Limited impact of lifting universal masks on SARS-COV-2 transmission in schools: The crucial role of outcome measurements

ABSTRACT As the pandemic’s dynamics changed, many municipalities lifted face wearing requirement in school which was initially implemented to mitigate the transmission of COVID-19. This study examines the effects of lifting mask mandates on COVID-19 transmission within Massachusetts school districts. We first replicated previous research by Cowger et al. (2022) utilizing a Difference-in-Difference (DID) model. Then, we back project the case infection and calculate the Rt value to redo the DID analysis. However, when shifting the outcome measurement to the reproductive number (Rt), our findings suggest that lifting mask mandates can only significantly influence the Rt first two weeks post-intervention. This implies that while mask mandate plays a role in mitigation, its lifting does not drastically influence COVID-19 transmissibility in the long term.