Reducing COVID vaccine hesitancy by inducing a comparative mindset

Objective: To investigate if a behavioral nudge comprising a vaccination opportunity that employs a comparative probe first (i.e., which vaccine to take) versus the more commonly-used deliberative probe (i.e., willingness to take a vaccine), reduces vaccine hesitancy, while controlling for political partisanship.

Methods: In a randomized study, conducted on Amazon Mechanical Turk and Prolific, we varied the manner in which the vaccination offer is posed. In one group, participants were asked to compare which vaccine they would like to take (i.e., the comparative probe), while, in another group, participants were asked to deliberate whether they would like to take the vaccine (i.e., the deliberative probe). Participants' political preferences were also measured. The primary outcome variable was vaccine hesitancy.

Results: A LOGIT regression (N = 1736), was conducted to test the research questions. Overall, the comparative probe yielded a 6% reduction in vaccine hesitancy relative to the typical deliberative probe. Additionally, while vaccine hesitancy varies due to individual political views, the comparative probe is effective at reducing vaccine hesitancy even among the most vaccine hesitant population (i.e., Pro-Trump Republicans) by almost 10% on average.

Conclusions: Subtly changing the manner in which the vaccination offer is framed, by asking people to compare which vaccine to take, and not deliberate about whether they would like to take a vaccine, can reduce vaccine hesitancy, without being psychologically taxing or curtailing individuals' freedom to choose. The nudge is especially effective among highly vaccine hesitant populations such as Pro-Trump Republicans. Our results suggest a costless communication protocol in face-to-face interactions on doorsteps, in clinics, in Pro-Trump regions and in the mass media, that might protect 5 million Americans from COVID-19.