How do you get skeptical parents to vaccinate their kids? Show them how scary getting the measles actually is. 

Thanks to larger numbers of parents ignoring scientific data in favor of paranoia over vaccine safety, preventable diseases like whooping cough and measles are making a major comeback in Europe and the U.S. But a new study in the journal PNAS finds that educating parents about the safety of vaccinations isn’t the answer. Scaring them about the risks of the diseases the vaccines can prevent is. 

More than 300 parents were randomly assigned to three groups in the study. One group read materials that challenged anti-vaccination views, like the idea that vaccines cause autism (a link disproved by a host of scientific studies), while another focused on the risks associated with disease like measles, mumps, and rubella, reading accounts of a mother with a measles-infected child and looking at pictures of children who were infected. A third read about another subject entirely, serving as the control. 

The people who read about the dangers of diseases like measles, mumps, and rubella and their associated complications were most likely to change their minds about the importance of vaccination, more so than the people who read about the safety of vaccines. Even the most skeptical participants were likely to be swayed by seeing pictures like an infant with rubella. 

"People who fear vaccines ultimately do care about the safety of their children, so our manipulation focuses on the safety of their children," study author Zachary Horne explains in a press statement

It makes sense. These days—thanks to vaccines—parents are more likely to have experiences with a child with autism than with the measles, so they may be more worried about their child getting autism from a vaccine (again, not a thing) than their child getting the measles from not being vaccinated. Reminding them that the measles is not like getting a bad cold may be the first step in directing their attention away from the minimal risks of vaccination toward the major risk of deadly disease.