Applying two behavioral theories to predict the willingness to receive COVID-19 vaccine booster in the elderly: A cross-sectional study

BACKGROUND: The COVID-19 vaccination booster can effectively protect the elderly from infection while also lowering the risk of serious illness and death. However, barriers remain in willingness of the elderly to boost vaccination. OBJECTIVE: Using the protection motivation theory (PMT) and the theory of planned behavior (TPB), to study the factors that influence willingness of the elderly to get the COVID-19 vaccine booster. METHODS: The elderly who visited three randomly selected medical institutions in Nanjing's core urban region between March and April 2022 were chosen as study participants. A face-to-face survey was conducted using purposeful sampling and a self-designed questionnaire. The questionnaire contained sociodemographic characteristics, the elderly's willingness to obtain a COVID-19 vaccine booster, and psychosocial cognitive components based on the PMT and TPB. SmartPLS 3.0 was used to conduct structural equation modeling. RESULTS: 214 participants were included in the analysis. The combined model of the two behavioral theories explained the willingness to accept COVID-19 vaccine booster well with R(2) of 0.490. Self-efficacy (β = 0.315) was the strongest predictor of vaccine booster willingness. Subjective norms (β = 0.160), perceived severity (β = 0.157), and perceived vulnerability (β = 0.159) also showed positive effects on vaccine booster willingness, while response cost (β = −0.143) had a negative effect on the willingness. No significant association between attitudes, response efficacy and the willingness was discovered. CONCLUSION: The willingness of the elderly to receive the COVID-19 vaccine booster was affected by psychosocial cognitive factors. This study supports the applicability of the PMT and TPB models to interpret the willingness of the elderly in such areas.