in the favipiravir group, and 48.3% were not receiving supplemental oxygen at baseline. Favipiravir was started within a median of 5 days from symptoms onset. Significant baseline differences between the two unmatched groups existed, but not between the PS-matched groups (N = 774). After PS-matching, there were no significant differences between the two groups in the proportion with 28-day clinical improvement (93.3% versus 92.8%, P 0.780), or 28-day all-cause mortality (2.1% versus 3.1%, P 0.360). Favipiravir was associated with more viral clearance by day 28 (79.8% versus 64.1%, P ConclusionFavipiravir therapy for COVID-19 pneumonia is well tolerated but is not associated with an increased likelihood of clinical improvement or reduced all-cause mortality by 28 days.

BACKGROUNDGrowing evidence suggests that COVID-19 vaccines differ in effectiveness against breakthrough infection or severe COVID-19, but vaccines have yet to be investigated in controlled studies that head-to-head compare immunity of one to another. This study compared protection offered by the mRNA-1273 (Moderna) vaccine with that of the BNT162b2 (Pfizer-BioNTech) vaccine in Qatar.METHODSIn a population of 1,531,736 vaccinated persons, two matched retrospective cohort studies were designed and used to investigate differences in mRNA-1273 and BNT162b2 vaccine protection, after the first and second doses, from December 21, 2020 to October 20, 2021.RESULTSAfter dose 1, cumulative incidence of breakthrough infection was 0.79% (95% CI: 0.75-0.83%) for mRNA-1273-vaccinated individuals and 0.86% (95% CI: 0.82-0.90%) for BNT162b2-vaccinated individuals, 21 days post-injection. Adjusted hazard ratio (AHR) for breakthrough infection was 0.89 (95% CI: 0.83-0.95; p=0.001). AHR was constant in the first two weeks at 1, but it declined to 0.67 (95% CI: 0.57-0.77; pCONCLUSIONSmRNA-1273 vaccination is associated with lower SARS-CoV-2 breakthrough infection and COVID-19 hospitalization and death than BNT162b2 vaccination, but the number of hospitalizations and deaths was exceedingly small for both vaccines. Both vaccines demonstrated strikingly similar patterns of build-up of protection after the first dose and waning of protection after the second dose.

Limited data are available regarding antimicrobial resistance in Neisseria gonorrhoeae strains circulating in WHO Eastern Mediterranean Region (EMR). We investigated the antimicrobial susceptibility/resistance of N. gonorrhoeae isolates to five antimicrobials (ceftriaxone, azithromycin, ciprofloxacin, tetracycline, and benzylpenicillin) currently or previously used for gonorrhoea treatment in Qatar, 2017-2020. Minimum inhibitory concentrations (MICs; mg/L) of antimicrobials were determined using Etest on gonococcal isolates collected during January 1, 2017-August 30, 2020 at Hamad Medical Corporation, a national public healthcare provider. During 2017-2020, resistance in isolates from urogenital sites of 433 patients was 64.7% (95% CI: 59.5-69.6%; range: 43.9-78.7%) for ciprofloxacin, 50.7% (95% CI: 45.3-56.1%; range: 41.3-70.4%) for tetracycline, and 30.8% (95% CI: 26.3-35.6%; range: 26.7-35.8%) for benzylpenicillin. Percentage of isolates non-susceptible to azithromycin was 4.1% (95% CI: 2.0-7.4%; range: 2.7-4.8%) and all (100%) isolates were susceptible to ceftriaxone. Two (1.6%) isolates from 2019 and one (2.2%) isolate from 2020 had high-level resistance to azithromycin (MIC≥256 mg/L). Overall, 1.0% (4/418) of isolates had a ceftriaxone MIC of 0.25 mg/L, which is at the ceftriaxone susceptibility breakpoint (MIC≤0.25 mg/L). Treatment with ceftriaxone 250 mg plus azithromycin 1 g can continuously be recommended for gonorrhoea therapy in Qatar. Continued quality-assured gonococcal AMR surveillance is warranted in EMR.

Key messages and recommendations Thispopulation-based study documentsBNT162b2vaccine protection week-by-week after the first dose. 75% of protection against infection and disease is reached 15-21 daysafter the first dose. Protection increased most rapidly against hospitalization and death and slowest against B.1.351infection.While protection of one dose beyond 21 days could not be assessed, findings support delaying the second vaccinedosein situations of limited vaccine suppliesand high incidences.

Background Waning of vaccine protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or coronavirus disease 2019 (Covid-19) is a concern. The persistence of BNT162b2 (Pfizer–BioNTech) vaccine effectiveness against infection and disease in Qatar, where the B.1.351 (or beta) and B.1.617.2 (or delta) variants have dominated incidence and polymerase-chain-reaction testing is done on a mass scale, is unclear. Methods We used a matched test-negative, case–control study design to estimate vaccine effectiveness against any SARS-CoV-2 infection and against any severe, critical, or fatal case of Covid-19, from January 1 to September 5, 2021. Results Estimated BNT162b2 effectiveness against any SARS-CoV-2 infection was negligible in the first 2 weeks after the first dose. It increased to 36.8% (95% confidence interval [CI], 33.2 to 40.2) in the third week after the first dose and reached its peak at 77.5% (95% CI, 76.4 to 78.6) in the first month after the second dose. Effectiveness declined gradually thereafter, with the decline accelerating after the fourth month to reach approximately 20% in months 5 through 7 after the second dose. Effectiveness against symptomatic infection was higher than effectiveness against asymptomatic infection but waned similarly. Variant-specific effectiveness waned in the same pattern. Effectiveness against any severe, critical, or fatal case of Covid-19 increased rapidly to 66.1% (95% CI, 56.8 to 73.5) by the third week after the first dose and reached 96% or higher in the first 2 months after the second dose; effectiveness persisted at approximately this level for 6 months. Conclusions BNT162b2-induced protection against SARS-CoV-2 infection appeared to wane rapidly following its peak after the second dose, but protection against hospitalization and death persisted at a robust level for 6 months after the second dose. (Funded by Weill Cornell Medicine–Qatar and others.)

BACKGROUNDWaning of vaccine protection against SARS-CoV-2 infection or COVID-19 disease is a concern. This study investigated persistence of BNT162b2 (Pfizer-BioNTech) vaccine effectiveness against infection and disease in Qatar, where the Beta and Delta variants have dominated incidence and PCR testing is done at a mass scale.METHODSA matched test-negative, case-control study design was used to estimate vaccine effectiveness against SARS-CoV-2 infection and against any severe, critical, or fatal COVID-19 disease, between January 1, 2021 to August 15, 2021.RESULTSEstimated BNT162b2 effectiveness against any infection, asymptomatic or symptomatic, was negligible for the first two weeks after the first dose, increased to 36.5% (95% CI: 33.1-39.8) in the third week after the first dose, and reached its peak at 72.1% (95% CI: 70.9-73.2) in the first five weeks after the second dose. Effectiveness declined gradually thereafter, with the decline accelerating ≥15 weeks after the second dose, reaching diminished levels of protection by the 20thweek. Effectiveness against symptomatic infection was higher than against asymptomatic infection, but still waned in the same fashion. Effectiveness against any severe, critical, or fatal disease increased rapidly to 67.7% (95% CI: 59.1-74.7) by the third week after the first dose, and reached 95.4% (95% CI: 93.4-96.9) in the first five weeks after the second dose, where it persisted at about this level for six months.CONCLUSIONSBNT162b2-induced protection against infection appears to wane rapidly after its peak right after the second dose, but it persists at a robust level against hospitalization and death for at least six months following the second dose.

With the global expansion of the highly transmissible SARS-CoV-2 Delta (B.1.617.2) variant, we conducted a matched test-negative case–control study to assess the real-world effectiveness of COVID-19 messenger RNA vaccines against infection with Delta in Qatar’s population. BNT162b2 effectiveness against any, symptomatic or asymptomatic, Delta infection was 45.3% (95% CI, 22.0–61.6%) ≥14 d after the first vaccine dose, but only 51.9% (95% CI, 47.0–56.4%) ≥14 d after the second dose, with 50% of fully vaccinated individuals receiving their second dose before 11 May 2021. Corresponding mRNA-1273 effectiveness ≥14 d after the first or second dose was 73.7% (95% CI, 58.1–83.5%) and 73.1% (95% CI, 67.5–77.8%), respectively. Notably, effectiveness against Delta-induced severe, critical or fatal disease was 93.4% (95% CI, 85.4–97.0%) for BNT162b2 and 96.1% (95% CI, 71.6–99.5%) for mRNA-1273 ≥ 14 d after the second dose. Our findings show robust effectiveness for both BNT162b2 and mRNA-1273 in preventing Delta hospitalization and death in Qatar’s population, despite lower effectiveness in preventing infection, particularly for the BNT162b2 vaccine. mRNA COVID-19 vaccines are highly effective at preventing severe outcomes and death caused by the SARS-CoV-2 Delta variant (B.1.617.2) in Qatar despite substantially lower effectiveness at blocking infection.

