Exploring Spatially Varying Associations of COVID-19 Rates with Contextual Socioeconomic, Health, and Environmental Factors under Partial Population Coverage of Vaccination: A Retrospective Ecological Study in Georgia, USA.

A good understanding of the associations of COVID-19 infection and mortality with contextual factors when vaccines were not widely available is necessary for human societies to be better prepared for future outbreaks of infectious diseases. This retrospective ecological study aimed to explore the spatially varying associations of COVID-19 incidence, death, and case fatality rates with contextual socioeconomic, health, and environmental factors during the period of partial population coverage of vaccination at county level in the state of Georgia, USA. The associations of COVID-19 rates and contextual factors were analyzed using geographically weighted regression (GWR), compared with ordinary least squares regression (OLS) analysis. OLS results showed that most factors were significantly associated with COVID-19 death rate and case fatality rate, but not incidence rate. GWR results demonstrated that the associations of all three COVID-19 rates with factors varied across space: A factor might have a significant positive, significant negative, or nonsignificant association with each rate in certain counties. Most factors for poor health outcomes were significantly associated with higher risks of COVID-19 infection and mortality in more counties compared to non-significant or inverse associations. The spatially varying associations for some contextual factors were related to the socioeconomic and urbanization characteristics of counties. Some factors also affected COVID-19 infection and mortality differently. For example, persons aged 65 and older percentage was not a significant risk factor of COVID-19 infection in most counties, but it was the most spatially consistent risk factor of COVID-19 death in Georgia; fully vaccinated percentage was a more significant indicator of reducing COVID-19 infection in rural counties compared to urban and suburban areas. This study provides useful information for public health agencies and professionals to make and implement more specific and targeted local health policies.