Differences in the Effectiveness of COVID-19 Vaccine Administration Between the Five New York City Boroughs: An Interrupted Time Series Analysis

Abstract

Background: Within New York City (NYC), certain communities have experienced greater rates of adverse COVID-19 outcomes. Current literature has evaluated the effectiveness of public health interventions during COVID-19 but fails to stratify across boroughs with varying demographic makeups. Understanding the effect of COVID-19 on different NYC communities may allow for the development of more efficacious public health policies that address populational disparities. Therefore, we compared trends in COVID-19 cases, hospitalizations, and deaths between the five NYC boroughs before and after the start of vaccine administration, using an interrupted time series analysis. Methods: Data was collected from the Department of Health and Mental Hygiene’s dataset on daily COVID-19 cases, hospitalizations, and deaths. Our interrupted time series began on June 8th, 2020 and analyzed data through July 3rd, 2021. The intervention in our analysis was the availability of vaccinations to New Yorkers aged 16 years or older, beginning April 6th, 2021. Changes between pre- and post-intervention outcome trends were compared across each of the boroughs. Results: In NYC as a whole, there was a significant decrease in the trend of cases, hospitalizations, and deaths following vaccinations. The greatest decreases in case trends were seen in the Bronx, Brooklyn, and Queens. Staten Island had a significantly greater decrease in hospitalizations, yet had the smallest change in deaths per unit time. In contrast, Brooklyn had a significantly greater decrease in death trends compared to all other boroughs. Conclusion: We demonstrate a significant decrease in the trends of cases, hospitalizations, and deaths in NYC following vaccinations, illustrating its effectiveness in mitigating the spread of the pandemic. However, such decreases varied between boroughs, potentially owing to demographic and population-based disparities. Variations in post-intervention death trends may be attributed to Brooklyn’s larger population and a higher percentage of unmet medical care. Furthermore, boroughs with the highest proportion of Black/Hispanic inhabitants and unemployment experienced the greatest rise in pre-intervention death trends. This may indicate a need to target such populations in future public health crises. Nevertheless, boroughs with the highest minority populations showed the greatest decrease in case and death trends, suggesting the vaccine’s effectiveness among underserved populations.