In a study released in the journal Pediatrics (5/09), kids who were not vaccinated against pertussis had a 23% greater chance of contracting the illness than those who were vaccinated.

Partially government funded, the Kaiser Permanente study looked at data covering 1996 – 2007 comparing infection rates between kids who received the pertussis vaccination against those who did not.

Like measles, pertussis is a highly contagious bacterial infection with up to 90% of people exposed to the bacteria, developing symptoms. Those most affected are infants under 2 months of age who lack a developed immune system and who are more likely to die from complications of pneumonia, seizures or encephalopathy.

In the past, infants have relied on “herd immunity” for protection against the illness. This means that the more children who are vaccinated against the bacteria, the less chance the bacteria has of taking hold and spreading.

The number of cases of pertussis has steadily risen from 5,000-7,000/year to over 10,400 cases in 2007 in which 10 infants died.

Adolescents and adults may contract the disease when their immunity wanes but this can be easily corrected by a booster shot given once as part of the new combination tetanus injection (Tdap).

If you are an adult who has not received a booster shot, please talk to your provider about getting one – infants and children rely on you to protect them.