Evaluation of “test to return” after COVID-19 diagnosis in a Massachusetts public school district

Abstract

The Centers for Disease Control allows rapid antigen testing (RAT) towards the end of a 5-day isolation for COVID-19 infection to determine eligibility to leave isolation. The impact of a test-to-return (TTR) program in schools is unknown. In January 2022 a Massachusetts school district initiated a TTR program utilizing a single school-administered RAT on days 5-9 after symptom onset or positive test, whichever was first. Of 636 students with COVID-19 infection, 408 (64.2%) participated in TTR; of these, 128 (31.4%) had a positive TTR rapid antigen test. Students who were symptomatic at any time during their infection were more likely to have a positive TTR than those who were never symptomatic (43.1% vs. 17.3%); positivity rates were lower when TTR was performed later during days 6-9. TTR may identify students who carry higher viral loads after recovery from COVID-19 infection thereby extending their isolation, while facilitating earlier return of those with negative results.

Daily Rapid Antigen Testing in a University Setting to Inform COVID-19 Isolation Duration Policy

“…Studies of managed isolation programs reported RAT positivity ranging from 31-58% on days 5-9 of isolation and PCR positivity ranging from 39-52% on day 5, 25-33% on day 6, and 13-22% on day 7. 3,[5][6][7] Our results indicate that a 7-day isolation period is required to achieve at least a 90% probability of being negative without exit testing (Figure 1A-C). 5-day and 6-day isolation periods are associated, respectively, with a 53-74% and 78-85% probability of testing negative (range across last negative test categories).…”

“…Studies of managed isolation programs reported RAT positivity ranging from 31-58% on days 5-9 of isolation and PCR positivity ranging from 39-52% on day 5, 25-33% on day 6, and 13-22% on day 7. 3,5–7…”

“…Studies of managed isolation programs through schools or employers found positivity via rapid antigen test (RAT) on days 5-9 ranging from 31-58%, although daily testing among all persons was not conducted. [5][6][7] A near-daily PCR testing study reported a day 5 positivity of ranging from 39-52%. 3 However, key gaps in our understanding persist.…”

Viral dynamics of Omicron and Delta SARS-CoV-2 variants with implications for timing of release from isolation: a longitudinal cohort study

“…19 Our findings are similar to early reports in other settings suggesting 30-55% positive antigen RDT between days 5-10 of illness. 20,21,7 One study, using a different antigen test, showed higher antigen RDT positivity (75%), but similar culture positivity (35%) at day 6. 20 Given the similar negative predictive value, the work by Cosimi et al 22 highlights possible differing performance characteristics at the end of infection across tests.…”

“…2 A test to return program in a Massachusetts school district found positivity rate of 35% when performed day 6 from symptom onset or positive test, concluding that such a program helps identify those safest to return to the classroom prior to 10 days. 7 Modeling efforts have further suggested that antigen RDT could be used to both reduce the self-solation period while preventing ongoing disease transmission. 8 New SARS-CoV-2 variants have shown increased transmissibility, potentially impacting best practices for isolation guidelines.…”