Seasonal Influenza (Flu) Vaccine Uptake Among United States (U.S.) Adults

Abstract

Influenza viruses infect the nose, throat, and lungs, causing flu, a contagious respiratory illness resulting in mild to severe illness and possibly death. The annual flu vaccine is the most effective prevention method to decrease the risk of getting the flu and its severe health complications. However, the flu vaccine coverage among adults (18+ years) was 48.4% in the 2019-2020 flu season, still lower than the Healthy People’s 2030 target goal of 70%. The purpose of this dissertation was to investigate the differences in flu vaccination uptake associated with sociodemographic factors among U.S. adults (18+ years of age) from a regional and a national sample. The literature review summarized the sociodemographic factors – sex, age, education level, income level, employment status, insurance coverage, marital status, presence of chronic health conditions, racial and ethnic minority groups, and urbanization levels of residence – that influence flu vaccine uptake in U.S. adults. Then, two cross-sectional studies examined the relationship between sociodemographic factors – race/ethnicity; interaction between race/ethnicity and urbanization level of residence; interaction between race/ethnicity and income – and flu vaccine uptake and analyses were performed using logistic regression with interaction effects models while controlling for survey respondent characteristics. The first study found that among adults living in the greater Brazos Valley region of Texas who participated in the 2019 Brazos Valley Health Assessment, Hispanics were more likely to receive the flu vaccine than non-Hispanic Whites. Also, the interaction between race/ethnicity and urban-rural county designation was not significantly associated with flu vaccination uptake. The second study found that among adults living in the U.S. who participated in the 2019 and 2020 National Health Interview Survey, respectively, Non-Hispanic Black/African Americans were less likely to receive the flu vaccine than non-Hispanic Whites, and Non-Hispanic Asians were more likely to receive the flu vaccine than non-Hispanic Whites. In both survey years, the interaction between race/ethnicity and urban-rural county designation as well as the interaction between race/ethnicity and income were not significantly associated with flu vaccination uptake. Therefore, it is important to address flu vaccine inequity among U.S. minority populations and facilitating interventions aimed at increasing flu vaccine coverage.