Appealing to Americans' altruism is not enough to nudge them to accept novel vaccines.

Background: The role of altruism in the acceptance of novel preventive healthcare technologies like vaccines has not been thoroughly elucidated.

Methods: We 1:1 randomized n = 2004 Amazon Mechanical Turk (MTurk) participants residing in the USA into a control or treatment arm with vaccination decisions framed altruistically, to elicit their preferences for COVID-19 vaccination using web-based discrete choice experiments. We used conditional and mixed logit models to estimate the impact of framing decisions in terms of altruism on vaccination acceptance.

Results: Valid responses were provided by 1674 participants (control, n = 848; treatment, n = 826). Framing vaccination decisions altruistically had no significant effect on vaccination acceptance. Further, respondents' degree of altruism had no association with vaccination acceptance.

Limitations: The MTurk sample may not be representative of the American population. We were unable to ascertain concordance between stated and revealed preferences.

Conclusions And Implications: Framing vaccination decisions in terms of altruism does not appear to significantly influence vaccination acceptance and may not be an effective nudging mechanism to increase the uptake of novel vaccines. Instead, a favorable vaccination profile appears to be the primary driver of uptake.