Factors associated with perceptions of influenza vaccine safety and effectiveness among adults, United States, 2017-2018.

Background: Annual vaccination against seasonal influenza is widely recognized as the primary intervention method in preventing morbidity and mortality from influenza, but coverage among adults is suboptimal in the United States. Safety and effectiveness perceptions regarding vaccines are consistently cited as factors that influence adults' decisions to accept or reject vaccination. Therefore, we conducted this analysis in order to understand sociodemographic, attitude, and knowledge factors associated with these perceptions for influenza vaccine among adults in three different age groups.

Methods: Probability-based Internet panel surveys using nationally representative samples of adults aged ≥19 years in the United States were conducted during February-March of 2017 and 2018. We asked respondents if they believed the influenza vaccine was safe and effective. We calculated prevalence ratios using chi-square and pairwise t-tests to determine associations between safety and effectiveness beliefs and sociodemographic variables for adults aged 19-49, 50-64, and ≥65 years.

Results: Survey completion rates were 58.2% (2017) and 57.2% (2018); we analyzed 4597 combined responses. Overall, most adults reported the influenza vaccine was safe (86.3%) and effective (73.0%). However, fewer younger adults reported positive perceptions compared with older age groups. Respondents who believed the vaccine was safe also reported it was effective.

Conclusions: Generally, adults perceived the influenza vaccine as safe and effective. Considering this, any improvements to these perceptions would likely be minor and have a limited effect on coverage. Future research to understand why, despite positive perceptions, adults are still choosing to forego the vaccine may be informative.