Relationship Between COVID-19 Cases and Vaccination Rates in New York State Counties

Vaccines against SARS-CoV-2 have been developed with unprecedented speed. The phased introduction of vaccines may be serving to offset the impact of new viral variants and policy relaxation. In order to assess the impact of vaccination, we examined a snapshot of vaccination rates across counties in a single state, at a single time point, comparing them with population-adjusted case counts.

We calculated descriptive statistics and bivariate correlations for vaccination rates and cases across counties in New York State (NYS). We conducted a linear regression using cases/100K population per NYS county, frozen at a single snapshot in time, as the outcome variable, predicted by percentage of each county's population (completed series/two doses), controlling for county population.

Percentages with one dose and with two doses were highly correlated (r=.935, P<.001) with one another. Both the one dose and two dose z rates were negatively correlated with cases per 100K population (not significant). Population size was strongly correlated with cases per 100K (r=.715, P<.001). The two-dose vaccination rate was a significant negative predictor of cases per 100K population in NYS counties (β= -.866, P=.031), with each percentage point of completed vaccination nearly equating to one case less in the daily count when controlling for county population size (β =2.732, P<.001).

While variants may impact vaccine effectiveness, current vaccination efforts are helping forestall some cases in NYS. Widespread vaccination is still an important goal. Primary care providers, public officials, and public health scientists should continue to urgently promote and support vaccination efforts.