Association of country-wide coronavirus mortality with demographics, testing, lockdowns, and public wearing of masks.

Background. Wide variation between countries has been noted in per-capita mortality from the disease (COVID-19) caused by the SARS-CoV-2 virus. Determinants of this variation are not fully understood. Methods. Potential predictors of country-wide per-capita coronavirus-related mortality were studied, including age, sex ratio, temperature, urbanization, viral testing, smoking, duration of infection, lockdowns, and public mask-wearing norms and policies. Multivariable linear regression analysis was performed. Results. In univariate (but not multivariable) analyses, prevalence of smoking, per-capita gross domestic product, and colder average country temperature were positively associated with coronavirus-related mortality. In a multivariable analysis of 183 countries, urbanization, the duration of the infection in the country, and percent of the population at least 60 years of age were all positively associated with per-capita mortality, while duration of mask-wearing by the public was negatively associated with mortality (all p<0.001). In countries with cultural norms or government policies supporting public mask-wearing, per-capita coronavirus mortality increased on average by just 5.4% each week, as compared with 48% each week in remaining countries. In the multivariable analysis, lockdowns tended to be associated with less mortality (p=0.31), and per-capita testing with higher reported mortality (p=0.26), though neither association was statistically significant. Conclusions. Societal norms and government policies supporting the wearing of masks by the public are independently associated with less mortality from COVID-19.