key: cord-0769190-iiibgeve authors: Nelson, S. B.; Brenner, I. R.; Homan, E.; Lee, S. B.; Bongiorno, C.; Pollock, N.; Ciaranello, A. L. title: Evaluation of test-to-return after COVID-19 diagnosis in a Massachusetts public school district date: 2022-02-15 journal: nan DOI: 10.1101/2022.02.11.22270843 sha: 4348aae33a18733e6d20b4e8c52bbae41376b4ee doc_id: 769190 cord_uid: iiibgeve 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. In December 2021, the US Centers for Disease Control and Prevention (CDC) updated guidance for people with SARS-CoV-2 infection, enabling end of isolation on day 6 after symptom onset (or positive test, if asymptomatic) for those with symptom improvement and ability to mask through day 10. 1 However, some individuals still carry culturable virus beyond day 5. 2 Rapid antigen test (RAT) positivity correlates with higher SARS-CoV-2 viral load and the ability to culture replication-competent virus, 3, 4 and has been considered a proxy for contagiousness. In January 2022, CDC updated its guidance to allow RAT towards the end of the 5-day isolation. A negative test permits cessation of isolation, while a positive result extends isolation through day 10. The impact of utilizing a "test-to-return" (TTR) program in school districts is unknown. In January 2022, a public school district in eastern Massachusetts initiated a TTR program. Students and staff isolating for COVID-19 infection could return on day 6-10 if afebrile without antipyretics, with symptom improvement, and with a negative RAT conducted by school staff. Participants with a positive RAT and those who declined TTR maintained isolation until day 11. Eligible individuals could take a school-administered test once between days 5-9. . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) The copyright holder for this preprint this version posted February 15, 2022. ; https://doi.org/10.1101/2022.02.11.22270843 doi: medRxiv preprint Data from all SARS-CoV-2 cases reported to the district with onset between December 27, 2021 and January 24, 2022 were included. Staff or student, grade level, presence of symptoms at any time during illness, date of symptom onset, date and type of initial positive test, vaccination status, and date and result of school-administered RAT for TTR participants were recorded. Day 0 of infection was considered the date of symptom onset if symptomatic or date of initial positive test, whichever came first. Eligibility for TTR and return to school was calculated forward from day 0. Positivity rates were calculated for the entire cohort and compared by grade level, type of initial test, vaccination status, presence of symptoms during illness, and day of infection on which TTR was conducted (chi square tests, R software). 5 Data among staff cases were insufficient for analysis. Cases were reported among 636 students ( Figure 1 ). . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 15, 2022. ; https://doi.org/10.1101/2022.02.11.22270843 doi: medRxiv preprint In a public school district during the Omicron surge, 31% of students with SARS-CoV-2 infection had a positive RAT 5-9 days after symptom onset or positive test, despite symptom improvement. This proportion is similar to model predictions 6 and observed results in health care workers. 7 Ever-symptomatic students were more likely to have a positive TTR than students who remained asymptomatic (43 vs. 17%). This study is subject to several limitations. First, students had only one opportunity to participate in TTR; some may have pre-tested or delayed TTR to ensure a negative schooladministered test. If all persons meeting time and symptom criteria had tested on day 5 or 6, the positivity rate would likely have been higher. Second, the correlation between RAT and culture-positivity is not yet understood for the Omicron variant, although preliminary data suggests that RAT remains sensitive when viral load is high by RT-PCR. 8 Implementation of TTR programs in schools has both advantages and costs. Compared to schools that allow return on day 6 without TTR, schools with TTR programs may have fewer school-associated transmissions, but more missed school days. However, as an alternative to isolation through day 10, TTR programs will reduce the number of missed school days. While TTR programs may identify those individuals who still carry replication-competent virus, spread in schools has been rare when masks are worn consistently; further, the risk of schoolassociated transmission during days 6-10 is not known. When return occurs prior to day 11 . CC-BY-NC-ND 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted February 15, 2022. ; https://doi.org/10.1101/2022.02.11.22270843 doi: medRxiv preprint Updates and Shortens Recommended Isolation and Quarantine Period for General Population Viral cultures for Coronavirus Disease 2019 infectivity assessment: a systematic review Antigen-Based Testing but Not Real-Time Polymerase Chain Reaction Correlates with Severe Acute Respiratory Syndrome Coronavirus 2 Viral Culture Safety, tolerability and viral kinetics during SARS-CoV-2 human challenge R: A language and environment for statistical computing. R Foundation for Statistical Computing COVID-19 self-isolation changes: scientific summary High Rates of Rapid Antigen Test Positivity After 5 days of Isolation for COVID-19 Title: Direct Comparison of SARS Co-V-2 Nasal RT-PCR and Rapid Antigen Test (BinaxNOW TM ) at a Community Testing Site During an Omicron Surge without TTR, districts should assume that some students could still be infectious. For students on days 6-10, strict adherence to masking (consistent with CDC guidance) and safe distance during unmasked periods, including lunchtime, are essential. Page 7 b Chi-square test for categorical variables (grade, location, vaccination status, symptoms); chi-square test of trend used for time-dependent variables (TTR day from first positive test or first symptoms) c Elementary school: Kindergarten through grade 5; Middle school: grades 6 through 8; High school: grades 9 through 12 d Initial positive test refers to the test at COVID-19 diagnosis, not TTR. The district participates in a pooled testing program in which asymptomatic students are screened through pooling multiple samples together, with positive cases identified through deconvolution of the positive pool. e Fully vaccinated defined as two doses of an mRNA vaccine or one dose of the J&J vaccine f Day of TTR is calculated forward from day 0, defined as the date of positive test or date of symptom onset, whichever came first.