Study: Whooping Cough Vaccine Immunity Wanes

A new study has found that immunity from the DTaP  (Diptheria, Tetanus and Pertussis) vaccine can fade in the years between the final shot in the childhood series and the booster administered in adolescence. This gap makes 7- to 10-year-olds particularly vulnerable to contracting pertussis, or whooping cough, according to researchers for the Centers for Disease Control & Prevention.

The study, published in Pediatrics, looked at the immunization records in two states and compared them to pertussis case data. Researchers saw an uptick of whooping cough cases in this age group in recent years despite high vaccine rates. The risk of pertussis seems to increase with each year after the final dose in the 5-shot series, usually administered between ages 4 to 6.

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Researchers think the decreased protection may have to do with a change made to the vaccine in 1997, says Sara Tartof, MPH, lead researcher for the study. That year, the switch was made from a whole-cell vaccine, which was associated with more averse reactions like swollen limbs, to a better-tolerated acellular version, which researchers now think may be not as effective. This is the first time researchers have been able to study this age cohort since the change was made.

What can parents do to protect their big kids from whooping cough? The vaccine still offers the best protection, says Dr. Tartof. “We have seen that if a child is vaccinated, the disease is much milder, so it’s still the best protection we can offer,” she told Parenting.com. Also, parents, grandparents, and caregivers should ask their doctor about a booster to provide community immunity for kids.

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Do you worry about your child contracting whooping cough? Leave a comment.