Accuracy of Rapid Antigen vs Reverse Transcriptase–Polymerase Chain Reaction Testing for SARS-CoV-2 Infection in College Athletes During Prevalence of the Omicron Variant

This case series evaluates the performance of rapid antigen tests in detecting SARS-CoV-2 infection in college athletes during prevalence of a dominant Omicron variant.


Introduction
One critical aspect of COVID-19 management has been to isolate or quarantine individuals to prevent viral spread.Reverse transcriptase-polymerase chain reaction (RT-PCR) tests are the criterion standard for diagnosis of SARS-CoV-2 infection but are limited by long turnaround times and complex laboratory methods.
Rapid antigen tests (RATs) can be performed and interpreted in minutes without the use of special equipment.With the rise of each new variant, the accuracy of RATs must be reevaluated.This case series evaluated the performance of RATs in detecting SARS-CoV-2 in the context of a dominant Omicron variant.

Methods
All Stanford University student athletes who reported no history of SARS-CoV-2 infection in the previous 90 days and returned to campus from January 1 through January 11, 2022, self-administered

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Open Access.This is an open access article distributed under the terms of the CC-BY License.In the RT-PCR analysis, the Omicron variant represented 44 of 46 positive cases (95.7%).Four specimens could not be genotyped owing to low viral loads.

Discussion
The overall infectivity rate in our cohort was 10.1%, with 95.7% of infections due to the Omicron variant.The overall sensitivity of RAT was 63.0%, similar to that of 2 recent studies 1,2 that also focused on the Omicron variant.Performance of RAT was better in symptomatic individuals, likely owing to the significant difference in Ct values, because Ct values have been shown to correlate to the sensitivity of RAT in both laboratory 3,4 and clinical studies 1 .Rapid antigen tests were quite specific, with only 1 false-positive finding in the cohort, suggesting that a positive RAT finding in both asymptomatic and symptomatic populations does not require confirmatory RAT or RT-PCR testing.This is consistent with previous studies that have shown excellent specificity. 5,6udy limitations include self-administration and self-reporting of RAT findings, which could confound our results; however, RATs are frequently administered in this fashion.In addition, not every symptomatic patient with a positive RAT finding underwent confirmatory RT-PCR testing, which could cause elevated specificity values.
Rapid antigen testing performed similarly in the detection of the Omicron variant compared with previous variants, with high specificity but poor sensitivity, particularly among asymptomatic individuals.Its use as a screening tool for asymptomatic infection in the setting of widespread prevalence of the Omicron variant may be limited.
Abbott Laboratories) within 24 hours of campus arrival.Symptomatic students with a positive RAT result were isolated without confirmatory RT-PCR testing; asymptomatic students with a positive RAT result underwent RT-PCR testing (eMethods in the Supplement).Statistical analysis was performed using Prism, version 9.0 (GraphPad Software), for data visualization and Mann-Whitney U tests for median cycle threshold (Ct) value comparison, with 2-sided P < .05indicating statistical significance.This study was approved with a waiver of informed consent by the Stanford University Institutional Review Board.The reporting guideline for case series was used for this study.