Preplanned Studies: Willingness of the General Public to Receive A COVID-19 Vaccine Booster — China, April–May 2021

On October 11, 2021, the strategic advisory group of experts (SAGE) of the World Health Organization (WHO) recommended that an additional dose of coronavirus disease 2019 (COVID-19) vaccine should be offered to moderately and severely immunocompromised people and to those aged 60 and over who were previously immunized with Sinovac or Sinopharm inactivated vaccines (1). The National Health Commission of the People’s Republic of China (NHC) and the United States Centers for Disease Control Advisory Committee on Immunization Practices (ACIP) are planning a COVID-19 vaccine booster so that vaccinated people can maintain protection over the coming months (2-3). Numerous studies have shown that vaccination willingness is influenced by a variety of factors and that it changes over time (4-5). It is necessary to understand the public’s willingness to receive a COVID-19 vaccine booster. Identifying factors that influence booster vaccine acceptance will aid in determining who is most likely to accept a booster dose.

Online questionnaires were completed by 2,047 vaccinated Chinese adults in April and May 2021. Respondents’ sociodemographic characteristics, attitudes towards vaccination, and attitudes towards a COVID-19 vaccine booster were collected. All data were analyzed using R statistical software (version 4.0.3, R Core Team, Vienna, Austria). Logistic regression models were built to identify factors associated with respondents’ acceptance of a COVID-19 vaccine booster. The odds ratio (OR) and its corresponding 95% confidence interval (CI) were calculated.

Of the respondents, 75.2% reported they planned to receive a booster shot. Respondents who expressed significantly higher acceptance of a booster dose tended to be aged 25–54 years old, male, non-healthcare workers, and less educated. Moreover, those who had been vaccinated against influenza (OR=1.26, 95% CI: 1.01–1.57), who believed herd immunity would be effective against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (OR=3.58, 95% CI: 2.69–4.77), or who reported reduced anxiety after vaccination (OR=1.27, 95% CI: 1.02–1.59) were more likely to report planning to receive a booster dose.

Based on these results, it seems that a booster shot of the COVID-19 vaccine could be widely accepted in China. Communicating to the public the effectiveness of COVID-19 vaccines and the impact of COVID-19 infection on one’s health could increase individuals’ willingness to receive a booster dose.

In April and May 2021, an online questionnaire was disseminated via WeChat, a Chinese multipurpose social media app. Using WeChat moments, which spread questionnaires by snowballing, 1,656 respondents were recruited. To reduce the risk of bias due to starting with a single sample source, 403 additional respondents were recruited via the Tencent questionnaire sample database. This database contains over 1 million people with verified personal information, and we used the recruitment service to recruit subjects aged ≥18. Incomplete questionnaires were excluded. The final sample consisted of 2,047 respondents. Respondents’ sociodemographic characteristics, flu vaccination history, attitudes towards herd immunity, anxiety levels after initial vaccination, acceptance of a booster shot, and antibody tests were collected. The study was approved by Peking University Third Hospital Medical Science Research Ethics Committee (No. 2021-184-01).

The age- and gender-standardized acceptance rate of a COVID-19 vaccine booster was calculated using the 2010 population census of China as the reference (6). Logistic regression models were built to identify factors influencing COVID-19 vaccine booster acceptance (event: receiving COVID-19 vaccine booster when available). All data were analyzed using R statistical software. AP-value <0.05 was considered statistically significant.

Of the 2,047 vaccinated respondents (Table 1), 1,540 (75.2%) reported that they planned to receive a COVID-19 vaccine booster shot when it was available. The age- and gender-standardized acceptance rate was 75.8% (Table 2). In addition, 1,257 (81.6% of those who planned to receive the booster shot) reported that they would receive antibody tests, which could help to determine the effectiveness of the booster dose.

COVID-19 vaccine booster acceptance rate was highest among adults aged 45–54 years (81.2%) and lowest among adults aged ≥65 years (69.6%). Male respondents were more likely than female respondents to accept a COVID-19 vaccine booster (80.2%vs.72.2%), and those who were not healthcare workers were more likely to accept a booster dose than healthcare workers (79.3%vs.67.0%). Respondents who held a bachelor’s degree or below were more likely to accept a booster dose (68.9%, 74.5%, 83.3%,vs.85.4%). Vaccine booster acceptance was slightly higher among respondents who earned <5,000 CNY per month (77.7%vs.73.6%). Respondents who lived in rural areas were more likely to accept a booster dose (83.1%vs.74.1%). Moreover, those who had been vaccinated against influenza (77.7%vs.73.4% who had not been), who believed herd immunity would be effective against SARS-CoV-2 (78.9%vs.47.5% who did not believe this), and who reported reduced anxiety after vaccination (77.0%vs.71.7% who did not report this) were more likely to accept a booster dose.

The multiple logistic regression model identified the people most likely to get the booster dose as soon as it was available (Table 3). Those who expressed significantly higher acceptance of a booster dose included respondents who were: 25–34 years old (OR=2.06, 95% CI: 1.09–3.91); 35–44 years old (OR=2.24, 95% CI: 1.18–4.28); 45–54 years old (OR=2.07, 95% CI: 1.09–3.94); male (OR=1.33, 95% CI: 1.05–1.67); and non-healthcare workers (OR=1.50, 95% CI: 1.17–1.92). Booster shot acceptance was also higher among those who had: a junior high school level of education or below (OR=2.64, 95% CI: 1.50–4.62); a high school level of education (OR=2.12, 95% CI: 1.34–3.35); and who had been vaccinated against influenza (OR=1.26, 95% CI: 1.01–1.57). Finally, those who believed herd immunity would be effective against SARS-CoV-2 or who reported reduced anxiety after vaccination were more likely to accept a booster dose (OR=3.58, 95% CI: 2.69–4.77 and OR=1.27, 95% CI: 1.02–1.59, respectively).