Daily Rapid Antigen Exit Testing to Tailor University COVID-19 Isolation Policy

Abstract

We evaluated daily rapid antigen test (RAT) data from 323 COVID-19–positive university students in Connecticut, USA, during an Omicron-dominant period. Day 5 positivity was 47% for twice-weekly screeners and 26%–28% for less-frequent screeners, approximately halving each subsequent day. Testing negative >10 days before diagnosis (event time ratio (ETR) 0.85 [95% CI 0.75–0.96]) and prior infection >90 days (ETR 0.50 [95% CI 0.33–0.76]) were significantly associated with shorter RAT positivity duration. Symptoms before or at diagnosis (ETR 1.13 [95% CI 1.02–1.25]) and receipt of 3 vaccine doses (ETR 1.20 [95% CI 1.04–1.39]) were significantly associated with prolonged positivity. Exit RATs enabled 53%–74% of students to leave isolation early when they began isolation at the time of the first positive test, but 15%–22% remained positive beyond the recommended isolation period. Factors associated with RAT positivity duration should be further explored to determine relationships with infection duration.