ABSTRACT
Interrupted time series analyses were conducted to
measure the impact of
social distancing policies (instituted on March 22, 2020) and of subsequent mandatory masking in the
community (instituted on May 4, 2020) on the
incidence and
effective reproductive number of COVID-19 in São Paulo
State,
Brazil. Overall, the impact of
social distancing both on
incidence and Rt was greater than the incremental effect of mandatory masking. Those findings may reflect either a small impact of
face masking or the loosening of
social distancing after mandatory use of
masks.