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We read with great interest the article published by Zuo et al , which highlighted the presence of SARS-CoV-2 RNA in stool samples during active and convalescence phases of COVID-19 infection.1 However, no study has reported the presence of viral antigens within GI and hepatic organs during the convalescent phase. Using conventional immunohistochemistry, we detected SARS-CoV-2 nucleocapsid protein (NP) in the colon, appendix, ileum, haemorrhoid, liver, gallbladder and lymph nodes (figure 1A–K) from five patients who recovered from COVID-19, ranging from 9 to 180 days after testing negative for SARS-CoV-2 (online supplemental table 1). Notably, when multiple tissues were obtained from one patient (patients 1 and 4), all the tissues showed the presence of the viral antigen, suggesting widespread multiorgan involvement of the viral infection. Interestingly, for the colon, the viral antigen was only present in normal colonic crypts and polyps but not in the neoplastic tissues (figure 1Q). Similar negative staining in the hepatocellular carcinoma tumour region was also observed (figure 1R) albeit the positive staining in some of the scattered immune cells (figure 1D). Validating our findings, we detected SARS-CoV-2 spike protein (figure 1L–P) and RNA (figure 2B–F) in the above-mentioned tissues using conventional immunohistochemistry and RNAscope, respectively. However, we were unable to detect viral RNA in some patients’ tissues (online supplemental table 1), possibly because of higher RNA degradation rate as compared with protein and other patient-dependent factors such as disease severity, time since recovery and basal metabolic rate.### Supplementary data [gutjnl-2021-324280supp001.pdf] Figure 1 Immunohistochemical staining of the SARS-CoV-2 nucleocapsid and spike proteins in intestinal and hepatic tissues. (A and B) Positive SARS-CoV-2 nucleocapsid protein (NP) staining in colonic crypts (A) and appendix (B), both with a granular supranuclear cytoplasmic pattern. (C) positive SARS-CoV-2 NP staining in scattered immune cells …

Background: We studied humoral and cellular responses against SARS-CoV-2 longitudinally in a homogeneous population of healthy young/middle-aged men of South Asian ethnicity with mild COVID-19. Met...

During the COVID-19 pandemic, distinguishing dengue from cases of COVID-19 in endemic areas can be difficult. In a tertiary hospital contending with COVID-19 during a dengue epidemic, a triage strategy of routine COVID-19 testing for febrile patients with viral prodromes was used. All febrile patients with viral prodromes and no epidemiologic risk for COVID-19 were first admitted to a designated ward for COVID-19 testing, where enhanced personal protective equipment was used by healthcare workers until COVID-19 was ruled out. From January to May 2020, 11,086 admissions were screened for COVID-19; 868 cases of COVID-19 were diagnosed in our institution, along with 380 cases of dengue. Only 8.5% (943/11,086) of suspected COVID-19 cases were concurrently tested for dengue serology due to a compatible overlapping clinical syndrome, and dengue was established as an alternative diagnosis in 2% (207/10,218) of suspected COVID-19 cases that tested negative. There were eight COVID-19 cases with likely false-positive dengue serology and one probable COVID-19/dengue coinfection. From April to May 2020, 251 admissions presenting as viral prodromes with no respiratory symptoms were screened; of those, 15 cases had COVID-19, and 2/15 had false-positive dengue IgM. Epidemiology investigations showed no healthcare-associated transmission. In a dengue epidemic season coinciding with a COVID-19 pandemic, dengue was established as an alternative diagnosis in a minority of COVID-19 suspects, likely due to early availability of basic diagnostics. Routine screening of patients with viral prodromes during a dual outbreak of COVID-19 and dengue enabled containment of COVID-19 cases masquerading as dengue with false-positive IgM.

To curb the spread of the COVID‐19 virus, the use of face masks such as disposable surgical masks and N95 respirators is being encouraged and even enforced in some countries. The widespread use of masks has resulted in global shortages and individuals are reusing them. This calls for proper disinfection of the masks while retaining their protective capability. In this study, the killing efficiency of ultraviolet‐C (UV‐C) irradiation, dry heat, and steam sterilization against bacteria (Staphylococcus aureus), fungi (Candida albicans), and nonpathogenic virus (Salmonella virus P22) is investigated. UV‐C irradiation for 10 min in a commercial UV sterilizer effectively disinfects surgical masks. N95 respirators require dry heat at 100 °C for hours while steam treatment works within 5 min. To address the question on safe reuse of the disinfected masks, their bacteria filtration efficiency, particle filtration efficiency, breathability, and fluid resistance are assessed. These performance factors are unaffected after 5 cycles of steam (10 min per cycle) and 10 cycles of dry heat at 100 °C (40 min per cycle) for N95 respirators, and 10 cycles of UV‐C irradiation for surgical masks (10 min per side per cycle). These findings provide insights into formulating the standard procedures for reusing masks without compromising their protective ability., The ongoing coronavirus pandemic has resulted in global shortages of disposable face masks, prompting them to be reused. To ensure safe reuse, masks undergo various disinfection methods including ultraviolet‐C irradiation, dry heat, and steam sterilization. Particularly, five cycles of steam treatment (10 min per cycle) do not impair the filtration capabilities, breathability, and fluid resistance property of N95 respirators.

