# Patterns of Influenza Vaccination Coverage in the United States from 2009 to 2015

## TL;DR

This study analyzed influenza vaccination patterns in the U.S. from 2009 to 2015, revealing that healthcare access significantly influences vaccination coverage among various populations, especially the elderly and children.

## Contribution

It provides a comprehensive ecological analysis of state-level influenza vaccination coverage and identifies healthcare access as a key factor influencing vaccination rates.

## Key findings

- Healthcare access positively correlates with vaccination coverage.
- Asthma prevalence in adults negatively affects elderly vaccination rates.
- Regional differences impact vaccination patterns.

## Abstract

Background: Globally, influenza is a major cause of morbidity, hospitalization and mortality. Influenza vaccination has shown substantial protective effectiveness in the United States. We investigated state-level patterns of coverage rates of seasonal and pandemic influenza vaccination, among the overall population in the U.S. and specifically among children and the elderly, from 2009/10 to 2014/15, and associations with ecological factors. Methods and Findings: We obtained state-level influenza vaccination coverage rates from national surveys, and state-level socio-demographic and health data from a variety of sources. We employed a retrospective ecological study design, and used mixed-model regression to determine the levels of ecological association of the state-level vaccinations rates with these factors, both with and without region as a factor for the three populations. We found that health-care access is positively and significantly associated with mean influenza vaccination coverage rates across all populations and models. We also found that prevalence of asthma in adults are negatively and significantly associated with mean influenza vaccination coverage rates in the elderly populations. Conclusions: Health-care access has a robust, positive association with state-level vaccination rates across different populations. This highlights a potential population-level advantage of expanding health-care access.