Severity (acute-care hospitalization), criticality (ICU hospitalization), and fatality of SARS-CoV-2 Beta (B.1.351) variant was investigated through case-control studies applied to complete national cohorts of infection, disease, and death cases in Qatar. Compared to Alpha (B.1.1.7) variant, odds of progressing to severe disease were 1.24-fold (95% CI: 1.11-1.39) higher for Beta. Odds of progressing to critical disease were 1.49-fold (95% CI: 1.13-1.97) higher. Odds of COVID-19 death were 1.57-fold (95% CI: 1.03-2.43) higher. Findings highlight risks to healthcare systems, particularly to intensive care facilities and resources, with increased circulation of Beta.

Beta (B.1.351)–variant coronavirus disease 2019 (COVID-19) disease was investigated in Qatar. Compared with the Alpha (B.1.1.7) variant, odds (95% confidence interval) of progressing to severe disease, critical disease, and COVID-19–related death were 1.24-fold (1.11–1.39), 1.49-fold (1.13–1.97), and 1.57-fold (1.03–2.43) higher, respectively, for the Beta variant.

SARS-CoV-2 breakthrough infections in vaccinated individuals and in those who had a prior infection have been observed globally, but the transmission potential of these infections is unknown. The RT-qPCR cycle threshold (Ct) value is inversely correlated with viral load and culturable virus. Here, we investigated differences in RT-qPCR Ct values across Qatar’s national cohorts of primary infections, reinfections, BNT162b2 (Pfizer-BioNTech) breakthrough infections, and mRNA-1273 (Moderna) breakthrough infections. Through matched-cohort analyses of the randomly diagnosed infections, the mean Ct value was higher in all cohorts of breakthrough infections compared to the cohort of primary infections in unvaccinated individuals. The Ct value was 1.3 (95% CI: 0.9-1.8) cycles higher for BNT162b2 breakthrough infections, 3.2 (95% CI: 1.8-4.5) cycles higher for mRNA-1273 breakthrough infections, and 4.0 (95% CI: 3.4-4.6) cycles higher for reinfections in unvaccinated individuals. Assuming a linear relationship between viral load and infectiousness, these differences imply that breakthrough infections are at least 50% less infectious than primary infections in unvaccinated individuals. Public health benefits of vaccination may have been underestimated, as COVID-19 vaccines not only protect against acquisition of infection, but also appear to protect against transmission of infection.

Effect of prior SARS-CoV-2 infection on vaccine protection remains poorly understood. Here, we investigated whether persons vaccinated after a prior infection have better protection against future infection than those vaccinated without prior infection. Effect of prior infection was assessed in Qatar’s population, where the Alpha (B.1.1.7) and Beta (B.1.351) variants dominate incidence, using two national retrospective, matched-cohort studies, one for the BNT162b2 (Pfizer-BioNTech) vaccine, and one for the mRNA-1273 (Moderna) vaccine. Incidence rates of infection among BNT162b2-vaccinated persons, with and without prior infection, were estimated, respectively, at 1.66 (95% CI: 1.26-2.18) and 11.02 (95% CI: 9.90-12.26) per 10,000 person-weeks. The incidence rate ratio was 0.15 (95% CI: 0.11-0.20). Analogous incidence rates among mRNA-1273-vaccinated persons were estimated at 1.55 (95% CI: 0.86-2.80) and 1.83 (95% CI: 1.07-3.16) per 10,000 person-weeks. The incidence rate ratio was 0.85 (95% CI: 0.34-2.05). Prior infection enhanced protection of those BNT162b2-vaccinated, but not those mRNA-1273-vaccinated. These findings may have implications for dosing, interval between doses, and potential need for booster vaccination.

The SARS-CoV-2 pandemic continues to be a global health concern. The mRNA-1273 (Moderna) vaccine was reported to have an efficacy of 94.1% at preventing symptomatic COVID-19 due to infection with ‘wild-type’ variants in a randomized clinical trial. Here, we assess the real-world effectiveness of this vaccine against SARS-CoV-2 variants of concern, specifically B.1.1.7 (Alpha) and B.1.351 (Beta), in Qatar, a population that comprises mainly working-age adults, using a matched test-negative, case-control study design. We show that vaccine effectiveness was negligible for 2 weeks after the first dose, but increased rapidly in the third and fourth weeks immediately before administration of a second dose. Effectiveness against B.1.1.7 infection was 88.1% (95% confidence interval (CI): 83.7–91.5%) ≥14 days after the first dose but before the second dose, and was 100% (95% CI: 91.8–100.0%) ≥14 days after the second dose. Analogous effectiveness against B.1.351 infection was 61.3% after the first dose (95% CI: 56.5–65.5%) and 96.4% after the second dose (95% CI: 91.9–98.7%). Effectiveness against any severe, critical or fatal COVID-19 disease due to any SARS-CoV-2 infection (predominantly B.1.1.7 and B.1.351) was 81.6% (95% CI: 71.0–88.8%) and 95.7% (95% CI: 73.4–99.9%) after the first and second dose, respectively. The mRNA-1273 vaccine is highly effective against B.1.1.7 and B.1.351 infections, whether symptomatic or asymptomatic, and against any COVID-19 hospitalization and death, even after a single dose. A matched test-negative, case-control study using real-world data from a predominantly working-age population demonstrates efficacy of the mRNA-1273 vaccine to be 100% and 96.4% against the B.1.1.7 (Alpha) and B.1.351 (Beta) SARS-CoV-2 variants of concern, respectively.

Pregnancy may increase the risk of adverse maternal and neonatal outcomes in SARS-CoV-2 infection. Effectiveness of SARS-CoV-2 vaccines in pregnant women is not known. Using a test-negative case-control study, we determined the vaccine effectiveness of mRNA vaccines in preventing confirmed SARS-CoV-2 infection in pregnant women at a national referral hospital, which handles > 75% of the deliveries in Qatar. Among 2,020 pregnant women who met the study criteria, 397 had a positive SARS-CoV-2 RT-PCR and 1,623 had a negative test. Vaccine effectiveness ≥ 14 days after the second dose was 67.7% (95%CI 30.5–86.9), while vaccine effectiveness ≥ 14 days after the first dose but before the second dose was 40.3% (95%CI 0.0-80.4). There were nine severe/critical disease cases, and no deaths in the PCR-positive pregnant women, all among unvaccinated. The mRNA vaccines provide high level of protection against documented SARS-CoV-2 infection, which supports including pregnant women in vaccination campaigns.

BACKGROUND Cryptococcosis is a major opportunistic invasive mycosis that mostly affects immunocompromised patients. METHODS This was an observational study of all culture-confirmed cases of cryptococcosis conducted in the State of Qatar from January 2005 to December 2016. Cryptococcus fungi were identified using Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS). RESULTS Fourteen culture-confirmed cases of cryptococcosis were identified during the study period. Four patients had a Human Immunodeficiency Virus (HIV) infection with low CD4 count and five were receiving immunosuppressant medications. The rest of the patients were apparently immuno-competent. The central nervous system was the most common site of infection (57%) followed by bloodstream infection (36%) and pneumonia (14%). One patient had a cryptococcal scrotal infection. Twelve isolates were Cryptococcus neoformans and 2 were Cryptococcus laurentii. All isolates were within the wild type ECV values to amphotericin B and fluconazole. Only 2 patients with bloodstream infection (HIV negative) died. The rest were cured of the infection. CONCLUSION Cryptococcosis is a rare fungal disease in the State of Qatar, mostly diagnosed in Asian immigrants. The central nervous system is the most common site of infection. The presence of the fungus in the blood carries a high mortality.

