Pertussis risk much higher among unvaccinated children

Some parents, concerned that vaccines could injure their children, choose to forgo or delay childhood immunizations. One barrier to convincing on-the-fence parents of the benefits of vaccines is that the downside of refusing seems minimal. Parents who opt out often have good reason to believe that herd immunity will protect their children from harm.

But a new study finds that, at least with regard to pertussis, vaccine refusal is not risk-free. Children whose parents refused the pertussis vaccine were 23 times likelier to contract the disease than were immunized children, according to a June Pediatrics study of 156 pertussis cases drawn from the Kaiser Permanente Colorado health plan. One in 10 pertussis cases was due to vaccine refusal, the study found (link).

"We know a lot about the effectiveness and safety of vaccines, but we don't know the risks associated with not vaccinating, and a lot of parents are just unsure and concerned about this and want to know that information," said the study's lead author, Jason M. Glanz, PhD, a research investigator at the Kaiser Permanente Institute for Health Research in Colorado.

For years, vaccine skeptics have argued -- contrary to an overwhelming amount of scientific evidence -- that immunizations cause autism. From 1991 to 2004, the 20 states allowing parents to exempt children from vaccines for personal reasons saw their opt-out rates grow by 61% to 2.54%, according to an Oct. 11, 2006, Journal of the American Medical Association study (link).

That study showed that state vaccine requirements affect pertussis rates, with more opt-out friendly states having a higher prevalence of pertussis. But the new Pediatrics study appears to be the first to determine the effect of vaccine refusal for individual patients, Glanz said. He is working on further research to improve communication about vaccines among physicians and parents.

"Our objective in no way is to demonize parents who aren't vaccinating," Glanz said. "We understand that being a good parent is difficult. I have two young kids, and I understand how hard immunizing is, particularly with all the information out there -- it's so confusing. Our goal is to work on developing that trusting relationship when parents and physicians are at odds with each other. We want to work on ways to open that dialogue to communicate the risks and benefits to help parents make truly informed decisions."