People in Republican-voting states were more likely to report adverse events after receiving a Covid-19 vaccination than people living in Democratic-leaning states, a new analysis finds, suggesting that how people view their post-vaccine side effects or decide whether to report them may be shaped by their political views.

The cross-sectional study, published Friday in JAMA Network Open, looked at more than 620,000 entries in the Vaccine Adverse Event Reporting System from 2020 through 2022 and found that a 10% increase in ballots cast for a Republican in the last presidential election was associated with a 5% increase in the odds that an adverse event after Covid vaccination would be reported, a 25% increase in odds that a severe adverse event would be reported, and a 21% increase in the odds that any reported adverse event would be severe.

“It’s all part of this incredible polarization that’s politically charged,” Eric Topol, founder and director of the Scripps Research Translational Institute, told STAT. He was not involved in the study. “The fact that they’re reporting a significant increase in states that are Republican is just consistent with everything we’ve seen in the pandemic.”