Background Qatar experienced a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic that disproportionately affected the craft and manual worker (CMW) population, who comprise 60% of the total population. This study aimed to assess ever and/or current infection prevalence in this population. Methods A cross-sectional population-based survey was conducted during July 26 to September 09, 2020, to assess both anti-SARS-CoV-2 positivity through serological testing and current infection positivity through polymerase chain reaction (PCR) testing. Associations with antibody and PCR positivity were identified through regression analyses. Results The study included 2641 participants, 69.3% of whom were Conclusions Six in every 10 CMWs in Qatar have been infected, suggestive of reaching the herd immunity threshold. Infection severity was low, with only 1 in every 200 infections progressing to be severe or critical. Only 1 in every 10 infections had been previously diagnosed, which is suggestive of mostly asymptomatic or mild infections.

Background Reinfection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been documented, raising public health concerns. SARS-CoV-2 reinfections were assessed in a cohort of antibody-positive persons in Qatar. MethodsAll SARS-CoV-2 antibody-positive persons from April 16 to December 31, 2020 with a PCR-positive swab ≥14 days after the first-positive antibody test were investigated for evidence of reinfection. Viral genome sequencing was conducted for paired viral specimens to confirm reinfection. Incidence of reinfection was compared to incidence of infection in the complement cohort of those who were antibody-negative. FindingsAmong 43,044 antibody-positive persons who were followed for a median of 16.3 weeks (range: 0–34.6), 314 individuals (0.7%) had at least one PCR positive swab ≥14 days after the first-positive antibody test. Of these individuals, 129 (41.1%) had supporting epidemiological evidence for reinfection. Reinfection was next investigated using viral genome sequencing. Applying the viral-genome-sequencing confirmation rate, the incidence rate of reinfection was estimated at 0.66 per 10,000 person-weeks (95% CI: 0.56–0.78). Incidence rate of reinfection versus month of follow-up did not show any evidence of waning of immunity for over seven months of follow-up. Meanwhile, in the complement cohort of 149,923 antibody-negative persons followed for a median of 17.0 weeks (range: 0–45.6), incidence rate of infection was estimated at 13.69 per 10,000 person-weeks (95% CI: 13.22–14.14). Efficacy of natural infection against reinfection was estimated at 95.2% (95% CI: 94.1–96.0%). Reinfections were less severe than primary infections. Only one reinfection was severe, two were moderate, and none were critical or fatal. Most reinfections (66.7%) were diagnosed incidentally through random or routine testing, or through contact tracing. InterpretationReinfection is rare in the young and international population of Qatar. Natural infection appears to elicit strong protection against reinfection with an efficacy ~95% for at least seven months. FundingBiomedical Research Program, the Biostatistics, Epidemiology, and Biomathematics Research Core, and the Genomics Core, all at Weill Cornell Medicine-Qatar, the Ministry of Public Health, Hamad Medical Corporation, and the Qatar Genome Programme. The authors are grateful for support from the Biomedical Research Program, the Biostatistics, Epidemiology, and Biomathematics Research Core, and the Genomics Core, all at Weill Cornell Medicine-Qatar, as well as for support provided by the Ministry of Public Health and Hamad Medical Corporation. The authors are also grateful for support from the Qatar Genome Programme for supporting the viral genome sequencing. The statements made herein are solely the responsibility of the authors.

Background Vaccines against SARS-CoV-2 have been developed, but their availability falls far short of global needs. This study aimed to investigate the impact of prioritising available doses on the basis of recipient antibody status, that is by exposure status, using Qatar as an example. Methods Vaccination impact (defined as the reduction in infection incidence and the number of vaccinations needed to avert one infection or one adverse disease outcome) was assessed under different scale-up scenarios using a deterministic meta-population mathematical model describing SARS-CoV-2 transmission and disease progression in the presence of vaccination. Results For a vaccine that protects against infection with an efficacy of 95%, half as many vaccinations were needed to avert one infection, disease outcome or death by prioritising antibody-negative individuals for vaccination. Prioritisation by antibody status reduced incidence at a faster rate and led to faster elimination of infection and return to normalcy. Further prioritisation by age group amplified the gains of prioritisation by antibody status. Gains from prioritisation by antibody status were largest in settings where the proportion of the population already infected at the commencement of vaccination was 30%-60%. For a vaccine that only protects against disease and not infection, vaccine impact was reduced by half, whether this impact was measured in terms of averted infections or disease outcomes, but the relative gains from using antibody status to prioritise vaccination recipients were similar. Conclusions Major health and economic gains can be achieved more quickly by prioritizing those who are antibody-negative while doses of the vaccine remain in short supply. This study received support from the Biomedical Research Program, and the Biostatistics, Epidemiology, and Biomathematics Research Core, all at Weill Cornell MedicineQatar, as well as support provided by the Ministry of Public Health and Hamad Medical Corporation. The developed mathematical models were made possible by NPRP grant number 9-040-3-008 (principal investigator: LJA-R) and NPRP grant number 12S-0216-190094 (principal investigator: LJA-R) from the Qatar National Research Fund (a member of Qatar Foundation; https://www.qnrf.org).

The heterogeneity of COVID-19 lies within its diverse symptoms and severity, ranging from mild to lethal. Acute respiratory distress syndrome (ARDS) has been shown to be the leading cause of mortality in COVID-19 patients, characterized by a hyper cytokine storm. Autoimmunity is proposed to occur as a result of COVID-19, given the high similarity of the immune responses observed in COVID-19 and autoimmune diseases. Here, we investigate the level of autoimmune antibodies in COVID-19 patients with different severities. Initial screening for antinuclear antibodies (ANA) IgG revealed that 1.6% (2/126) and 4% (5/126) of ICU COVID-19 cases developed strong and moderate ANA levels, respectively. However, all the non-ICU cases (n=273) were ANA negative. The high ANA level was confirmed by immunofluorescence (IFA) and large-scale autoantibody screening by phage immunoprecipitation-sequencing (PhIP-Seq). Indeed, the majority of the samples showed “speckled” ANA pattern by microscopy, and we demonstrate that samples of ICU patients with strong and moderate ANA levels contain autoantibody specificities that predominantly targeted proteins involved in intracellular signal transduction, metabolism, apoptotic processes, and cell death; further denoting reactivity to nuclear and cytoplasmic antigens. In conclusion, our results further support the notion of routine screening for autoimmune responses in COVID-19 patients, which might help improve disease prognosis and patient management. Further, results provide compelling evidence that ANA-positive individuals should be excluded from being donors for convalescent plasma therapy in the context of Covid-19.

BackgroundThe objective of this study was to develop a Coronavirus Disease 2019 (COVID-19) risk score to guide targeted RT-PCR testing in Qatar.MethodsThe Qatar national COVID-19 testing database was analyzed. This database includes a total of 2,688,232 RT-PCR tests conducted between February 5, 2020-January 27, 2021. Logistic regression analyses were implemented to identify predictors of infection and to derive the COVID-19 risk score, as a tool to identify those at highest risk of having the infection. Score cut-off was determined using the receiving operating characteristic (ROC) curve based on maximum sum of sensitivity and specificity. The score’s performance diagnostics were assessed.ResultsLogistic regression analysis identified age, sex, and nationality as significant predictors of infection and were included in the risk score. The score’s scoring points were lower for females compared to males and higher for specific nationalities. The ROC curve was generated and the area under the curve was estimated at 0.63 (95% CI: 0.63-0.63). The score had a sensitivity of 59.4% (95% CI: 59.1%-59.7%), specificity of 61.1% (95% CI: 61.1%-61.2%), a positive predictive value of 10.9% (95% CI: 10.8%-10.9%), and a negative predictive value of 94.9% (94.9%-95.0%). The risk score derived early in the epidemic, based on data until only April 21, 2020, had a performance comparable to that of a score based on a year-long testing.ConclusionsThe concept and utility of a COVID-19 risk score were demonstrated in Qatar. Such a public health tool, based on a set of non-invasive and easily captured variables can have considerable utility in optimizing testing and suppressing infection transmission, while maximizing efficiency and use of available resources.

COVID-19 complications present a huge burden on healthcare systems and warrant a predictive risk model for disease severity of SARS-CoV-2 infection to enable early intervention, prospective decision-making and triaging of patients. We profiled plasma proteins from COVID-19 patients (severe n=50, and mild n=50) and controls (n=50) using function- and pathway-based panels developed with the highly specific proximity extension assays. Several biological pathways were specific for patients with severe complications. Based on these dysregulated profiles, we propose candidate FDA-approved drugs that target multiple upregulated proteins to treat severe complications. In addition, the set of differentially expressed plasma proteins in severe disease contained a robust 46-protein signature, the COVID-19 molecular severity score, which predicts the risk of severe complications. We cross-validated this molecular severity score in an independent cohort and found it useful within three days after hospital admission to predict COVID-19 severity and outcomes. Associated with the molecular severity score, we identified a set of clinical parameters available at admission, that act as a clinical risk score for complications. The molecular and clinical risk scores described in our study may be prognostic tools for severe COVID-19 disease and help alleviate the pressure on healthcare systems during infection peaks.

