Psychosocial factors affecting COVID-19 vaccine uptake in the UK: A prospective cohort study (CoVAccS - Wave 3).

Background: We investigated factors associated with COVID-19 vaccine uptake, future vaccination intentions, and changes in beliefs and attitudes over time. Methods: Prospective cohort study. 1500 participants completed an online survey in January 2021 (T1, start of vaccine rollout in the UK), of whom 1148 (response rate 76.5 %) completed another survey in October 2021 (T2, all UK adults offered two vaccine doses). Binary logistic regression analysis was used to investigate factors associated with subsequent vaccine uptake. Content analysis was used to investigate the main reasons behind future vaccine intentions (T2). Changes in beliefs and attitudes were investigated using analysis of variance. Findings: At T2, 90.0 % (95 % CI 88.2-91.7 %) of participants had received two doses of a COVID-19 vaccine, 2.2 % (95 % CI 1.3-3.0 %) had received one dose, and 7.4 % (95 % CI 5.9-8.9 %) had not been vaccinated. Uptake was associated with higher intention to be vaccinated at T1, greater perceived vaccination social norms, necessity of vaccination, and perceived safety of the vaccine. People who had initiated vaccination reported being likely to complete it, while those who had not yet received a vaccine reported being unlikely to be vaccinated in the future. At T2, participants perceived greater susceptibility to, but lower severity of, COVID-19 ( Interpretation: Targeting modifiable beliefs about the safety and effectiveness of vaccination may increase uptake.