Vaccine Refusals Fueled California’s Whooping Cough Epidemic When the whooping cough vacci

Vaccine Refusals Fueled California’s Whooping Cough Epidemic

When the whooping cough vaccine was invented in the 1940s, doctors thought they had finally licked the illness, which is especially dangerous for babies. But then it came roaring back.

In 2010, a whooping cough outbreak in California sickened 9,120 people, more than in any year since 1947. Ten infants died; babies are too young to be vaccinated.

Public health officials suspected that the increased numbers of parents who refused to vaccinate their children played a role, but they couldn’t be sure.

Vaccine refusal was indeed a factor, researchers now say. They compared the location and number of whooping cough, or pertussis, cases in that outbreak with the personal belief exemptions filed by parents who chose not to vaccinate for reasons other than a child’s health. (Some children with compromised immune systems aren’t able to be vaccinated.)

Pertussis is very contagious, spreading quickly through a community. So the researchers had to map not only the location of outbreak clusters, but also when they appeared.

They found that people who lived in areas with high rates of personal belief exemptions were 2 ½ times more likely to live in a place with lots of pertussis cases. “The exemptions clustered spatially and were associated with clusters of cases,” Jessica Atwell, a graduate student at Johns Hopkins Bloomberg School of Public Health and lead author on the study, told Shots. It was published online in the journal Pediatrics.

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The photograph above show Bordetella pertussis, the bacterium that causes whooping cough, under the electron microscope. Image by Sanofi Pasteur/Flickr.com.