ObjectiveTo investigate the performance of a rapid point-of-care antibody test, the BioMedomics COVID-19 IgM/IgG Rapid Test, in comparison with a high-quality, validated, laboratory-based platform, the Roche Elecsys Anti-SARS-CoV-2 assay.MethodsSerological testing was conducted on 708 individuals. Concordance metrics were estimated. Logistic regression was used to assess associations with seropositivity.ResultsSARS-CoV-2 seroprevalence was 63.4% (449/708; 95% CI 59.8%-66.9%) using the BioMedomics assay and 71.9% (509/708; 95% CI 68.5%-75.1%) using the Elecsys assay. There were 62 discordant results between the two assays. One specimen was seropositive in the BioMedomics assay, but seronegative in the Elecsys assay, while 61 specimens were seropositive in the Elecsys assay, but seronegative in the BioMedomics assay. Positive, negative, and overall percent agreements between the two assays were 88.0% (95% CI 84.9%-90.6%), 99.5% (95% CI 97.2%-99.9%), and 91.2% (95% CI 88.9%-93.1%), respectively, with a Cohen’s kappa of 0.80 (95% CI 0.77-0.83), indicating excellent agreement. Excluding specimens with lower antibody titers, the agreement improved with positive, negative, and overall percent concordance of 91.2% (95% CI 88.2%-93.6%), 99.5% (95% CI 97.2%-99.9%), and 93.9% (95% CI 91.7%-95.5%), respectively, and a Cohen’s kappa of 0.87 (95% CI 0.84-0.89). Logistic regression confirmed better agreement with higher antibody titers.ConclusionThe BioMedomics COVID-19 IgM/IgG Rapid Test demonstrated excellent performance in measuring detectable antibodies against SARS-CoV-2, supporting the utility of such rapid point-of-care serological testing to guide the public health responses and possible vaccine prioritization.

BackgroundReinfection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been documented, raising public health concerns. Risk and incidence rate of SARS-CoV-2 reinfection were assessed in a large cohort of antibody-positive persons in Qatar.MethodsAll SARS-CoV-2 antibody-positive persons with a PCR-positive swab ≥14 days after the first-positive antibody test were individually investigated for evidence of reinfection. Viral genome sequencing was conducted for paired viral specimens to confirm reinfection. Incidence of reinfection was compared to incidence of infection in the complement cohort of those antibody-negative.ResultsAmong 43,044 anti-SARS-CoV-2 positive persons who were followed for a median of 16.3 weeks (range: 0-34.6), 314 individuals (0.7%) had at least one PCR positive swab ≥14 days after the first-positive antibody test. Of these individuals, 129 (41.1%) had supporting epidemiological evidence for reinfection. Reinfection was next investigated using viral genome sequencing. Applying the viral-genome-sequencing confirmation rate, the risk of reinfection was estimated at 0.10% (95% CI: 0.08-0.11%). The incidence rate of reinfection was estimated at 0.66 per 10,000 person-weeks (95% CI: 0.56-0.78). Incidence rate of reinfection versus month of follow-up did not show any evidence of waning of immunity for over seven months of follow-up. Meanwhile, in the complement cohort of 149,923 antibody-negative persons followed for a median of 17.0 weeks (range: 0-45.6), risk of infection was estimated at 2.15% (95% CI: 2.08-2.22%) and incidence rate of infection was estimated at 13.69 per 10,000 person-weeks (95% CI: 13.22-14.14). Efficacy of natural infection against reinfection was estimated at 95.2% (95% CI: 94.1-96.0%). Reinfections were less severe than primary infections. Only one reinfection was severe, two were moderate, and none were critical or fatal. Most reinfections (66.7%) were diagnosed incidentally through random or routine testing, or through contact tracing.ConclusionsReinfection is rare. Natural infection appears to elicit strong protection against reinfection with an efficacy ∼95% for at least seven months.

BackgroundQatar has experienced a large SARS-CoV-2 epidemic. Our first objective was to assess the proportion of the urban population that has been infected with SARS-CoV-2, by measuring the prevalence of detectable antibodies. Our second objective was to identify predictors for infection and for having higher antibody titers.MethodsResidual blood specimens from individuals receiving routine and other clinical care between May 12-September 9, 2020 were tested for anti-SARS-CoV-2 antibodies. Associations with seropositivity and higher antibody titers were identified through regression analyses. Probability weights were applied in deriving the epidemiological measures.ResultsWe tested 112,941 individuals (∼10% of Qatar’s urban population), of whom 51.6% were men and 66.0% were 20-49 years of age. Seropositivity was 13.3% (95% CI: 13.1-13.6%) and was significantly associated with sex, age, nationality, clinical-care type, and testing date. The proportion with higher antibody titers varied by age, nationality, clinical-care type, and testing date. There was a strong correlation between higher antibody titers and seroprevalence in each nationality, with a Pearson correlation coefficient of 0.85 (95% CI: 0.47-0.96), suggesting that higher antibody titers may indicate repeated exposure to the virus. The percentage of antibody-positive persons with prior PCR-confirmed diagnosis was 47.1% (95% CI: 46.1-48.2%), severity rate was 3.9% (95% CI: 3.7-4.2%), criticality rate was 1.3% (95% CI: 1.1-1.4%), and fatality rate was 0.3% (95% CI: 0.2-0.3%).ConclusionsFewer than two in every 10 individuals in Qatar’s urban population had detectable antibodies against SARS-CoV-2 between May 12-September 9, 2020, suggesting that this population is still far from the herd immunity threshold and at risk from a subsequent epidemic wave.

Background: Mathematical modeling constitutes an important tool for planning robust responses to epidemics. This study was conducted to guide the Qatari national response to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic. The study investigated the epidemic's time-course, forecasted health care needs, predicted the impact of social and physical distancing restrictions, and rationalized and justified easing of restrictions. Methods: An age-structured deterministic model was constructed to describe SARS-CoV-2 transmission dynamics and disease progression throughout the population. Results: The enforced social and physical distancing interventions flattened the epidemic curve, reducing the peaks for incidence, prevalence, acute-care hospitalization, and intensive care unit (ICU) hospitalizations by 87%, 86%, 76%, and 78%, respectively. The daily number of new infections was predicted to peak at 12 750 on May 23, and active-infection prevalence was predicted to peak at 3.2% on May 25. Daily acute-care and ICU-care hospital admissions and occupancy were forecast accurately and precisely. By October 15, 2020, the basic reproduction number R0 had varied between 1.07-2.78, and 50.8% of the population were estimated to have been infected (1.43 million infections). The proportion of actual infections diagnosed was estimated at 11.6%. Applying the concept of Rt tuning, gradual easing of restrictions was rationalized and justified to start on June 15, 2020, when Rt declined to 0.7, to buffer the increased interpersonal contact with easing of restrictions and to minimize the risk of a second wave. No second wave has materialized as of October 15, 2020, five months after the epidemic peak. Conclusions: Use of modeling and forecasting to guide the national response proved to be a successful strategy, reducing the toll of the epidemic to a manageable level for the health care system.

BackgroundPerformance of three automated commercial serological IgG-based assays was investigated for assessing SARS-CoV-2 ever (past or current) infection in a population-based sample in a high exposure setting.MethodsPCR and serological testing was performed on 394 individuals.ResultsSARS-CoV-2-IgG seroprevalence was 42.9% (95% CI 38.1%-47.8%), 40.6% (95% CI 35.9%-45.5%), and 42.4% (95% CI 37.6%-47.3%) using the CL-900i, VidasIII, and Elecsys assays, respectively. Between the three assays, overall, positive, and negative percent agreements ranged between 93.2%-95.7%, 89.3%-92.8%, and 93.8%-97.8%, respectively; Cohen kappa statistic ranged from 0.86-0.91; and 35 specimens (8.9%) showed discordant results. Among all individuals, 12.5% (95% CI 9.6%-16.1%) had current infection, as assessed by PCR. Of these, only 34.7% (95% CI 22.9%-48.7%) were seropositive by at least one assay. A total of 216 individuals (54.8%; 95% CI 49.9%-59.7%) had evidence of ever infection using antibody testing and/or PCR during or prior to this study. Of these, only 78.2%, 74.1%, and 77.3% were seropositive in the CL-900i, VidasIII, and Elecsys assays, respectively.ConclusionsAll three assays had comparable performance and excellent agreement, but missed at least 20% of individuals with past or current infection. Commercial antibody assays can substantially underestimate ever infection, more so when infection rates are high.

