Impacts of Testing, Vaccination, and Immunity on COVID-19 Cases in Schools

Abstract

Abstract Massachusetts supported several testing programs to facilitate in-person learning in 2021-22. The aim of this state-wide, retrospective cohort study was to assess the impact of these testing programs and immunity on COVID-19 case rates in students. N=652,353 students (~ 59% of eligible population) at 2,141 schools consented to participate in in-school testing. High vaccination uptake and community immunity acquired via prior infection mitigated COVID-19 cases in elementary and secondary schools. High vaccination reduced the incidence of COVID-19 cases in elementary schools by 5.1% but protection waned after 8-10 weeks. During the delta period, higher cumulative community incidence rates were associated with higher case rates in schools; during the omicron period, this association reversed, such that schools in communities with lower levels of prior infection had higher rates of infection. Neither the test-to-stay modified quarantine program nor the pooled testing surveillance program were associated with substantial changes in cases.