Pertussis more common in children as parents refuse vaccines

Children who are not vaccinated against pertussis are 23 times more likely to get the disease compared to fully immunized children, according to a study led by a vaccine research team at Kaiser Permanente Colorado’s Institute for Health Research and funded by the National Institute of Allergy and Infectious Diseases.

Researchers reviewed the electronic health records of children between the ages of 2 months and 18 years who were enrolled in Kaiser Permanente Colorado between 1996 and 2007. The researchers confirmed which children had pertussis infections, then verified whether parents had refused some or all vaccines for their children.

The researchers found 156 laboratory-confirmed pertussis cases that met the study’s criteria. They compared these cases to four times as many children of the same age and gender who were not infected with pertussis. Based on this analysis, the researchers noted that children of vaccine refusers were 23 times more likely to be infected with whooping cough than vaccinated children.

“The study shows that the decision to refuse immunizations could have important ramifications for the health of the entire community. Based on our analysis, we found that one in 10 additional whooping cough infections could have been prevented by immunization,” study lead author Jason Glanz, PhD, a senior scientist at Kaiser Permanente’s Institute for Health Research said in a press release.

While most families vaccinate their children, leading to dramatic reductions in several serious childhood illnesses, the number of parents refusing immunizations appears to be increasing in the United States, researchers noted. The study could not determine from the information available why parents elected to refuse vaccines.

The study will appear in the June 2009 issue of Pediatrics.