More than a third of people nationwide report they are either unlikely or at least hesitant to get a COVID-19 vaccine when it becomes available, a new study shows.

The results, from public polling of more than 800 English-speaking adults nationwide, appear in the journal Vaccine.

“Our research indicates that vaccine uptake will be suboptimal… with 14.8% of respondents being unlikely to get vaccinated and another 23% unsure,” says lead author Jeanette B. Ruiz, assistant professor of teaching communication at the University of California, Davis.

The top four reasons given for vaccination hesitancy included concerns about vaccine side effects, worries about allergic responses to the vaccine, doubts about vaccine effectiveness, and a preference for developing immunity through infection.

Demographic predictors of planning to receive COVID-19 vaccine included having an income of $120,000 or higher, or being a Democrat (in comparison to the reference category Republican). The members of three political groups—Democrat, Republican, or Independent—did not differ in their reported vaccine knowledge, however.

“Even though vaccination remains one of the most effective public health initiatives, some still doubt the efficacy and safety of vaccines. Unfortunately, the seemingly rushed process of the COVID-19 vaccine may have further fueled these doubts.”

Read the full article about vaccine hesitancy by Karen Nikos at Futurity.