Background Risk of reinfection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unknown. We assessed the risk and incidence rate of documented SARS-CoV-2 reinfection in a cohort of laboratory-confirmed cases in Qatar. Methods All SARS-CoV-2 laboratory-confirmed cases with at least 1 polymerase chain reaction–positive swab that was ≥45 days after a first positive swab were individually investigated for evidence of reinfection. Viral genome sequencing of the paired first positive and reinfection viral specimens was conducted to confirm reinfection. Results Out of 133 266 laboratory-confirmed SARS-CoV-2 cases, 243 persons (0.18%) had at least 1 subsequent positive swab ≥45 days after the first positive swab. Of these, 54 cases (22.2%) had strong or good evidence for reinfection. Median time between the first swab and reinfection swab was 64.5 days (range, 45–129). Twenty-three of the 54 cases (42.6%) were diagnosed at a health facility, suggesting presence of symptoms, while 31 (57.4%) were identified incidentally through random testing campaigns/surveys or contact tracing. Only 1 person was hospitalized at the time of reinfection but was discharged the next day. No deaths were recorded. Viral genome sequencing confirmed 4 reinfections of 12 cases with available genetic evidence. Reinfection risk was estimated at 0.02% (95% confidence interval [CI], .01%–.02%), and reinfection incidence rate was 0.36 (95% CI, .28–.47) per 10 000 person-weeks. Conclusions SARS-CoV-2 reinfection can occur but is a rare phenomenon suggestive of protective immunity against reinfection that lasts for at least a few months post primary infection.

BACKGROUND: We investigated the clinical characteristics and risk factors for the isolation of multi-drug-resistant (MDR) Gram-negative bacteria (GNB) from critically ill COVID-19 patients. METHODS: We retrospectively matched (1:2) critical COVID-19 patients with one or more MDR GNB from any clinical specimen (cases), with those with no MDR GNB isolates (controls). RESULTS: Seventy-eight cases were identified (4.5 per 1000 intensive care unit (ICU) days, 95% confidence interval (CI) 3.6-5.7). Of 98 MDR GNB isolates, the most frequent species were Stenotrophomonas maltophilia (24, 24.5%), and Klebsiella pneumoniae (23, 23.5%). Two (8.7%) K. pneumoniae, and six (85.7%) Pseudomonas aeruginosa isolates were carbapenem resistant. A total of 24 (24.5%) isolates were not considered to be associated with active infection. Those with active infection received appropriate antimicrobial agents within a median of one day. The case group had significantly longer median central venous line days, mechanical ventilation days, and hospital length of stay (P

BackgroundThis study aimed to estimate the age-stratified and overall morbidity and mortality rates of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection based on an analysis of the pervasive SARS-CoV-2 epidemic in Qatar, a country with MethodsInfection disease outcomes were investigated using a Bayesian approach applied to an age-structured mathematical model describing SARS-CoV-2 transmission and disease progression in the population. The model was fitted to infection and disease time-series and age-stratified data. Two separate criteria for classifying morbidity were used: one based on actual recorded hospital admission (acute-care or intensive-care-unit hospitalization) and one based on clinical presentation as per World Health Organization classification of disease severity or criticality.ResultsAll outcomes showed very strong age dependence, with low values for those ConclusionsSARS-CoV-2 severity and fatality in Qatar was not high and demonstrated a very strong age dependence with

BackgroundQatar experienced a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic that disproportionately affected the craft and manual worker (CMW) population who comprise 60% of the total population. This study aimed to assess the proportions of ever and/or current infection in this population.MethodsA cross-sectional population-based survey was conducted during July 26-September 09, 2020 to assess both anti-SARS-CoV-2 positivity through serological testing and polymerase chain reaction (PCR) positivity through PCR testing. Associations with antibody and PCR positivity were identified through regression analyses.ResultsStudy included 2,641 participants, 69.3% of whom were ConclusionsSix in every 10 CMWs have been infected, suggestive of reaching the herd immunity threshold. Infection severity was low with only one in every 200 infections progressing to be severe or critical. Only one in every 10 infections had been previously diagnosed suggestive of mostly asymptomatic or minimally mild infections.

BackgroundMathematical modeling constitutes an important tool for planning robust responses to epidemics. This study was conducted to guide the Qatari national response to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic. The study investigated the time course of the epidemic, forecasted healthcare needs, predicted the impact of social and physical distancing restrictions, and rationalized and justified easing of restrictions.MethodsAn age-structured deterministic model was constructed to describe SARS-CoV-2 transmission dynamics and disease progression throughout the population.ResultsThe enforced social and physical distancing interventions flattened the epidemic curve, reducing the peaks for incidence, prevalence, acute-care hospitalization, and intensive care unit (ICU) hospitalizations by 87%, 86%, 76%, and 78%, respectively. The daily number of new infections was predicted to peak at 12,750 on May 23, and active-infection prevalence was predicted to peak at 3.2% on May 25. Daily acute-care and ICU-care hospital admissions and occupancy were forecast accurately and precisely. By October 15, 2020, the basic reproduction number R0 had varied between 1.07-2.78, and 50.8% of the population were estimated to have been infected (1.43 million infections). The proportion of actual infections diagnosed was estimated at 11.6%. Applying the concept of Rt tuning, gradual easing of restrictions was rationalized and justified to start on June 15, 2020, when Rt declined to 0.7, to buffer the increased interpersonal contact with easing of restrictions and to minimize the risk of a second wave. No second wave has materialized as of October 15, 2020, five months after the epidemic peak.ConclusionsUse of modeling and forecasting to guide the national response proved to be a successful strategy, reducing the toll of the epidemic to a manageable level for the healthcare system.

The ongoing pandemic of SARS-COV-2 has already infected more than eight million people worldwide. The majority of COVID-19 patients either are asymptomatic or have mild symptoms. Yet, about 15% of the cases experience severe complications and require intensive care. Factors determining disease severity are not yet fully characterized. Here, we investigated the within-host virus diversity in COVID-19 patients with different clinical manifestations. We compared SARS-COV-2 genetic diversity in 19 mild and 27 severe cases. Viral RNA was extracted from nasopharyngeal samples and sequenced using the Illumina MiSeq platform. This was followed by deep-sequencing analyses of SARS-CoV-2 genomes at both consensus and sub-consensus sequence levels. Consensus sequences of all viruses were very similar, showing more than 99.8% sequence identity regardless of the disease severity. However, the sub-consensus analysis revealed significant differences in within-host diversity between mild and severe cases. Patients with severe symptoms exhibited a significantly (-value 0.001) higher number of variants in coding and non-coding regions compared to mild cases. Analysis also revealed higher prevalence of some variants among severe cases. Most importantly, severe cases exhibited significantly higher within-host diversity (mean = 13) compared to mild cases (mean = 6). Further, higher within-host diversity was observed in patients above the age of 60 compared to the younger age group. These observations provided evidence that within-host diversity might play a role in the development of severe disease outcomes in COVID-19 patients; however, further investigations are required to elucidate this association. This work was supported by Qatar University under internal grant (QUCG-BRC-20/21-1) and Qatar National Research Fund grant under grant (RRC-2-039).

The Middle East respiratory syndrome coronavirus (MERS-CoV) emerged in 2012. The objective of the study was to describe the epidemiology, risk factors, clinical characteristics, and outcome of MERS-CoV in Qatar. A total of 28 cases of MERS-CoV were identified, corresponding to an incidence of 1.7 per 1,000,000 population. Most patients had a history of contact with camels 15, travel to Kingdom of Saudi Arabia 7 or known contact with individuals with confirmed MERS-CoV infection 7. Majority of patients had acute kidney injury (AKI) 17 and 9 needed renal replacement therapy. All patients were hospitalized, 14 required critical care support. Overall, total of 10 died. The immediate cause of death was multiorgan failure with acute respiratory syndrome (ARDS) 9. MERS-CoV is a rare infection in the State of Qatar. There was no hospital outbreaks or healthcare worker reported infection. The infection causes severe respiratory failure and acute renal failure. Patients with AKI and on ventilator support carry higher risk of mortality.

