Testing out of quarantine

D'Agostino McGowan, L.; Lee, E. C.; Grantz, K. H.; Kucirka, L.; Gurley, E. S.; Lessler, J.

Since SARS-CoV-2 emerged, a 14-day quarantine has been recommended based on COVID-19's incubation period. Using an RT-PCR or rapid antigen test to "test out" of quarantine is a frequently proposed strategy to shorten duration without increasing risk. We calculated the probability that infected individuals test negative for SARS-CoV-2 on a particular day post-infection and remain symptom free for some period of time. We estimate that an infected individual has a 20.1% chance (95% CI 9.8-32.6) of testing RT-PCR negative on day five post-infection and remaining asymptomatic until day seven. We also show that the added information a test provides decreases as we move further from the test date, hence a less sensitive test that returns rapid results is often preferable to a more sensitive test with a delay.