Can a COVID-19 vaccine live up to Americans’ expectations? A conjoint analysis of how vaccine characteristics influence vaccination intentions

OBJECTIVE: A vaccine for the novel coronavirus (COVID-19) could prove critical in establishing herd immunity. While past work has documented the prevalence and correlates of vaccine refusal, I assess how a less explored topic -- properties of vaccines themselves (e.g., national origin, efficacy, risk of side effects) -- might influence vaccination intentions. This information can help public health officials preempt differential intentions to vaccinate, and inform health communication campaigns that encourage vaccine uptake. RATIONALE: Previous research suggests that Americans should be more likely to intend to vaccinate if presented with a US-made vaccine that carries a low risk of minor side effects, is highly effective, is administered in just one dose, and has spent significant time in development. METHODS: I administered a conjoint experiment (N = 5940 trials) in a demographically representative survey (N = 990) of US adults to assess how variation in vaccine properties influence self-reported public vaccination intentions. RESULTS: I find that respondents prefer vaccines that are US-made, over 90% effective, and carry a less than 1% risk of minor side effects. This is potentially problematic, as some leading vaccine candidates are produced outside the US, and/or may be more likely to produce minor side effects than respondents would otherwise prefer. Worryingly, intended vaccine refusal rates exceed 30% for a vaccine meeting these optimal characteristics. Encouragingly, though, Americans show no clear preference for vaccines administered in one dose, or developed in under a year, and do not appear to draw a distinction between weakened viral vs. mRNA-based vaccines. CONCLUSION: Americans’ preferences for a novel coronavirus vaccine may be at odds with the vaccine that ultimately hits the market, posing both policy and health communication challenges for vaccination uptake.