The development of vaccines showing high efficacy against SARS-CoV-2 has offered a way to protect against the health effects of the virus. Yet national surveys suggest that willingness to vaccinate declined throughout 2020 and may be insufficient to provide population immunity.1-3 Public trust in the development of vaccines and the government approval process represents a potential crucial reason for this hesitancy. This study tested changes in trust in vaccination and vaccine hesitancy.
Participants were from 7 waves of the probability-based Understanding America Study (UAS) of US adults,2,4 conducted between October 14, 2020, and March 29, 2021. The UAS is an internet panel in which panel members are invited to complete questionnaires every 14 to 28 days; internet-connected tablets are provided to households if necessary. The response rate from panel members in this study was 75% to 79% (Supplement).
Participants were asked how likely they were to get vaccinated against the coronavirus and were classed as hesitant (unsure or somewhat/very unlikely to vaccinate) or willing to vaccinate (somewhat likely/very likely to vaccinate or already vaccinated). Participants were also asked to rate how much they trust “the governmental approval process to ensure the COVID-19 vaccine is safe for the public” and “the process in general (not just for COVID-19) to develop safe vaccines for the public” (1 [fully trust] to 4 [do not trust]). Responses to both questions were highly correlated (r = 0.84). Responses were reverse scored and combined to form a single indicator of public trust in vaccination (ranging from 0-6).
Logistic regression analysis with cluster robust SEs followed by the Stata 17 margins postestimation command was used to estimate percentage-point differences in the level of vaccine hesitancy between October 2020 and March 2021, with statistical significance defined as 2-sided P < .05. All analyses incorporated sampling weights to ensure each survey wave remained nationally representative despite missing data owing to nonresponse (Supplement). Participants provided informed consent via the UAS website and data collection was approved by the University of Southern California institutional review board.
In total, 7420 participants provided 42 154 survey responses (mean, 5.7 of 7 waves completed). Estimates of vaccine hesitancy declined significantly by 10.8 percentage points (95% CI, 8.9-12.7), from 46% in October 2020 to 35.2% in March 2021 (Table, Figure). Significant declines in estimates of hesitancy were observed across demographic groups and were largest among Hispanic (15.8 percentage point decrease, from 52.3% to 36.5%) and Black participants (20.9 percentage point decrease, from 63.9% to 43%). In March 2021 hesitancy was high among adults aged 18-39 years (44.1%), those without a degree (42.9%), and households earning $50 000 or less (43.7%).
Estimates of public trust in vaccination were low across all demographic groups in October 2020 (1.7 to 3.1 on a 0-6 scale) and increased significantly across all groups by March 2021 (Table). The largest increases were reported by Black and Hispanic participants (0.6-point increase) and those with a college degree (0.7-point increase).
After increased reluctance to vaccinate in 2020,1-3 this nationally representative study showed a longitudinal decline in reported vaccine hesitancy in late 2020 and early 2021. Reduced hesitancy occurred in tandem with the regulatory approval of COVID-19 vaccines and rollout of mass vaccination programs. A significant decline in vaccine hesitancy was reported across all demographic groups, especially Black and Hispanic participants. This decrease is important because COVID-19 vaccine acceptance has been particularly low among these groups, who have experienced a disproportionate burden of severe illness and death because of COVID-19.3,5,6 Declines in hesitancy were reported alongside an increase in public trust in vaccine development and the governmental approval process.
Despite these gains, in March 2021 estimates of vaccine hesitancy remained high, especially among young adults and Black and low socioeconomic status participants. Further steps are needed to build public trust, extend outreach and educational programs, and increase vaccination opportunities to ensure high levels of vaccination uptake.
The study is limited by the low UAS panel recruitment rate, participation by community-dwelling adults comfortable completing internet-based surveys in English or Spanish, and reliance on self-reported measures.
Corresponding Author: Michael Daly, PhD, Department of Psychology, Maynooth University, 1.1.7 Education House, Maynooth, Ireland (email@example.com).
Accepted for Publication: May 6, 2021.
Published Online: May 24, 2021. doi:10.1001/jama.2021.8246
Author Contributions: Dr Daly had full access to the study data and takes responsibility for the integrity of the data and accuracy of the data analysis.
Concept and design: All authors.
Acquisition, analysis, or interpretation of data: Daly.
Drafting of the manuscript: Daly, Jones.
Critical revision of the manuscript for important intellectual content: Daly, Robinson.
Statistical analysis: Daly.
Administrative, technical, or material support: Daly.
Conflict of Interest Disclosures: Dr Robinson reported receiving funding from the American Beverage Association and Unilever for projects unrelated to the present research. No other disclosures were reported.
Funding/Support: The collection of the Understanding America Study (UAS) COVID-19 tracking data was supported in part by the Bill & Melinda Gates Foundation and by grant U01AG054580 from the National Institute on Aging. Dr Robinson’s time was partly funded by the European Research Council.
Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Disclaimer: The content of this article is solely the responsibility of the authors and does not necessarily represent the official views of the University of Southern California or UAS.
Additional Contributions: The authors gratefully acknowledge the support of the European Research Council.
Additional Information: The project described in this article relies on data from survey(s) administered by the UAS, which is maintained by the Center for Economic and Social Research (CESR) at the University of Southern California.
M. International estimates of intended uptake and refusal of COVID-19 vaccines: a rapid systematic review and meta-analysis of large nationally representative samples. Vaccine
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