ABSTRACT
Rapid Antigen Tests (RAT) have become an invaluable tool for combating the COVID-19 pandemic. However, concerns have been raised regarding the ability of existing RATs to effectively detect emerging SARS-CoV-2 variants. We compared the performance of eight commercially available, emergency use authorized RATs against the Delta and Omicron SARS-CoV-2 variants using individual patient and serially diluted pooled clinical samples. The RATs exhibited lower sensitivity for Omicron samples when using PCR Cycle threshold (CT) value (a proxy for RNA concentration) as the comparator. Interestingly, however, they exhibited similar sensitivity for Omicron and Delta samples when using quantitative antigen concentration as the comparator. We further found that the Omicron samples had lower ratios of antigen to RNA, which offers a potential explanation for the apparent lower sensitivity of RATs for that variant when using CT value as a reference. Our findings underscore the complexity in assessing RAT performance against emerging variants and highlight the need for ongoing evaluation in the face of changing population immunity and virus evolution.
Subject(s)
COVID-19ABSTRACT
Background. The goal of this study was to characterize the ability of school-aged children to self-collect adequate anterior nares (AN) swabs for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing. Methods. From July to August 2021, 287 children, age 4-14 years-old, were prospectively enrolled in the Atlanta area. Symptomatic (n=197) and asymptomatic (n=90) children watched a short instructional video before providing a self-collected AN specimen. Health care workers (HCWs) then collected a second specimen, and useability was assessed by the child and HCW. Swabs were tested side-by-side for SARS-CoV-2. RNase P RNA detection was investigated as a measure of specimen adequacy. Results. Among symptomatic children, 87/196 (44.4%) tested positive for SARS-CoV-2 by both self- and HCW-swab. Two children each were positive by self- or HCW-swab; one child had an invalid HCW-swab. Compared to HCW-swabs, self-collected swabs had 97.8% and 98.1% positive and negative percent agreements, respectively, and SARS-CoV-2 Ct values did not differ significantly between groups. Participants [≤]8 years-old were less likely than those >8 to be rated as correctly completing self-collection, but SARS-CoV-2 detection did not differ. Based on RNase P RNA detection, 270/287 children (94.1%) provided adequate self-swabs versus 277/287 (96.5%) HCW-swabs (p=0.24) with no difference when stratified by age. Conclusions. Children, aged 4-14 years-old, can provide adequate AN specimens for SARS-CoV-2 detection when presented with age-appropriate instructional material, consisting of a video and a handout, at a single timepoint. These data support the use of self-collected AN swabs among school-age children for SARS-CoV-2 testing.