According to a study completed by Kaiser Permanente Institute for Health Research, children who aren't vaccinated are 23 times more likely to get whooping cough, also called pertussis.The study is scheduled to be published in the June 2009 Pediatrics.

Whooping cough is highly contagious and can cause a child to have an intense cough that can last several months, which can be so severe that it can cause damage to the ribs.

Since delayed vaccinations (and skipping them altogether) are becoming increasingly popular parenting choices, doctors are concerned that this is just the beginning, fearing that more previously eliminated social diseases will resurface.

"This study helps dispel one of the commonly held beliefs among vaccine-refusing parents: that their children are not at risk for vaccine preventable diseases," says Dr. Jason Glanz, the lead scientist in the study. "It also 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."