Importance: To cope with the continuing coronavirus disease 2019 (COVID-19) pandemic, state and local officials need information on the effectiveness of policies aimed at curbing disease spread, as well as state-specific characteristics, like the racial mix, associated with increased risks related to the disease. Objective: To investigate whether state-imposed stay-at-home orders (SAHOs) and the proportion of African American population in a state were associated with the state-level COVID-19 cases. Design, Setting, and Participants: This cross-sectional study used daily, state-level data on COVID-19 cases, tests, and fatalities from the COVID Tracking Project. Data from March 1 to May 4, 2020, for all states (except Washington state) as well as the District of Columbia were used. Exposures: The key exposure variables were state-level SAHO (1 if in place, 0 otherwise), and proportion of state population who are African American. Main Outcomes and Measures: The primary outcome was daily cumulative COVID-19 case rates. A secondary outcome was subsequent COVID-19 fatality rates, derived using mean cumulative fatality rates 21 to 28 days after each date. Multivariate regression models were estimated. Results: The final sample included 3023 pooled state- and day-level observations. The mean (SD) cumulative positive case rate was 103.186 (200.067) cases per 100â¯000 state population, the mean (SD) cumulative test rate was 744.23 (894.944) tests per 100â¯000 state population, and the mean (SD) subsequent cumulative fatality rate was 12.923 (21.737) deaths per 100â¯000 state population. There was a negative association of SAHOs with cumulative case rates (ß = -1.166; 95% CI, -1.484 to -0.847; P < .001) and subsequent fatality rates (ß = -0.204; 95% CI, -0.294 to -0.113; P < .001). Estimation analyses indicated that expected cumulative case rates would have been more than 200% higher and fatality rates approximately 22% higher if there were no SAHOs, as compared with SAHOs fully in place. A higher proportion of African American population was associated with higher case rates (ß = 0.045; 95% CI, 0.014 to 0.077; P = .001) and fatality rates (ß = 0.068; 95% CI, 0.044 to 0.091; P < .001). Conclusions and Relevance: In this cross-sectional study, SAHOs were associated with reductions in COVID-19 case rates. These findings could help inform policy makers to address the continued COVID-19 pandemic in the US. The proportion of African American population was positively associated with COVID-19 case rates, and this state-level finding adds to evidence from existing ecological studies using county-level data on racial disparities in COVID-19 infection rates and underlines the urgency of better understanding and addressing these disparities.
Association of State Stay-at-Home Orders and State-Level African American Population With COVID-19 Case Rates