Factors in intention to get the COVID-19 vaccine change over time: Evidence from a two-wave US study

Public responses to the risks of both a novel emerging pandemic and of getting vaccinated against that disease affect both population health and wider societal relations, as illustrated by the COVID-19 pandemic. This study aimed to identify factors - including demographics, beliefs and attitudes about COVID-19 and its vaccines, trust of authorities - associated with vaccination intentions, as prior pandemic studies did not converge on explanations, and potential factors from risk analysis remained untested. It also tested whether and how such associations changed over time, as previous cross-sectional studies could not assess whether prior intentions entirely determined later intentions. A nationally representative sample of Americans was surveyed in late October 2020 (n = 1028), before vaccines became available in the U.S., and in February 2021 (n = 803), when 11% of U.S. residents had been vaccinated. The survey instrument asked about vaccination intentions and hypothesised factors in both waves. Perceived vaccine attributes (efficacy, riskiness, affect, dread), seasonal flu vaccination experience, and trust in authorities and belief in conspiracy theories were the strongest factors overall, particularly in Wave 2 (with Wave 1 intentions as a control); demographics were stronger factors when COVID-19 vaccines were still hypothetical. The strongest factors in vaccination intention concerned vaccine experience and vaccine beliefs and attitudes potentially influenced by education, and by trust and belief in conspiracy theories, likely more resistant to change. Further use of this novel longitudinal design, which revealed moderate differences in intention-predictive factors over time, is warranted in future research on vaccine hesitancy.