BackgroundReinfection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is debated. We assessed risk and incidence rate of documented SARS-CoV-2 reinfection in a large cohort of laboratory-confirmed cases in Qatar.MethodsAll SARS-CoV-2 laboratory-confirmed cases with at least one PCR positive swab that is ≥45 days after a first-positive swab were individually investigated for evidence of reinfection, and classified as showing strong, good, some, or weak/no evidence for reinfection. Viral genome sequencing of the paired first-positive and reinfection viral specimens was conducted to confirm reinfection. Risk and incidence rate of reinfection were estimated.ResultsOut of 133,266 laboratory-confirmed SARS-CoV-2 cases, 243 persons (0.18%) had at least one subsequent positive swab ≥45 days after the first-positive swab. Of these, 54 cases (22.2%) had strong or good evidence for reinfection. Median time between first and reinfection swab was 64.5 days (range: 45-129). Twenty-three of the 54 cases (42.6%) were diagnosed at a health facility suggesting presence of symptoms, while 31 (57.4%) were identified incidentally through random testing campaigns/surveys or contact tracing. Only one person was hospitalized at time of reinfection, but still with mild infection. No deaths were recorded. Viral genome sequencing confirmed four out of 12 cases with available genetic evidence. Risk of reinfection was estimated at 0.01% (95% CI: 0.01-0.02%) and incidence rate of reinfection was estimated at 0.36 (95% CI: 0.28-0.47) per 10,000 person-weeks.ConclusionsSARS-CoV-2 reinfection can occur but is a rare phenomenon suggestive of a strong protective immunity against reinfection that lasts for at least a few months post primary infection.

ObjectivesCoronavirus Disease 2019 (COVID-19) is a rapidly expanding global pandemic resulting in significant morbidity and mortality. COVID-19 patients may present with acute myocardial infarction (AMI). The aim of this study is to conduct detailed analysis on patients with AMI and COVID-19.MethodsWe included all patients admitted with AMI and actively known or found to be COVID-19 positive by PCR between the 4th February 2020 and the 11th June 2020 in the State of Qatar. Patients were divided into ST-elevation myocardial infarction (STEMI) and Non-STE (NSTEMI).ResultsThere were 68 patients (67 men and 1 woman) admitted between the 4th of February 2020 and the 11th of June 2020 with AMI and COVID-19. The mean age was 49.1±9 years, 46 patients had STEMI and 22 had NSTEMI. 38% had diabetes mellitus, 31% had hypertension, 16% were smokers, 13% had dyslipidemia, and 14.7% had prior cardiovascular disease. Chest pain and dyspnea were the presenting symptoms in 90% and 12% of patients, respectively. Fever (15%) and cough (15%) were the most common COVID-19 symptoms, while the majority had no viral symptoms. Thirty-nine (33 STEMI and 6 NSTEMI) patients underwent coronary angiography, 38 of them had significant coronary disease. In-hospital MACE was low; 1 patient developed stroke and 2 died.ConclusionContrary to previous small reports, in-hospital adverse events were low in this largest cohort of COVID-19 patients presenting with AMI. We hypothesize patient’s demographics and profile including younger age contributed to these findings. Further studies are required to confirm this observation.Key questionsWhat is already known on this subject?COVID-19 patients may present with acute myocardial infarction (AMI).What might this study add?Contrary to previous small reports, most COVID-19 patients presenting with AMI have significant obstructive coronary artery disease and favorable in-hospital outcome.How might this impact on clinical practice?COVID-19 patients presenting with AMI should be treated according to the standard practice.

BackgroundQatar has a population of 2.8 million, over half of whom are expatriate craft and manual workers (CMW). We aimed to characterize the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic in Qatar.MethodsA series of epidemiologic studies were conducted including analysis of the national SARS-CoV-2 PCR testing and hospitalization database, community surveys assessing current infection, ad-hoc PCR testing campaigns in workplaces and residential areas, serological testing for antibody on blood specimens collected for routine clinical screening/management, national Coronavirus Diseases 2019 (COVID-19) death registry, and a mathematical model.ResultsBy July 10, 397,577 individuals had been PCR tested for SARS-CoV-2, of whom 110,986 were positive, a positivity cumulative rate of 27.9% (95% CI: 27.8-28.1%). PCR positivity of nasopharyngeal swabs in a national community survey (May 6-7) including 1,307 participants was 14.9% (95% CI: 11.5-19.0%); 58.5% of those testing positive were asymptomatic. Across 448 ad-hoc PCR testing campaigns in workplaces and residential areas including 26,715 individuals, pooled mean PCR positivity was 15.6% (95% CI: 13.7-17.7%). SARS-CoV-2 antibody prevalence was 24.0% (95% CI: 23.3-24.6%) in 32,970 residual clinical blood specimens. Antibody prevalence was only 47.3% (95% CI: 46.2-48.5%) in those who had at least one PCR positive result, but it was 91.3% (95% CI: 89.5-92.9%) among those who were PCR positive >3 weeks before serology testing. There were substantial differences in exposure to infection by nationality and sex, reflecting risk differentials between the craft/manual workers and urban populations. As of July 5, case severity rate, based on the WHO severity classification, was 3.4% and case fatality rate was 1.4 per 1,000 persons. Model-estimated daily number of infections and active-infection prevalence peaked at 22,630 and 5.7%, respectively, on May 21 and May 23. Attack rate (ever infection) was estimated at 53.5% on July 12. R0 ranged between 1.45-1.68 throughout the epidemic. Rt was estimated at 0.70 on June 15, which was hence set as onset date for easing of restrictions. Age was by far the strongest predictor of severe, critical, or fatal infection.ConclusionsQatar has experienced a large SARS-CoV-2 epidemic that is rapidly declining, apparently due to exhaustion of susceptibles. The epidemic demonstrated a classic susceptible-infected-recovered “SIR” dynamics with a rather stable R0 of about 1.6. The young demographic structure of the population, in addition to a resourced public health response, yielded a milder disease burden and lower mortality than elsewhere.

Objective To define the epidemiologic curve of COVID-19 in Qatar, determine factors associated with severe or critical illness, and study the temporal relation between public health measures and case finding Design Epidemiologic investigation Setting and Participants All confirmed COVID-19 cases in the State of Qatar between February 28 and April 18, 2020 Main Outcome Measures Number of total and daily new COVID-19 infections; demographic characteristics and comorbidity burden and severity of infection; factors associated with severe or critical illness Results Between February 28 and April 18, 2020 (11:00AM local time), 5,685 cases of COVID-19 were identified. Mean age (SD) was 35.8(12.0) years, 88.9% were male and 8.7% were Qatari nationals. Overall, 83.6% had no concomitant comorbidity, and 3.0% had 3 or more comorbidities. The overwhelming majority (90.9%) were asymptomatic or with minimal symptoms, with 2.0% having severe or critical illness. Presence of hypertension or diabetes were associated with a higher risk of severe or critical illness. Seven deaths were observed during the time interval studied. The epidemiologic curve indicated two distinct patterns of infection, a larger cluster among expatriate craft and manual workers, and a smaller one among Qatari nationals returning from abroad during the epidemic. Conclusion COVID-19 infections in Qatar started in two distinct clusters, but then became more widespread in the population through community transmission. Infections were mostly asymptomatic or with minimal symptoms and associated with very low mortality. Severe/critical illness was associated with presence of hypertension or diabetes. Article Summary Strengths and limitations of this study: National study with unified contact tracing and testing All testing done at a single lab, and all tests performed in the State of Qatar during the study period were included, providing a robust national estimate of the number of infected persons among those tested Comorbidities were retrieved from the electronic medical records using ICD-10 AM codes Exact geographic location and contact tracing data were not included in the current report It is possible that some persons still under care on the study end date may have progressed to more severe disease after that date What is already known on this topic As of May 3, 2020, over 3.4 million persons have been infected with SARS-CoV-2 and over 244,000 deaths have been reported in persons with COVID-19 infection. Those at higher risk of complications include persons over age 60 years and those with chronic comorbid conditions. Mortality rate varies widely among different countries, and this can be associated both to the capacity of the health system to provide effective intensive care including ventilators as well as other factors, including demographic differences. Public health measures seem effective, but there is debate on the extent to which the measures need to be aggressive or the duration for which they should be implemented. What this study adds This study reports on the epidemic curve in a population with a unique demographic structure, comprising an overwhelming majority of expatriates and young male craft and manual workers. This is also the first study that reports on the epidemic curve of an Arab country in the Eastern Mediterranean Region (EMR). The study also overlays major public health measures on the epidemic curve, to provide an understanding of the context in which the epidemic is progressing. Patients with confirmed COVID-19 in Qatar were young with few comorbidities. Case fatality rate was very low (only 7 deaths among 5,685 infected persons). Severe and critical illness were associated with presence of hypertension or diabetes.

