Predictors of COVID-19 vaccine uptake: an online three-wave survey study of US adults.

Background: To effectively promote vaccine uptake, it is important to understand which people are most and least inclined to be vaccinated and why. In this study, we examined predictors of COVID-19 vaccine uptake and reasons for non-vaccination.

Methods: We conducted an online English-language survey study in December-2020, January-2021, and March-2021. A total of 930 US respondents completed all surveys. Multiple logistic regression models were run to test whether the early vaccine eligibility, demographic factors, and psychological factors predict getting at least one dose of a COVID-19 vaccination in January-2021 and in March-2021.

Results: The proportion of respondents who received ≥ 1-dose of a COVID-19 vaccine increased from 18% (January) to 67% (March). Older age predicted vaccine uptake in January (OR = 2.02[95%CI = 1.14-3.78], p < .001) and March (10.92[6.76-18.05], p < .001). In January, additional predictors were higher numeracy (1.48[1.20-1.86], p < .001), COVID-19 risk perceptions (1.35[1.03-1.78], p = .029), and believing it is important adults get the COVID-19 vaccine (1.66[1.05-2.66], p = .033). In March, additional predictors of uptake were believing it is important adults get the COVID-19 vaccine (1.63[1.15-2.34], p = .006), prior COVID-19 vaccine intentions (1.37[1.10-1.72], p = .006), and belief in science (0.84[0.72-0.99], p = .041). Concerns about side effects and the development process were the most common reasons for non-vaccination. Unvaccinated respondents with no interest in getting a COVID-19 vaccine were younger (0.27[0.09-0.77], p = .016), held negative views about COVID-19 vaccines for adults (0.15[0.08-0.26], p < .001), had lower trust in healthcare (0.59[0.36-0.95], p = .032), and preferred to watch and wait in clinically ambiguous medical situations (0.66[0.48-0.89], p = .007).

Conclusions: Evidence that attitudes and intentions towards COVID-19 vaccines were important predictors of uptake provides validation for studies using these measures and reinforces the need to develop strategies for addressing safety and development concerns which remain at the forefront of vaccine hesitancy.