ABSTRACT
Background: Performance characteristics of SARS-CoV-2 antigen tests among children are limited despite the need for point-of-care testing in school and childcare settings. We describe children seeking SARS-CoV-2 testing at a community site and compare antigen test performance to real-time reverse transcription-polymerase chain reaction (RT-PCR) and viral culture. Methods: Two anterior nasal specimens were self-collected for BinaxNOW antigen and RT-PCR testing, along with demographics, symptoms, and exposure information from individuals [≥]5 years at a community testing site. Viral culture was attempted on residual antigen or RT-PCR positive specimens. Demographic and clinical characteristics, and the performance of SARS-CoV-2 antigen tests, were compared among children (<18 years) and adults. Results: About one in ten included specimens were from children (225/2110); 16.4% (37/225) were RT-PCR positive. Cycle threshold values were similar among RT-PCR positive specimens from children and adults (22.5 vs 21.3, p=0.46) and among specimens from symptomatic and asymptomatic children (22.5 vs 23.2, p=0.39). Sensitivity of antigen test compared to RT-PCR was 73.0% (27/37) among specimens from children and 80.8% (240/297) among specimens from adults; among specimens from children, specificity was 100% (188/188), positive and negative predictive value were 100% (27/27) and 94.9% (188/198) respectively. Virus was isolated from 51.4% (19/37) of RT-PCR positive pediatric specimens; all 19 had positive antigen test results. Conclusions : With lower sensitivity relative to RT-PCR, antigen tests may not diagnose all positive COVID-19 cases; however, antigen testing identified children with live SARS-CoV-2 virus.
Subject(s)
COVID-19ABSTRACT
ABSTRACT BACKGROUND: Information is limited on messenger RNA (mRNA) BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) COVID-19 vaccine effectiveness (VE) in preventing SARS-CoV-2 infection or attenuating disease when administered in real-world conditions. METHODS: Prospective cohorts of 3,975 healthcare personnel, first responders, and other essential and frontline workers completed weekly SARS-CoV-2 testing during December 14 2020--April 10 2021. Self-collected mid-turbinate nasal swabs were tested by qualitative and quantitative reverse-transcription--polymerase-chain-reaction (RT-PCR). VE was calculated as 100%x (1-hazard ratio); adjusted VE was calculated using vaccination propensity weights and adjustments for site, occupation, and local virus circulation . RESULTS: SARS-CoV-2 was detected in 204 (5.1%) participants; 16 were partially ([≥]14 days post-dose-1 to 13 days after dose-2) or fully ([≥]14 days post-dose-2) vaccinated, and 156 were unvaccinated; 32 with indeterminate status (<14 days after dose-1) were excluded. Adjusted mRNA VE of full vaccination was 91% (95% confidence interval [CI]=76%--97%) against symptomatic or asymptomatic SARS-CoV-2 infection; VE of partial vaccination was 81% (95% CI=64%-90%). Among partially or fully vaccinated participants with SARS-CoV-2 infection, mean viral RNA load (Log10 copies/mL) was 40% lower (95% CI=16%-57%), the risk of self-reported febrile COVID-19 was 58% lower (Risk Ratio=0.42, 95% CI=0.18-0.98), and 2.3 fewer days (95% CI=0.8-3.7) were spent sick in bed compared to unvaccinated infected participants. CONCLUSIONS: Authorized mRNA vaccines were highly effective among working-age adults in preventing SARS-CoV-2 infections when administered in real-world conditions and attenuated viral RNA load, febrile symptoms, and illness duration among those with breakthrough infection despite vaccination.