Assessing COVID-19 Vaccine Booster Hesitancy Using the Modified 5C Scale in Zhejiang Province, China: A Cross-Sectional Study

Following the rollout of a booster campaign to promote immunity against COVID-19 in China, this study aimed to assess booster hesitancy among adults who were fully vaccinated with primary doses across Zhejiang Province. Firstly, the modified 5C scale developed by a German research team was assessed for reliability and validity via a pre-survey in Zhejiang Province. Then, a 30-item questionnaire was established to conduct online and offline surveys during 10 November to 15 December 2021. Demographic characteristics and information on previous vaccination experience, vaccine type of primary doses, attitudes towards booster doses and awareness of SARS-CoV-2 infection were collected. Chi-square tests, pairwise comparison and multivariate logistic regression were performed in data analysis. In total, 4039 valid questionnaires were analyzed, with booster hesitancy of 14.81%. Dissatisfaction with previous vaccination experience of primary doses (ORs = 1.771 similar to 8.025), less confidence in COVID-19 vaccines (OR = 3.511, 95%CI: 2.874 similar to 4.310), younger age compared to the elderly aged 51-60 years old (2.382, 1.274 similar to 4.545), lower education level (ORs = 1.707 similar to 2.100), weaker awareness of social responsibility of prevention and control of COVID-19 (1.587, 1.353 similar to 1.859), inconvenience of booster vaccination (1.539, 1.302 similar to 1.821), complacency regarding vaccine efficacy as well as self-health status (1.224, 1.056 similar to 1.415) and excessive trade-offs before vaccination (1.184, 1.005 similar to 1.398) were positively associated with booster hesitancy. Therefore, intelligent means should be strengthened to optimize vaccination services. More influential experts and other significant figures should be supported to promote timely evidence-based information via various media platforms to reduce public hesitancy and increase booster uptake.