ImportanceCOVID-19 pandemic control measures affect the prevalence of other respiratory viruses. Effects on some viruses have been described; however, the broader impact and temporal relationship of control measures on virus decline and subsequent re-emergence have not been thoroughly documented. Understanding these phenomena may influence health policies.ObjectiveTo examine the prevalence of unrelated respiratory viruses in relation to population-wide pandemic response measures and phases in 2020 in Singapore.Design, Setting, and ParticipantsData from respiratory multiplex PCRs from 3 major hospitals (total 3700 beds) in Singapore were collated. The full dataset consisted of 42,558 test results, 19,898 from 2019 and 22,660 from 2020.Main Outcomes and MeasuresWeekly virus prevalence data were mapped onto prevailing pandemic response measures, in order to elucidate temporal relationships and differential virus responses. Pre-pandemic data from 2019 were compared with data from 2020.ResultsEarly response measures, even before national lockdown, were followed by a dramatic reduction of influenza viruses and a more gradual decline of other respiratory viruses, including respiratory syncytial virus, parainfluenza viruses, endemic coronaviruses and metapneumovirus. Marked decline of enterovirus/rhinovirus and adenovirus, however, was only observed during lockdown. About 13 weeks into phased reopening, enterovirus/rhinovirus re-emerged, followed by adenovirus, the latter mainly in the pediatric population. All other viruses remained at low levels until the end of 2020.Conclusions and RelevanceCOVID-19 control measures in Singapore had a significant impact on a broad range of respiratory viruses. Effects of various control measures varied between phases and different viruses. Influenza viruses declined earliest and most dramatically; relaxation of measures was followed by re-emergence of enterovirus/rhinovirus and adenovirus. These patterns are presumably a result of different propensities for contact versus droplet and overall ease of transmission, and different virus reservoirs. Further studies into these phenomena are a matter of public health importance.Key PointsQuestionWhat were the effects of COVID-19 pandemic control measures in Singapore on the prevalence of other respiratory viruses?FindingsViruses responded differently to control measures. Influenza viruses declined rapidly after early control measures and remained near-absent during reopening after lockdown. Enterovirus/rhinovirus and adenovirus declined later and re-emerged earlier than other viruses during phased reopening.MeaningPopulation-wide interventions resulted in a broad decline and subsequent differential re-emergence of non-targeted respiratory viruses, corresponding to different patterns of virus response to control measures.

The COVID-19 pandemic brought unprecedented challenges to the world. Many jurisdictions implemented control measures, such as border closures, lockdowns, school and business closures, travel restrictions, mask wearing, and social distancing. This was associated with changes in the prevalence of other respiratory viruses, predominantly influenza viruses1,2 but others as well.3 Singapore represents a unique setting that is credited with having a successful COVID-19 response. It went through different response phases, from prelockdown (pandemic level 3) to a full lockdown (known as circuit breaker), followed by a phased reopening, during which schools and businesses reopened but social distancing measures and universal mask wearing remained in place (eTable in the Supplement). Our aim in this study was to assess the associated changes in respiratory virus prevalence in 2020 compared with the prepandemic year 2019. Published version

Background: We studied humoral and cellular responses against SARS-CoV-2 longitudinally in a homogeneous population of healthy young/middle-aged men of South Asian ethnicity with mild COVID-19. Methods: In total, we recruited 994 men (median age: 34 years) post-COVID-19 diagnosis. Repeated cross-sectional surveys were conducted between May 2020 and January 2021 at six time points – day 28 (n = 327), day 80 (n = 202), day 105 (n = 294), day 140 (n = 172), day 180 (n = 758), and day 280 (n = 311). Three commercial assays were used to detect anti-nucleoprotein (NP) and neutralizing antibodies. T cell response specific for Spike, Membrane and NP SARS-CoV-2 proteins was tested in 85 patients at day 105, 180, and 280. Results: All serological tests displayed different kinetics of progressive antibody reduction while the frequency of T cells specific for different structural SARS-CoV-2 proteins was stable over time. Both showed a marked heterogeneity of magnitude among the studied cohort. Comparatively, cellular responses lasted longer than humoral responses and were still detectable nine months after infection in the individuals who lost antibody detection. Correlation between T cell frequencies and all antibodies was lost over time. Conclusion: Humoral and cellular immunity against SARS-CoV-2 is induced with differing kinetics of persistence in those with mild disease. The magnitude of T cells and antibodies is highly heterogeneous in a homogeneous study population. These observations have implications for COVID-19 surveillance, vaccination strategies, and post-pandemic planning.

