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

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.

Automated summary

We evaluated daily rapid antigen test data from COVID-19-positive university students in Connecticut, USA, during the Omicron-dominant period. The study found that the positivity rate decreased by approximately half each subsequent day for less-frequent screeners. Testing negative more than 10 days before diagnosis and prior infection more than 90 days were associated with shorter RAT positivity duration, while symptoms before or at diagnosis and receipt of 3 vaccine doses were associated with prolonged positivity. Exit RATs allowed a significant number of students to leave isolation early, although a percentage remained positive beyond the recommended isolation period.