Effect of physical distancing on Covid-19 incidence in Brazil: does the strictness of mandatory rules matter?

This study aims to examine the association between physical distancing measures and coronavirus disease 2019 (COVID-19) incidence among Brazilian states. We divided the methodology was divided into three steps. In the first step, we used nationwide global positioning system daily data to estimate country and state-level physical distancing and examined the association with COVID-19 incidence through a Generalized Additive Model. Secondly, using National Household Sample Survey COVID19 data, a cluster analysis categorized the Brazilian states into different categories of physical distancing policies promoting adoption and political inclination of their governments. Finally, through a Poisson Regression Model, we examined the association of state physical distancing with variables related to the socio-economic situation, test coverage and early adoption of policies promoting physical distancing of each state. Physical distancing effects on reduction of COVID-19 spread are heterogeneous among states. Estimation of incidence rate ratio (IRR) suggests that in a scenario of 100% of social isolation incidence of COVID-19 will have reached approximately only 2.6% of the magnitude compared to when there is no social isolation for Brazil [95% confidence interval (CI) 0.8-8.3]. Only a 10% increase in Social Isolation Index in the country could have reflected in a 30.5% decrease in number of cases in 14 days. Adoption of physical distancing was associated with test coverage (IRR 0.976, 95% CI 0.973-0.979), home office (IRR 1.042, 95% CI 1.039-1.046), informal work proportion (IRR 0.961, 95% CI 0.958-0.965), political spectrum (IRR 0.961, 95% CI 0.958-0.965) and early moment of restrictive politics implementation (IRR 1.017, 95% CI 1.013-1.021). Physical distancing measures play a crucial role in mitigating the pandemic's spread. These analyses are crucial to support government decisions and improve the community's adherence to preventive measures.