As the COVID-19 pandemic persists, misinformation continues to circulate widely. Journalists and public health officials struggle to debunk these false and misleading claims, an especially challenging task in the U.S., where COVID-19 has become a highly polarizing issue.

Are these efforts successful? According to a new study published in Nature Human Behaviour, fact checks can successfully reduce misperceptions about COVID-19 immediately after people read them but do not have lasting effects over time.

“Our results suggest that effectively addressing misbeliefs about COVID-19 will require repeatedly debunking false claims about the coronavirus. Otherwise, people will tend to revert back toward the level of belief that they had before,” says co-author Brendan Nyhan, the James O. Freedman Presidential Professor in the Department of Government.

“The good news is that reliable information can get a foothold,” says co-author John Carey, the associate dean for the social sciences and the John Wentworth Professor in the Social Sciences. “The next question is how to make that stick. It appears that people need regular boosters.”

During the study, respondents from the U.S., Great Britain, and Canada were asked to rate the perceived accuracy of four claims on COVID-19 that have been debunked by scientific and public health authorities: that the Chinese government created the coronavirus as a bioweapon; that a group funded by Bill Gates patented the coronavirus; that antibiotics are effective in preventing and treating COVID-19; and that the medication hydroxychloroquine is proven to cure or prevent COVID-19.

The research team then compared belief in the claims between respondents who were shown the fact checks and those who weren’t.

Regardless of when the surveys were administered, the results were the same: misperceptions about COVID-19 immediately decreased among respondents in all three countries immediately after the fact check was shown to them.

Moreover, “the fact checks were most effective among people who are more vulnerable to misperceptions of COVID-19 at baseline,” says Nyhan, including supporters of conservative leaders, those with high conspiracy predispositions, and those with low trust in health institutions.

However, these effects did not persist over time in follow-up surveys conducted in the U.S. and Great Britain.

“By comparing U.S. data on the effects of COVID-19 fact checks to that of Great Britain and Canada, we found that our results are parallel across all three countries, which suggests that the effects are not an artifact of polarization over COVID-19 in the U.S.,” says co-author Jason Reifler, a professor of politics at University of Exeter and long-time collaborator with Nyhan.

The study is the first to estimate the effects of fact checks on COVID-19 misperceptions over time and across countries. The results provide evidence that COVID-19 fact-checking can be effective but that frequent exposure is necessary for addressing misinformation during the pandemic.

Andrew Guess at Princeton University, Peter Loewen and Eric Merkley at the University of Toronto, and Joseph Phillips at the University of Kent also served as co-authors of the study.