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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) initially infects and replicates in epithelial cells of the nasopharynx where there are relatively high levels of angiotensin-converting enzyme 2 receptor, which correlates with the highest sensitivity time point of the nasopharyngeal swab (NPS) real-time polymerase chain reaction (RT-PCR) during the first week, with subsequent decline thereafter. As viral shedding progresses throughout the respiratory tract, the virus can be detectable for up to 30 days in bronchoalveolar fluids. This report presents three cases of acute respiratory distress in the setting of multifocal pneumonia, with multiple false-negative NPS SARS-CoV-2/RT-PCR but positive SARS-CoV-2/RT-PCR in bronchoalveolar lavage (BAL) samples. Molecular RT-PCR testing remains the gold standard in the diagnosis of SARS-CoV-2 infection. However, the diagnostic accuracy of NPS RT-PCR may be affected by several factors. SARS-CoV-2/RT-PCR in BAL samples increases the diagnostic yield for coronavirus disease 2019 pneumonia; however, it is not widely available in many institutions and can be clinically challenging to perform. A multimodal approach is required for prompt diagnosis, especially in patients with a progressive disease, where a delay in therapy can be clinically detrimental., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Poli De Frias et al.)

Background: Effective and precise SARS-CoV-2 detection assays are crucial for maintaining regular hospital routines and identifying infected hospital employees and infected patients before hospital admission. Inconclusive PCR test results of potentially infectious borderline SARS-CoV-2 patients can confuse clinicians and delay appropriate infection control., Objectives and Study Design: In this retrospective study, we followed up borderline SARS-CoV-2 patients who were tested (from the second sample with the same method) at the Clinical Department of Clinical Microbiology. We aimed to determine the positivity conversion ratio within 7 days after inconclusive PCR test results., Results: Out of 247 borderline patients, who were resampled and retested in the same laboratory, 60 patients (29.4%) showed conversion of the borderline viral load (inconclusive RT-PCR test) to a positive RT-PCR test result., Conclusions: Our results highlight the need for retesting of borderline patients with inconclusive SARS-CoV-2 results. Follow-up testing of inconclusive PCR results within 7 days can identify additional positive results and reduce the potential risk of intrahospital transmission.

Introduction: Persistent symptoms have recently emerged as a clinical issue in COVID-19. We aimed to assess the prevalence and risk factors in symptomatic non-hospitalized individuals with mild COVID-19., Methods: We performed a prospective cohort study of symptomatic COVID-19 outpatients, from March to May 2020, with weekly phone calls from clinical onset until day 30 and up to day 60 in case of persistent symptoms. The main outcomes were the proportion of patients with complete recovery at day 30 and day 60 and factors associated with persistent symptoms., Results: We enrolled 429 individuals mostly women (72.5%) and healthcare workers (72.5%), with a median age of 41.6 years [IQR 30-51.5]. Symptoms included: cough (69.7%), asthenia (68.8%), anosmia (64.8%), headaches (64.6%), myalgia (62.7%), gastrointestinal symptoms (61.8%), fever (61.5%), and ageusia (60.8%). Mean duration of disease was 27 days (95%CI: 25-29). The rate of persistent symptoms was 46.8% at day 30 and 6.5% at day 60 consisting in asthenia (32.6%), anosmia (32.6%), and ageusia (30.4%). The probability of complete recovery was 56.3% (95%CI: 51.7-61.1) at day 30 and 85.6% (95%CI: 81.2-89.4) at day 60. Factors associated with persistent symptoms were age>40 (HR 0.61), female sex (HR 0.70), low cycle threshold (HR 0.78), and ageusia (HR 0.59)., Conclusions: COVID-19 - even in its mild presentation - led to persistent symptoms (up to one month) in nearly half of individuals. Identification of risk factors such as age, gender, ageusia and viral load is crucial for clinical management and argues for the development of antiviral agents., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

A detailed history and diagnostic evaluation for recent or past COVID-19 infection is vital in patients presenting with Sudden Sensorineural Hearing Loss (SSNHL) since SSNHL could be a sequelae of COVID-19 and timely diagnosis and intervention could significantly improve hearing and quality of life., Competing Interests: None declared., (© 2021 The Authors. Clinical Case Reports published by John Wiley & Sons Ltd.)

