Whooping Cough, Pertussis Vaccine TDap can Wear Off in Teens, Young Adult: Study

Will this be a cause of panic for mothers everywhere?

According to a new study published Friday in the journal Pediatrics, the booster vaccine that is formulated to protect teenagers against whooping cough may wear off over time.

Designed to protect kids against pertussis, or whooping cough, tetanus and diphtheria, the Tdap booster was found to have only protected about 69% of adolescents against whooping cough in the first year after the booster was administered. However, the protection dropped to 57% in the second year, then to 25% and 9% in the succeeding years, according to a report by CNN.

To come up with these results, the researchers studied pertussis infections in about 280,000 10-year olds from 2009 until 2015. The children were all reported to have received Tdap by the time they were 11 or 12, as California mandates the booster for seventh graders.

"It provides moderate protection during the first year but years two and three after vaccination, there is not that much protection left," says Dr. Nicola P. Klein, lead author and co-director of the Kaiser Permanente Vaccine Study Center in Northern California. 

 "The results in this study raise serious questions regarding the benefits of routinely administering a single dose of Tdap to every adolescent at age 11 or 12," Dr. Klein adds in a statement to Live Science.

She furthers that, because Tdap provides protection in a short-term more successfully, the booster may help prevent pertussis more effectively if it is administered to adolescents in preparation for a local outbreak rather than on a routine basis.

Live Science reports that, in the 1990s, the United States government switched from whole-cell pertussis (DTwP) vaccine to the acellular pertussis (DTaP) vaccine due to concerns about the side effects of the whole-cell vaccine. Although the vaccine was effective in preventing whooping cough, it was linked with very high fevers, according to Dr. Klein.

As of today, the DTaP vaccine is administered during childhood in five doses: at ages 2 months, 4 months, 6 months, 12 to 18 months, and 4 to 6 years. In spite of this regular vaccination, the United States as well as other developed countries have experienced an increase in cases of pertussis since they changed the vaccines to DTaP.

In 2006, health authorities have began recommending vaccines with the acellular pertussis Tdap vaccine be given 11 or 12 year olds. It was found that these children were the most likely to get sick with pertussis just before they were scheduled to get their booster shots.