By using a rapid whole-blood T cell activation assay measuring cytokines released by SARS-CoV-2–specific T cells, Le Bert et al. show that individuals who clear SARS-CoV-2 infection without symptoms mount a highly functional virus-specific cellular immune response., The efficacy of virus-specific T cells in clearing pathogens involves a fine balance between antiviral and inflammatory features. SARS-CoV-2–specific T cells in individuals who clear SARS-CoV-2 without symptoms could reveal nonpathological yet protective characteristics. We longitudinally studied SARS-CoV-2–specific T cells in a cohort of asymptomatic (n = 85) and symptomatic (n = 75) COVID-19 patients after seroconversion. We quantified T cells reactive to structural proteins (M, NP, and Spike) using ELISpot and cytokine secretion in whole blood. Frequencies of SARS-CoV-2–specific T cells were similar between asymptomatic and symptomatic individuals, but the former showed an increased IFN-γ and IL-2 production. This was associated with a proportional secretion of IL-10 and proinflammatory cytokines (IL-6, TNF-α, and IL-1β) only in asymptomatic infection, while a disproportionate secretion of inflammatory cytokines was triggered by SARS-CoV-2–specific T cell activation in symptomatic individuals. Thus, asymptomatic SARS-CoV-2–infected individuals are not characterized by weak antiviral immunity; on the contrary, they mount a highly functional virus-specific cellular immune response., Graphical Abstract

The efficacy of virus-specific T cells in clearing pathogens involves a fine balance between their antiviral and inflammatory features. SARS-CoV-2-specific T cells in individuals who clear SARS-CoV-2 infection without symptoms or disease could reveal non-pathological yet protective characteristics. We therefore compared the quantity and function of SARS-CoV-2-specific T cells in a cohort of asymptomatic individuals (n=85) with that of symptomatic COVID-19 patients (n=76), at different time points after antibody seroconversion. We quantified T cells reactive to structural proteins (M, NP and Spike) using ELISpot assays, and measured the magnitude of cytokine secretion (IL-2, IFN-γ, IL-4, IL-6, IL-1β, TNF-α and IL-10) in whole blood following T cell activation with SARS-CoV-2 peptide pools as a functional readout. Frequencies of T cells specific for the different SARS-CoV-2 proteins in the early phases of recovery were similar between asymptomatic and symptomatic individuals. However, we detected an increased IFN-γ and IL-2 production in asymptomatic compared to symptomatic individuals after activation of SARS-CoV-2-specific T cells in blood. This was associated with a proportional secretion of IL-10 and pro-inflammatory cytokines (IL-6, TNF-α and IL-1β) only in asymptomatic infection, while a disproportionate secretion of inflammatory cytokines was triggered by SARS-CoV-2-specific T cell activation in symptomatic individuals. Thus, asymptomatic SARS-CoV-2 infected individuals are not characterized by a weak antiviral immunity; on the contrary, they mount a robust and highly functional virus-specific cellular immune response. Their ability to induce a proportionate production of IL-10 might help to reduce inflammatory events during viral clearance.

BackgroundThe SARS-CoV-2 shares 74.5% genome identity with SARS-CoV, both exhibiting a similar well conserved structure. Therefore, antibodies produced in COVID-19 and SARS patients should not be that dissimilar. We evaluated SARS-CoV test assays to detect for the presence of antibodies to SARS-CoV-2 and tried to determine the timing of appearance of these antibodies by testing serial sera from these patients.MethodsTests were carried out using ELISA (total antibodies) and indirect immunofluorescence (IIFA) (IgM & IgG) methods on serial sera from patients confirmed with SARS-CoV-2 infection.ResultsCross-reactivity was seen in these two test assays with sera from COVID-19 patients and was detected in 6 out of 7 patients from 7 days after onset of symptoms. Five of the patients had detectable antibodies by the 3rd week into their illness and there was evidence of seroconversion in 4 patients. The IIFA method was marginally more sensitive compared to the ELISA assay, however the IIFA IgM test was not useful in the early phase of the illness with poor sensitivity.ConclusionsExisting diagnostic assays for SARS-CoV can detect antibodies in patients who were diagnosed with COVID-19. These assays maybe be utilized as an interim measure in epidemiological investigations for contact tracing and to determine the extent of community spread of this new emerging virus pending the availability of specific serology tests for SARS-CoV-2.

Psoas abscess is commonly regarded as an unusual cause for back pains and usually associated with significant risk factors or co-morbidities. We describe the clinical presentation and findings of a young male Caucasian with bilateral psoas abscesses caused by an unusual organism, Janibacter terrae (an environmental organism) not previously described in literature and the challenges faced in managing this infection. There are very few case reports of this organism causing opportunistic infections, all reported bacteraemia mainly in patients with significant co-morbidities. This case highlights the importance of psoas abscess as a differential diagnosis in patients presenting with back pain and the potential for this organism to cause abscesses in healthy individuals which was difficult to identify using conventional laboratory methods. Management of this infection was challenging and there is limited experience with antimicrobial treatment for this organism.