Background: Liver abscess carries significant morbidity and mortality rate due to its complications. We aimed to identify laboratory markers associated with septic shock related to pyogenic liver abscess. Methods: The study was conducted at Hamad General Hospital, a tertiary hospital in Qatar. Data were collected retrospectively. All patients diagnosed with pyogenic liver abscess between 2013 and 2017 were included. Liver abscess was diagnosed based on clinical presentation and radiological finding with or without microbiological evidence. Septic shock defined as the need of vasopressors to maintain mean arterial pressure > 60 mmHg. Data has been collected on admission time. Descriptive data were presented in mean ± SD and percentages. Normally distributed data were analyzed by T-test otherwise Mann–Whitney was used.Fisher Exact test was used for categorical data. The level of significance was set at P

Background: Infective endocarditis (IE) is a serious and potentially life-threatening disease. The epidemiology, treatment options, and outcomes have changed considerably over the last two decades. The aim of the study was to describe the epidemiology, clinical characteristics, and outcomes of patients with IE in Qatar. Methods: Patients were identified from Hamad Medical Corporation hospitals’ electronic records, the national referral center for the State of Qatar. We included those aged ≥ 18 years with Duke Criteria-based diagnosis of IE during the period from January 2015 to September 2017. Demographic and clinical data were retrieved. Descriptive statistics were performed, and logistic regression analysis was used to describe the relationship between patient characteristics and all-cause in-hospital mortality. All potentially relevant variables were included in the univariate analysis, while those with p Results: Fifty-seven cases were included, of which 70% were males. The mean age was 51 years ( ± 16.8 years). Eleven (19%) were associated with prosthetic valves, and 6 (11%) with implantable cardiac devices. Fever (84%), dyspnea (46%), and heart failure (37%) were the most common presentations. Only 58% of patients had known preexisting valvular heart disease or an intracardiac device. Skin infections (10 patients, 18%) were the most prevalent portals of infection, followed by venous catheters, recent valve surgery, and implantable cardiac devices. Staphylococci were implicated in 19 (34%) and Streptococcaceae in 9 (16%) patients, whereas 21 (37%) patients were culture negative. Left-side IE (49 patients, 86%) was predominant. Acute kidney injury (AKI) (17 patients, 30%) and heart failure (11 patients, 19%) were common complications. The majority of patients received targeted antimicrobial therapy with at least two active agents. Only 9 (16%) patients underwent surgical intervention. Fourteen (25%) patients died of any cause before hospital discharge. Logistic regression analysis identified septic shock [OR 57.8, 95% CI 2.6–1360.2; p p Conclusion: Staphylococci are the most common microbiological cause of IE in Qatar. Surgical intervention is uncommon, and mortality is relatively high. Our findings suggest that efforts should be directed toward improving IE prevention strategies in high-risk patients, encouraging early microbiological investigations and improving medical and surgical management.

Background Central nervous system (CNS) viral infections are an important cause of morbidity and mortality. No data are available regarding their epidemiology in Qatar. Design We retrospectively evaluated all cerebrospinal fluid findings from January 2011–March 2015 at Hamad Medical Corporation. Those with abnormal CSF finding were included in our study. We excluded those with missing medical records, no clinical evidence of viral CNS infection, or proven bacterial, fungal or tuberculosis CNS infection. CNS clinical findings were classified as meningitis, encephalitis or myelitis. Results Among 7690 patients with available CSF results, 550 cases met the inclusion criteria (meningitis 74.7%; encephalitis 25%; myelitis 0.4%). Two-thirds (65%) were male and 50% were between 16–60 years old. Viral etiology was confirmed in 38% (enterovirus, 44.3%; Epstein-Barr virus, 31%; varicella zoster virus, 12.4%). The estimated incidence was 6.4 per 100,000 population. Two persons died and the rest were discharged to home. Among those with confirmed viral etiology, 83.8% received ceftriaxone (mean duration 7.3 ± 5.2 days), 38% received vancomycin (mean duration 2.7 ± 5.4 days) and 38% received at least one other antibiotic. Intravenous acyclovir was continued for more than 48 h in patients with confirmed negative viral etiology (mean duration 5 ± 5.6 days). Conclusion Viral etiology is not uncommon among those evaluated for CNS infection in Qatar. Clinical outcomes are excellent in this group of patients. Antibiotics and acyclovir are overly used even when a viral etiology is confirmed. There is a need for clinician education regarding etiology and treatment of viral CNS infections.

The effect of prior SARS-CoV-2 infection on vaccine protection remains poorly understood. To assess protection from SARS-CoV-2 breakthrough infection after mRNA vaccination among persons with vs without prior SARS-CoV-2 infection. Matched-cohort studies in Qatar for the BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) vaccines. A total of 1 531 736 individuals vaccinated with either vaccine between December 21, 2020, and September 19, 2021, were followed up beginning 14 days after receiving the second dose until September 19, 2021. Prior SARS-CoV-2 infection and COVID-19 vaccination. Incident SARS-CoV-2 infection, defined as a polymerase chain reaction (PCR)-positive nasopharyngeal swab regardless of reason for PCR testing or presence of symptoms. Cumulative incidence was calculated using the Kaplan-Meier estimator method. The BNT162b2-vaccinated cohort comprised 99 226 individuals with and 290 432 matched individuals without prior PCR-confirmed infection (median age, 37 years; 68% male). The mRNA-1273-vaccinated cohort comprised 58 096 individuals with and 169 514 matched individuals without prior PCR-confirmed infection (median age, 36 years; 73% male). Among BNT162b2-vaccinated persons, 159 reinfections occurred in those with and 2509 in those without prior infection 14 days or more after dose 2. Among mRNA-1273-vaccinated persons, 43 reinfections occurred in those with and 368 infections in those without prior infection. Cumulative infection incidence among BNT162b2-vaccinated individuals was an estimated 0.15% (95% CI, 0.12%-0.18%) in those with and 0.83% (95% CI, 0.79%-0.87%) in those without prior infection at 120 days of follow-up (adjusted hazard ratio for breakthrough infection with prior infection, 0.18 [95% CI, 0.15-0.21]; P

This study explores the association of vaccination against COVID-19 or prior SARS-CoV-2 infection with PCR test positivity in airline passengers arriving in Qatar, February-April 2021.