Background: This study aimed to evaluate the impact of four different reverse transcription quantitative PCR (RT-qPCR) master mixes on the performance of SARS-CoV-2 diagnostic PCRs using three primer/probe assays targeting the N gene (A, B and C). The dynamic range and lowest detected quantity was determined using a SARS-CoV-2 partial N gene RNA transcript dilution series (100,000-1 copy/μl) and verified using 72 nose and throat swabs, 29 of which tested positive for SARS-CoV-2 RNA., Results: Assay C consistently detected the lowest quantity of partial N gene RNA transcript with all mastermixes. The Takara One Step PrimeScript™ III RT-PCR Kit mastermix enabled all primer pairs to detect the entire dynamic range evaluated, with the Qiagen Quantifast and Thermofisher TaqPath 1-Step kits also performing well. Sequences from all three primer/probe sets tested in this study (assay A, B and C) have 100 % homology to ≥97 % of the of SARS-CoV-2 sequences available up to 31st December 2020 (n = 291,483 sequences)., Conclusions: This work demonstrates that specific assays (in this case assay C) can perform well in terms of dynamic range and lowest detected quantity regardless of the mastermix used. However we also show that, by choosing the most appropriate mastermix, poorer performing primer pairs are also able to detect all of the template dilutions investigated. This work increases the potential options when choosing assays for SARS-CoV-2 diagnosis and provides solutions to enable them to work with optimal analytical sensitivity., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The world at large cannot afford to miss even a single case of COVID-19 because of its far-reaching consequences; therefore, the diagnostic development to achieve test with much higher sensitivity should be made available at a mass level as early as possible., How to Cite This Article: Garg SK. Differing Sensitivity of COVID-19 PCR Tests and Consequences of the False-negative Report: A Small Observation. Indian J Crit Care Med 2021;25(9):1077-1078., Competing Interests: Source of support: Nil Conflict of interest: None, (Copyright © 2021; Jaypee Brothers Medical Publishers (P) Ltd.)

Introduction: Few data on the diagnostic performance of serological tests for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are currently available. We evaluated sensitivity and specificity of five different widely used commercial serological assays for the detection of SARS-CoV-2-specific IgG, IgM, and IgA antibodies using reverse transcriptase-PCR assay in nasopharyngeal swab as reference standard test. Methods: A total of 337 plasma samples collected in the period April-June 2020 from SARS-CoV-2 RT-PCR positive ( n = 207) and negative ( n = 130) subjects were investigated by one point-of-care lateral flow immunochromatographic assay (LFIA IgG and IgM, Technogenetics) and four fully automated assays: two chemiluminescence immunoassays (CLIA-iFlash IgG and IgM, Shenzhen YHLO Biotech and CLIA-LIAISON ® XL IgG, DiaSorin), one electrochemiluminescence immunoassay (ECLIA-Elecsys ® total predominant IgG, Roche), and one enzyme-linked immunosorbent assay (ELISA IgA, Euroimmune). Results: The overall sensitivity of all IgG serological assays was >80% and the specificity was >97%. The sensitivity of IgG assays was lower within 2 weeks from the onset of symptoms ranging from 70.8 to 80%. The LFIA and CLIA-iFlash IgM showed an overall low sensitivity of 47.6 and 54.6%, while the specificity was 98.5 and 96.2%, respectively. The ELISA IgA yielded a sensitivity of 84.3% and specificity of 81.7%. However, the ELISA IgA result was indeterminate in 11.7% of cases. Conclusions: IgG serological assays seem to be a reliable tool for the retrospective diagnosis of SARS-CoV-2 infection. IgM assays seem to have a low sensitivity and IgA assay is limited by a substantial rate of indeterminate results., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Chiereghin, Zagari, Galli, Moroni, Gabrielli, Venturoli, Bon, Rossini, Saracino, Pavoni, Lafratta, Deni, Felici, Borghi, Guerra, Raumer, Lodi, Viale, Attard, Lazzarotto and IRCCS St. Orsola Polyclinic of Bologna COVID-19 Research Team.)

Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Healthcare workers (HCWs) are at increased risk of infection by the virulent severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Though data exist on the positivity rate of the SARS-CoV-2 reverse transcription polymerase chain reaction (RT-PCR) test as well as COVID-19-related deaths amongst HCWs in South Africa, the overall infection rate remains underestimated by these indicators. It is also unclear whether the humoral immune response after SARS-CoV-2 infection offers durable protection against reinfection. This study will assess the SARS-CoV-2 seroprevalence amongst HCWs in the Eastern Cape (EC) and examine the longitudinal changes (rate of decay) in the antibody levels after infection in this cohort. Using a multi-stage cluster sampling of healthcare workers in selected health facilities in the EC, a cross-sectional study of 2250 participants will be recruited. In order to assess the community infection rate, 750 antenatal women in the same settings will be recruited. Relevant demographic and clinical characteristics will be obtained by a self-administered questionnaire. A chemiluminescent microparticle immunoassay (CMIA) will be used for the qualitative detection of IgG antibodies against SARS-CoV-2 nucleocapsid protein. A nested cohort study will be conducted by performing eight-weekly antibody assays (X2) from 201 participants who tested positive for both SARS-CoV-2 RT-PCR and serology. Logistic regression models will be fitted to identify the independent risk factors for SARS-CoV-2 infection. The cumulative SARS-CoV-2 infection rate and infection fatality rate among the frontline HCWs will be estimated. In addition, the study will highlight the overall effectiveness of infection prevention and control measures (IPC) per exposure sites/wards at the selected health facilities. Findings will inform the South African Department of Health's policies on how to protect HCWs better as the country prepares for the second wave of the SARS-CoV pandemic.

The clinical false negative rate of reverse transcriptase polymerase chain reaction (RT-PCR) testing for SARS-CoV-2 on a single upper respiratory tract sample was calculated using convalescent antibody testing as a comparator. The sensitivity in symptomatic individuals was 86.2% (25/29). Of the missed cases, one (3.5%) was detected by repeat RT-PCR, one by CT thorax and two (7.1%) by convalescent antibody. The clinical false negative rate of a single RT-PCR on an upper respiratory tract sample of 14% in symptomatic patients is reassuring when compared to early reports. This report supports a strategy of combining repeat swabbing, use of acute and convalescent antibody testing and CT thorax for COVID-19 diagnosis., (© 2020 Royal College of Physicians 2020. All rights reserved.)

Objective: To determine the diagnostic yield of repeat testing for SARS-CoV-2., Methods: A retrospective analysis was performed of all SARS-CoV-2 test results within the UCLA Health System between March 9th and April 29th, 2020. All patients with repeat test results were identified and those with discordant results were reviewed., Results: Between March 9th and April 29th there were 10,165 SARS-CoV-2 test results, of which 630 (6.2%) were positive. Among the 904 patients with repeat test results, 808 (89.4%) were initially negative and 96 (10.6%) were initially positive. Among the 808 patients with an initial negative test, 15 (1.9%) subsequently tested positive. Eleven cases with an initial negative SARS-CoV-2 test and without a known prior positive SARS-CoV-2 test were reviewed; 6 were employed as healthcare workers and 10 were positive on the second test., Conclusions: We found a low diagnostic yield of repeat testing for SARS-CoV-2 in our health system. Repeat testing might prove useful in certain clinical scenarios, such as in healthcare workers, when symptoms develop after a negative test, and in hospitalized patients with a high clinical suspicion for COVID-19., (Copyright © 2020 The Author(s). Published by Elsevier Ltd.. All rights reserved.)