A viral claim about chickenpox vaccines is spreading. Here’s what the evidence says.

A resurfaced video claims chickenpox vaccination fuels shingles outbreaks. Studies show shingles is less common among vaccinated kids.

Most people have a virus hiding in their cells. It’s probably been there for years, and it could reactivate anytime. This virus, varicella-zoster, causes both chickenpox and shingles, a painful rash infection.

Fortunately, vaccines protect against these diseases. But can a vaccine against one infection cause the other?

In a 2023 video clip that recently recirculated on social media, anti-vaccine activist Robert F. Kennedy Jr. said that a California study found that widespread chickenpox vaccination stops chickenpox but later “causes shingles epidemics.”

It was not immediately clear what study Kennedy, now the Trump administration’s Health and Human Services secretary,  was referring to, and we didn’t hear back from his Health and Human Services Department. But current available research doesn’t show that widespread chickenpox vaccination efforts increased shingles cases in the U.S.