Factors associated with vaccination intention and uptake over time in a sample of older Australians

This study sought to identify the behavioural and social drivers of vaccination in 16,745 older Australians. We analysed and compared influences on COVID-19 vaccination intention and uptake using prospectively collected survey data from the Sax Institute's 45 and Up Study. Vaccination intention increased with older age (adjusted odds ratio [aOR]:1.03; 95 % confidence interval [CI]: 1.01-1.04; p = .002), a belief that the vaccine is important for the person's own health (aOR: 5.17; 95 % CI: 4.23-6.24; p < .001), is safe (aOR:2.64; 95 % CI: 2.19-3.2; p < .001), and trusted by the person (aOR:6.79; 95 % CI: 5.59-8.26 p < .001); concern about contracting COVID-19 (aOR:1.78; 95 % CI: 1.47-2.17; p < .001); having enough information about COVID-19 vaccines (aOR:1.99; 95 % CI: 1.65-2.29; p < .001); a belief that most adults will receive a COVID-19 vaccine (aOR:2.31; 95 % CI: 1.93-2.77; p < .001); and a belief that family and friends wanted the person to receive a COVID-19 vaccine (aOR:6.07; 95 % CI: 5.06-7.27; p < .001). The same factors contributed to increased vaccine uptake, with the exception of age and the belief that the person had enough information about the vaccine. Concern that the vaccine will cause a serious reaction was associated with both lower intention (aOR:0.35; 95 % CI: 0.29-0.43; p < .001) and lower uptake (aOR:0.61; 95 % CI: 0.46-0.81; p < .001) while lower intention was also associated with low decisional autonomy (aOR:0.37; 95 % CI: 0.22-0.62; p < .001). Intentions changed over time and a change towards vaccination was associated with perceptions of vaccine safety. Access barriers played a role in the non-vaccination of otherwise intending older Australians. Messaging that is adaptive to safety concerns, emphasises vaccine benefits, leverages social norms, and targets people who make decisions for older Australians may be helpful for influencing vaccination intentions and increasing vaccine uptake.