Factors Associated with Influenza Vaccination in Japanese Elderly Outpatients

Background: Elderly patients benefit from influenza vaccination, but the number of Japanese elderly patients who are vaccinated is insufficient. Several factors are associated with influenza vaccination acceptance, but little is known about Japanese elderly outpatients. The purpose of this study was to examine factors associated with influenza vaccination in elderly outpatients in Japan.

Methods: During the 2017-2018 influenza season, outpatients from one hospital and one clinic in Kitaibaraki City, Ibaraki, Japan, participated in this study. Patients answered a self-report questionnaire exploring factors such as their vaccination status during the 2017-2018 season, past influenza vaccination, perceived susceptibility to influenza and adverse events of the vaccine, perceived vaccine efficacy, physician recommendations. Multivariable logistic regression analyses were conducted to identify factors associated with vaccination.

Results: Of 377 patients, 316 (83.8%) responded, and the vaccination rate was 57%. Eighty-three patients (27.0%) reported that their physician recommended the influenza vaccine. In multivariate analysis, influenza vaccination was associated with higher age (odds ratio (OR) 1.09, 95% confidence interval (CI) 1.03-1.14), physician recommendations (OR 2.49, 95% CI 1.18-5.25), low perceived susceptibility to vaccine-related adverse events (OR 0.33, 95% CI 0.15-0.74), and belief in vaccine efficacy (OR 4.73, 95% CI 2.08-10.8).

Conclusions: Influenza vaccination was associated with belief in vaccine efficacy, perceived susceptibility to vaccine-related adverse events, physician recommendations, and older age. Increasing the frequency of physician recommendations may lead to increased vaccination coverage.