LAUSR

OBJECTIVES We evaluated the impact of a test-to-stay (TTS) program on within-school transmission and missed school days in optionally masked kindergarten through 12th grade schools during a period of high community severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. METHODS Close contacts of those with confirmed SARS-CoV-2 infection were eligible for enrollment in the TTS program if exposure to a non-household contact occurred between 11/29/2021 and 01/28/2022. Consented participants avoided school exclusion if they remained asymptomatic and rapid antigen testing at pre-specified intervals remained negative. Primary outcomes included within-school tertiary attack rate (test positivity among close contacts of positive TTS participants) and school days saved among TTS participants. We estimated the number of additional school-acquired cases resulting from TTS and eliminating school exclusion. RESULTS A total of 1675 participants tested positive or received at least one negative test between days 5 and 7, and completed follow-up; 92% were students and 91% were exposed to an unmasked primary case. We identified 201 positive cases. We observed a tertiary attack rate of 10% (95% CI 6-19%) and 7,272 (89%) of potentially missed days were saved through TTS implementation. We estimated one additional school-acquired case for every 21 TTS participants remaining in school buildings during the entire study period. CONCLUSIONS Even in the setting of high community transmission, a TTS strategy resulted in substantial reduction in missed school days in optionally masked schools.