Prevalence and factors associated with SARS-CoV-2 vaccine hesitancy: a population-based survey in Hong Kong

Abstract

Purpose: Without an effective cure, vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) appears to be the most promising means to end the coronavirus disease (COVID-19) pandemic [1]. Vaccine hesitancy, defined as delays of refusal to accept the vaccine [2], would likely undermine efforts to achieve herd immunity and curb SARS-CoV-2 transmission. In a population-representative sample of Hong Kong residents in Hong Kong, we examined the prevalence and factors associated with SARS-CoV-2 vaccine hesitancy. Methods: Data were drawn from a population-based, dual-frame (landline and mobile) cross-sectional survey conducted from April 9 to 23, 2020, about 2 to 4 weeks after the peak of the second wave of outbreak in Hong Kong [3]. The methods and other findings from the survey have been published elsewhere [4]. Participants were Chinese-speaking Hong Kong residents aged 18 years or older randomly sampled by landline telephone (random digit dialling) and from a representative panel of 100,000 mobile phone users in Hong Kong. Participants were asked “if a vaccine against SARS-CoV-2 becomes available, would you take it?” with response options of “Yes”, “No”, or “Undecided”. Other measures included knowledge of the major mode of SARS-CoV-2 transmission, perceived danger of COVID-19, and perceived risk of contracting SARS-CoV-2 in the coming 6 months. To improve representativeness, prevalence estimates were weighted by the sex, age, and education distributions of the general adult population. Multivariable partial proportional odds model[5] was used to calculate the odds ratio (OR) of SARS-CoV-2 vaccine hesitancy in relation to sociodemographic factors, chronic disease status, smoking, and alcohol drinking behaviors, with a higher OR indicating greater hesitancy. The associations of knowledge and perceptions of COVID-19 with vaccine hesitancy were also examined. Results: Of the 1501 participants (response rate: 61.5%), 672 (53.6%) were females and 748 (48.5%) aged 50 years or older. Overall, 45.3% (95% CI 42.3–48.4%), had intentions to receive SARS-CoV-2 vaccine after it becomes available, 29.2% (26.5–32.1%) were undecided, and 25.5% (22.9–28.2%) had no intention. The most common reason for vaccine hesitancy (undecided or no intention) was “worry about the side effects of the vaccine” (56.5%). Multivariable analyses showed higher vaccine hesitancy in male and older participants, those with no chronic disease, current smokers, and non-alcohol drinkers (all P <0.05). After adjusting for these factors and education level, inadequate knowledge of SARS-CoV-2 transmission (adjusted ORs ranged from 1.27 to 2.63; P<0.05) and lower perceived danger of COVID-19 (adjusted ORs ranged from 1.62 to 2.47; P<0.001) were significantly associated with SARS-CoV-2 vaccine hesitancy. Conclusion: In this population-based survey in Hong Kong, less than half (45.3%) of the participants intended to vaccinate against SARS-CoV-2 when available. This was in stark contrast to the findings from a global survey of 19 countries conducted in June 2020, which found that 71.5% of participants were willing to take the SARS-CoV-2 vaccine [6]. Vaccination promotion campaigns need to consider sociodemographic variations in vaccine hesitancy and address inadequate knowledge about SARS-CoV-2 transmission and low perceived danger of COVID-19 to increase vaccination uptake.