Assessment of Communication Strategies for Mitigating COVID-19 Vaccine-Specific Hesitancy in Canada

Ensuring widespread uptake of available COVID-19 vaccinations, each with different safety and efficacy profiles, is essential to combating the unfolding pandemic.

To test communication interventions that may encourage the uptake of less-preferred vaccines.

This online survey was conducted from March 24 to 30, 2021, using a nonprobability convenience sample of Canadian citizens aged 18 years or older, with quota sampling to match 2016 Canadian Census benchmarks on age, gender, region, and language. Respondents completed a 2-by-2-by-2 factorial experiment with random assignment of brand (AstraZeneca or Johnson & Johnson), information about the vaccine's effectiveness against symptomatic infection (yes or no), and information about the vaccine's effectiveness at preventing death from COVID-19 (yes or no) before being asked about their willingness to receive their assigned vaccine and their beliefs about its effectiveness.

Respondents were randomly assigned a vaccine brand (AstraZeneca or Johnson & Johnson) and information about the vaccine's effectiveness against symptomatic COVID-19 infection (yes or no) and at preventing death from COVID-19 (yes or no).

Respondents' self-reported likelihood of taking their assigned vaccine if offered (response categories: very likely, somewhat likely, not very likely, or not at all likely, scaled 0-1) and their beliefs about their assigned vaccine's effectiveness (response categories: very effective, somewhat effective, not very effective, or not at all effective, scaled 0-1) were measured.

A total of 2556 Canadian adults responded to the survey (median [IQR] age, 50 [34-63] years; 1339 women [52%]). The self-reported likelihood of taking an assigned AstraZeneca or Johnson & Johnson vaccine was higher for respondents given information about their assigned vaccine's effectiveness at preventing death from COVID-19 (b, 0.04; 95% CI, 0.01 to 0.06) and lower among those given information about its overall effectiveness at preventing symptomatic transmission (b, -0.03; 95% CI, -0.05 to 0.00), compared with those who were not given the information. Perceived effectiveness was also higher among those given information about their assigned vaccine's effectiveness at preventing death from COVID-19 (b, 0.03; 95% CI, 0.01 to 0.05) and lower among those given information about their assigned vaccine's overall efficacy at preventing symptomatic infection (b, -0.05; 95% CI, -0.08 to -0.03), compared with those who were not given this information. The interaction between these treatments was neither substantively nor statistically significant.

These findings suggest that providing information on the effectiveness of less-preferred vaccines at preventing death from COVID-19 is associated with more confidence in their effectiveness and less vaccine-specific hesitancy. These results can inform public health communication strategies to reduce hesitancy toward specific COVID-19 vaccines.