Pertussis, also known as whooping cough, is rising sharply and a new study suggests that a contributing cause may be that the vaccine now used loses effectiveness over time. Which means it may be time for you to get a booster.
The old vaccine, introduced in the late 1940s, dramatically reduced pertussis infections but was often associated with redness, swelling, pain at the injection site, and, in a few cases, serious complications. The current vaccine, which is called DTaP and also vaccinates against diphtheria and tetanus, was introduced in 1992 to reduce those risks.
Infants are most likely to be hospitalized and die from pertussis, but there's also been a sharp increase among school-aged children and even adults, according to the new study, which was published this week in the Journal of the American Medical Association. According to the study, California had its largest pertussis epidemic in 60 years in 2010, with more than 9,000 reported cases and 10 infant deaths. Researchers studied the vaccine records of children ages 4 to 10 and found that the longer the time since the final dose of the vaccine, the greater the risk of infection. That suggests that the vaccine loses effectiveness over time.
Despite whooping cough's recent resurgence, cases are still far below what they were in the pre-vaccine era. Another finding from the JAMA study: unvaccinated children were nine times more likely to contract pertussis than were their immunized peers.
Bottom line: Researchers may eventually recommend a different vaccination schedule or develop a longer lasting vaccine. But for now, the DTaP vaccine offers substantial protection against whooping cough. The vaccine is actually a series of five shots, all of which must be completed in order for it to be most protective. Children should receive doses one through three before their first birthday, dose four between by 18 months old, and dose five between ages 4 and 6 . An adolescent booster, Tdap, should be administered at age 11. Pregnant women should also get a shot, as should people 65 and older who are in contact with infants. For details, see our advice on vaccines for children and adults. And see the CDC's pertussis website.