The Relationship of Vaccine Uptake and COVID-19 Infections among Nursing Home Staff and Residents in Missouri (preprint)

ABSTRACT

IntroductionOlder adults living in communal spaces, such as nursing or retirement communities are at greater risk of infection due to close proximity to others, advanced aging-related or medical conditions, and engagement with staff that support multiple clients and facilities. Mobility between residents and facilities may result in staff acting as vectors of COVID-19 infection in these spaces. Vaccine uptake has been shown to markedly reduce the spread of COVID-19, yet there is little data on vaccine uptake and the continued COVID-19 risk among residents. MethodsData for this study were extracted from two publicly available. First, Centers for Medicaid and Medicare Services (CMS) public data included characteristics of nursing homes, weekly reported observations of residential COVID-19 cases, and COVID-19 vaccine coverage of staff and residents. Second, average weekly COVID-19 infection rate from Missouri Department of Health and Senior Services (MDHSS) were extracted and aggregated. A zero-inflated Poisson (ZIP) regression model was constructed to predict (1) if COVID-19 infections were reported, and if so, (2) the number of cases reported using a priori variables as predictors. ZIP regression was used due to the count nature of the outcome and due to the pre-determined overdispersion of observations when zero COVID-19 cases were reported during the study period. ResultsA total of 504 nursing homes were included in the study and 1124 COVID-19 infections were reported during the study period. As the percent of vaccinated staff increased, the risk of COVID-19 infections among residents significantly decreased. Percent of residents vaccinated was not significantly associated with whether COVID-19 cases were reported, nor the number of cases reported. Other factors, such as county COVID-19 rate and CMS staff rating, were significantly associated with COVID-19 cases in nursing homes. DiscussionThis study identified that nursing home staff, likely due to greater mobility, are important to prioritize in vaccination efforts to protect themselves and residents of their facilities from COVID-19 infections. Further, the CMS staff ratings were significant predictors of infection as well, which highlight the structural challenges that exist within and outside the context of a highly infectious and deadly pandemic. These results also provide insights to optimizing vaccination roll-out to best protect our communities most vulnerable residents.