Pertussis Immunity Wanes 5 Years After Vaccination or Infection

WESTPORT, CT (Reuters Health) Jul 10 - Booster immunization with pertussis vaccines may be necessary if adolescents and adults are to retain immunity against the infection, investigators in Italy report.

Dr. Nicola Principi, of the University of Milan, and associates evaluated 38 children at ages 5 to 6 years who had been immunized three times by age 11 months with a combined diphtheria, tetanus, tricomponent acellular pertussis, and hepatitis B vaccine (DTaP-HBV). Their immune responses were compared with those of 21 subjects who acquired pertussis during their first year of life and received only DT-HBV vaccination.

The residual immunity to pertussis was similar in the two groups, the investigators report in the July issue of Infection and Immunity. Very few children had significant serum IgG concentrations specific to all three Bordetella pertussis antigens or persistent T-cell responses 5 years after the immunizations.

The two groups tended to differ in that infection appeared to induce a type 1 response, while the vaccine appeared to induce "a type 2 skewed response." However, the quantitative differences in the amounts of cytokines produced between the groups were minimal.

Dr. Principi's team recommends that "most vaccinated or previously infected children...receive a booster in order to maintain long-term pertussis-specific humoral and cell-mediated immune response."

Infect Immun 2001;69:4516-4520.