ACIP: Second dose of Tdap not recommended

Based on recommendations from the pertussis working group, the CDC’s Advisory Committee on Immunization Practices has decided not to recommend an alternative revaccination schedule for the tetanus-diphtheria-acellular pertussis vaccine to improve the vaccine’s waning coverage of pertussis, according to presenters at the meeting.

“The working group recognizes the burden of pertussis, but the epidemiology show that the burden of pertussis decreases with age,” said Jennifer Liang, DVM, of the CDC’s Division of Bacterial Diseases. “For adolescents and adults, the majority of cases are outpatients.”

Liang also said reduction of disease burden would be limited with a second dose of Tdap.

Infants continue to have the highest risk for pertussis and are more likely to be hospitalized with the disease. In the 1990s, there was an emergence of disease among adolescents, and then in 2000 an emergence among fully vaccinated children aged 7 to 10 years. In 2012, there was again more adolescent disease.

Although the resurgence of the disease is likely due to waning protection of the acellular vaccine, data do not support a recommendation for a second Tdap in the general population. However, the working group is willing to reconsider revaccination of “at-risk” populations.

In reviews of antibody persistence with Tdap vaccination, for both diphtheria and tetanus, there were rapid rises in antibody protection immediately upon vaccination, with small declines during the first year and a plateau through to 10 years. Pertussis antigens, however, saw a substantial decline in the first 2 years since vaccination and a consistent slower decline through to 10 years.

Although a second dose was not recommended, ACIP still recommends that pregnant women receive the Tdap vaccine during each pregnancy.