Celebrities are endorsing COVID vaccines. Does it help?

There is some evidence that celebrity endorsements of a given medical behavior can have concrete results. After Katie Couric had a colonoscopy live on the “Today” show in 2000, for example, the number of colorectal screenings in the United States soared for about nine months. And in Indonesia, researchers found in a pre-coronavirus experiment that when 46 celebrities agreed to tweet or retweet pro-immunization messages, their posts were more popular than similar ones from noncelebrities. That was especially true when the celebrities delivered the message in their own voices, rather than citing someone else, researchers found. “Their voice matters,” said Vivi Alatas, an economist in Indonesia and a co-author of that study. “It’s not just their ability to reach followers.” For the most part, though, the science linking celebrity endorsements to behavioral change is tenuous.