Inspecting the Mechanism

Abstract

Background. Influenza vaccination is strongly associated with socioeconomic status, but there is only limited evidence on the respective roles of socioeconomic differences in vaccination intentions versus corresponding differences in follow-through on initial vaccination plans for subsequent socioeconomic differences in vaccine uptake. Methods. Nonparametric mean smoothing, linear regression, and probit models were used to analyze longitudinal survey data on perceived influenza risks, behavioral vaccination intentions, and vaccination behavior of adults during the 2009–2010 influenza A/H1N1 (“swine flu”) pandemic in the United States. Perceived influenza risks and behavioral vaccination intentions were elicited prior to the availability of H1N1 vaccine using a probability scale question format. H1N1 vaccine uptake was assessed at the end of the pandemic. Results. Education, income, and health insurance coverage displayed positive associations with behavioral intentions to get vaccinated for pandemic influenza while employment was negatively associated with stated H1N1 vaccination intentions. Education and health insurance coverage also displayed significant positive associations with pandemic vaccine uptake. Moreover, behavioral vaccination intentions showed a strong and statistically significant positive partial association with later H1N1 vaccination. Incorporating vaccination intentions in a statistical model for H1N1 vaccine uptake further highlighted higher levels of follow-through on initial vaccination plans among persons with higher education levels and health insurance. Limitations. Sampling bias, misreporting in self-reported data, and limited generalizability to nonpandemic influenza are potential limitations of the analysis. Conclusions. Closing the socioeconomic gap in influenza vaccination requires multipronged strategies that not only increase vaccination intentions by improving knowledge, attitudes, and beliefs but also facilitate follow-through on initial vaccination plans by improving behavioral control and access to vaccination for individuals with low education, employed persons, and the uninsured.