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Disclosures: Tram reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
July 31, 2021
2 min read

Vaccine hesitancy common enough to threaten herd immunity, study finds

Disclosures: Tram reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
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Among nearly 460,000 people surveyed in the United States earlier this year, more than 10% said they would “probably not” get a COVID-19 vaccine and more than 8% said they would “definitely not,” researchers reported.

The survey showed that vaccine hesitancy remained steady as vaccine uptake increase and was high enough to threaten achieving herd immunity, the researchers said.

Tram KH, et al. Clin Infect Dis. 2021;doi:10.1093/cid/ciab633.
Tram KH, et al. Clin Infect Dis. 2021;doi:10.1093/cid/ciab633.

“We were first interested in studying the scale or magnitude of vaccine hesitancy in the United States as a way of understanding the slow uptake of vaccine during the initial rollout,” Khai Hoan Tram, MD, a fellow in the division of infectious diseases at the University of Washington, told Healio. “While access to vaccines was undoubtedly a significant barrier to uptake in many communities, we noticed that even where available, a large fraction of people still remained unvaccinated for a number of reasons.”

Sor the study, Tram and colleagues analyzed data from the U.S. Census Bureau’s Household Pulse Survey — a biweekly cross-sectional survey of U.S. households — to estimate the prevalence of and reasons for vaccine hesitancy.

“Vaccine hesitancy is not a new phenomenon, and you can look back at hesitancy with regard to other vaccines like the flu vaccine and childhood immunizations, but the drivers of COVID-19 vaccine hesitancy, specifically, appear unique in some ways and very much situated in the present-day social, political and demographic context,” Tram said.

In total, 459,235 people participated in the survey between Jan. 6 and March 29. During this time, vaccine uptake increased from 7.7% to 47% while the rate of hesitancy remained fixed.

Overall, Tram and colleagues said, vaccine hesitancy comprised a “sizable proportion” of the population, large enough to “threaten achieving herd immunity,” with 10.2% of participants reporting that they would probably not get a vaccine and 8.2% saying they definitely would not get a vaccine.

Additionally, the study showed that sociodemographic predictors for reluctance were distinct from rejection. For example, female sex and Black race were factors predicting hesitancy. These same characteristics predicted vaccine reluctance rather than rejection. Income, education and state political leaning also strongly predicted vaccine hesitancy.

“Overall, the intensity and nature of vaccine hesitancy vary between sociodemographic groups and across geographic and political lines. Different hesitant groups — for example, those who are reluctant vs. those who are rejecting the vaccine — need segmented public health strategies and targeted approaches to promote vaccine uptake,” Tram said. “Vaccine efficacy is not sufficient for vaccine uptake. Implementation of vaccine rollout needs to account for a variety of perspectives and attitudes. There's a lot of work to be done.”