Until now, researchers have not completely understood the association between overcrowded and multigenerational households in New York City and the risk of spreading COVID-19. Nathaniel Hupert, MD, MPH, associate professor of population health sciences; Said Ibrahim, MD, MBA, MPH, professor of population health sciences at the time of the study; Anjile An, MPH, programmer analyst for population health sciences; and colleagues across New York examined this in a new cohort study in Public Health. The researchers conducted a Bayesian ecological time series analysis at the ZIP Code Tabulation Area (ZCTA) level across the city from March 1 to 30, 2020. They found that 39,923 suspected COVID-19 cases were presented to emergency departments across 173 ZCTAs in NYC, with higher percentages of cases being from overcrowded and multigenerational housing (these risk factors were independent of one another). Social distancing measures that were first implemented at the beginning of the pandemic may have inadvertently but temporarily increased transmission risk and COVID-19 disease in these populations.