We assessed whether an influenza vaccination (IV) campaign was effective at increasing vaccination rate in healthcare workers (HCWs) in 2 hospitals in Doha, Qatar that had no mandatory IV policy. The campaign comprised promotional, educational and vaccine delivery interventions; a dedicated IV team; telephone hotline; free IV with improved access, leadership involvement; incentives; group educational sessions; and reporting/tracking activities. During the 2014/15 influenza season, IV rates according to hospital and HCW category were calculated and compared with the 2 seasons before the intervention. The combined mean rate for IV for both hospitals increased for 2014/15 (64.3%) compared with 2013/14 (37.2%) and 2012/13 (28.4%). There was increased IV uptake among doctors and nurses at each hospital, and the IV rate for the 2 hospitals (59.1 and 69.5%) were higher than in 2013/14 (21.1% and 53.2%) and 2012/13 (17.2% and 39.6%). The findings highlight the importance of improving IV rates among HCWs in hospitals with no mandatory vaccination policies through multicomponent interventions.تحسين معدَّلات التطعيم ضد الإنفلونزا بين العاملين في مجال الرعاية الصحية: نهج متعدد الأبعاد في قَطرَ.ملحم مصطفى، عبد اللطيف الخال، منى المسلماني، حسام الصاعوب.أجرينا تقيياً لمدى فعالية إحدى حمات التطعيم ضد الإنفلونزا في زيادة معدَّلات التطعيم بن العاملن في مجال الرعاية الصحية في مستشفيين في الدوحة، قطر، لا تُطبق فيها سياسة إلزامية للتطعيم ضد الإنفلونزا. وتضمنت الحملة إطاق أنشطة ترويجية وتثقيفية وتوفر اللقاحات؛ وإنشاء خط ساخن؛ وتوفر تطعيم مجاني ضد الإنفلونزا مع تحسن الحصول عليه وإشراك القيادات العليا؛ وتقديم حوافز؛ وعقد جلسات تثقيفية جماعية؛ وإجراء أنشطة للإبلاغ/التتبع. وخال موسم الإنفلونزا 2014/2015، احتُسبت معدَّلات التطعيم ضد الإنفلونزا وفقا لفئة المستشفي والعاملن في مجال الرعاية الصحية وجرى مقارنتها بالموسمين السابقين عى التدخل. وازداد المتوسط المجمّع لمعدَّل التطعيم ضد الإنفلونزا لكلتا المستشفيين للفرة 2014/2015 (63.3%) مقارنة بالفرة 2013/2014 (37.2%) والفرة 2012/2013 (28.4%). وازداد معدَّل التطعيم ضد الإنفلونزا بن الأطباء والممرضات في كل مستشفى، وارتفع معدَّل التطعيم ضد الإنفلونزا للمستشفيين (21.1 % و 53.2 %) عن المعدَّل المسجل في الفرة 2012/2013 (17.2% و 39.6%). وتُرز النتائج أهمية تحسن معدَّلات التطعيم ضد الإنفلونزا بن العاملن في مجال الرعاية الصحية في المستشفيات التي لا تطبق سياسات إلزامية للتطعيم عن طريق التدخات المتعددة المكونات.Amélioration des taux de vaccination antigrippale parmi les agents de santé : une approche à plusieurs volets au Qatar.Nous avons cherché à déterminer si la réalisation d’une campagne de vaccination antigrippale influait sur l’augmentation du taux de vaccination chez les agents de santé de deux hôpitaux de Doha (Qatar), qui ne disposaient pas de politiques de vaccination antigrippale obligatoire. La campagne comprenait les éléments suivants : des prestations de promotion et d’éducation, et des interventions concernant les services de vaccination ; des équipes de vaccination antigrippale dédiées ; une ligne téléphonique spéciale ; la vaccination antigrippale gratuite avec un accès amélioré ; l’implication de la direction ; des mesures incitatives ; des sessions de groupe éducatives ; et des activités de notification/ de suivi. Pendant la saison grippale 2014-2015, les taux de vaccination antigrippale pour les hôpitaux et pour chaque catégorie d’agents de santé ont été calculés et comparés avec les deux saisons précédant l’intervention. Le taux moyen combiné pour la vaccination antigrippale pour les deux hôpitaux avait augmenté sur la période 2014-2015 (64,3 %) par rapport aux périodes 2013-2014 (37,2 %) et 2012-2013 (28,4 %). Le recours à la vaccination était en augmentation parmi les médecins et les personnels infirmiers dans chaque hôpital, et le taux de vaccination antigrippale pour les deux hôpitaux (59,1 % et 69,5 %) était plus élevé qu’en 2013-2014 (21,1 % et 53,2 %) et qu’en 2012-2013 (17,2 % et 39,6 %). Les résultats soulignent l’importance d’améliorer, au moyen d’interventions à multiples composantes, les taux de vaccination antigrippale parmi les agents de santé dans les hôpitaux où il n’existe pas de politiques de vaccination obligatoire.

This study aimed to describe the experiences of stress and burnout and sociodemographic factors associated with dimensions of stress among medical residents at Hamad Medical Corporation, Qatar. Medical residents participating in a stress management course were asked to complete an anonymous survey. The survey included demographic questions, the Abbreviated Maslach Inventory, and 4 open-ended questions on experiences with stress. Of the 150 residents participating in the stress management course, 142 responded to the survey, listing an average of 2.2 types of stressors, with workload and workplace relationships as the most frequent. They listed an average of 3.1 coping strategies, most frequently seeking out social support and entertainment. Responses indicated low depersonalization, high personal accomplishment, high satisfaction with medicine and high emotional exhaustion. Training to improve coping and reduce burnout is recommended.الإنهاك ومصادر الإجهاد بين الأطباء المقيمين في مؤسسة حمد الطبية، قطر.عبد الحميد عفانة، جس غنام، إيفيلين هوو، عبد اللطيف الخال، بنان العرب، كارما بيلوند.هدفت هذه الدراسة إلى وصف المعاناة من الإجهاد والإرهاق والعوامل الاجتماعية والسكانية المرتبطة بأبعاد الإجهاد بن الأطباء المقيمن في مؤسسة حمد الطبية، قطر. وقد طُلِب من الأطباء المقيمن المشاركين في دورة لإدارة الإجهاد استكمال استمارة مسح استطلاعي بدون ذكر الأساء. وشمل المسح أسئلة سكانية، والقائمة المخترة "لماساش"، وأربعة أسئلة ذات إجابات مفتوحة تدور حول معاناة الإجهاد. ومن بن الأطباء المقيمن المشاركين في دورة إدارة الإجهاد، وعددهم 150 ، استجاب 142 منهم للمسح، فذكروا قائمة تضم في المتوسط 2.2 نوعاً من مسبِّبات الإجهاد، واعتروا عبء العمل والعلاقات في مكان العمل من المسبِّبات الأكثر شيوعاً. كا وضعوا قائمة تتألف في المتوسط من 3.1 اسراتيجية من اسراتيجيات التكيُّف، لاسيما استماس الدعم الاجتماعي والترفيه. وبينت الإجابات انخفاضاً في التجرُّد، وارتفاعاً في الإنجاز الشخصي والرضا عن مزاولة مهنة الطب ومستوى الإنهاك الانفعالي. ولقد ذكر الأطباء المقيمون في قطر العديد من العوامل المسبِّبة للإجهاد وكذلك مستويات عالية من الإنهاك الانفعالي، وعن اسراتيجيات صحية وغر صحية للتكيُّف. وتوصي الدراسة بالتدريب لتحسن التكيُّف والتخفيف من وطأة الإنهاك.Épuisement professionnel et sources de stress parmi les internes en médecine de la Hamad Medical Corporation, Qatar.La présente étude avait pour objectif de décrire les expériences de stress et d’épuisement professionnel ainsi que les facteurs socio-démographiques associés à l’existence de ce stress parmi les internes en médecine de la Hamad Medical Corporation, au Qatar. Il a été demandé à des internes en médecine participant à un cours de gestion du stress de répondre à une étude anonyme. L’étude incluait des questions d’ordre démographique, la version abrégée de l'inventaire de burnout de Maslach et 4 questions ouvertes sur les expériences de stress. Sur les 150 internes prenant part au cours sur la gestion du stress, 142 ont répondu à l’étude, énumérant une moyenne de 2,2 types de facteurs de stress, à savoir, pour les plus fréquents, la charge de travail et les relations sur le lieu de travail. Ils ont également énuméré une moyenne de 3,1 stratégies d’adaptation, consistant le plus souvent à bénéficier d’un soutien social et à avoir des d’activités divertissantes. Les réponses indiquaient une faible dépersonnalisation, un fort sentiment de réalisation personnelle, un degré de satisfaction élevé concernant le domaine de la médecine et un épuisement émotionnel important. Des formations visant à améliorer l’aptitude des internes à faire face au stress et à l’épuisement professionnel ainsi qu’à réduire ce dernier sont recommandées.

Background The Physician Charter on medical professionalism has been endorsed by professional organizations worldwide, yet it is unclear if this Western framework of professionalism is applicable in non-Western countries. Objective This study examines how physicians practicing in a Middle Eastern context perceive the terms, principles, and commitments outlined in the charter. Methods In May 2013, the authors conducted 6 focus groups with 43 clinician-educators practicing at Hamad Medical Corporation in Doha, Qatar, to discuss the applicability of the Physician Charter in a local context. The research team coded and analyzed transcripts to identify sociocultural influences on professionalism. Results Participants generally expressed agreement with the applicability of the charter's principles to physician professionalism in Qatar. However, 3 contextual factors (religious beliefs and practices, family-centered decision making, and multinationality) complicated the application of the core principles of patient autonomy and social justice. Islamic beliefs reinforced the importance of professional values such as altruism, but presented a barrier to the principle of self-determination for female patients. The family-centered culture in Qatar called for enlarging the scope of patient-centered decision making to include the patient's family. Qatar's multinational population prompted debate over equal treatment and how to conceptualize and implement the principle of social justice. Conclusions Several sociocultural contexts influence the conceptualization of the principles of medical professionalism in Qatar. The findings suggest that contextual factors should be considered when developing or adopting a professionalism framework in an international setting and context.