Acellular vaccines containing reduced quantities of pertussis antigens as a booster in adolescents

Objective. To evaluate the immunogenicity and reactogenicity of an acellular pertussis vaccine (pa) either formulated with diphtheria and tetanus toxoids (dTpa) or administered consecutively with a licensed tetanus and diphtheria vaccine (Td) as a 5th dose in adolescents. Methods. A total of 510 healthy children 10 to 13 years of age were assigned randomly, using a single-blind design, to receive either the dTpa vaccine or the Td vaccine with the pa vaccine 1 month later. The quantities of 3 pertussis antigens (pertussis toxin, filamentous hemagglutinin, and pertactin) in the dTpa and the pa vaccines were one third of those of the Infanrix vaccine (Smith-Kline Beecham Biologicals, Rixensart, Beligium) licensed for use in infants. For enzyme-linked immunosorbent assay measurement of serum immunoglobulin G antibodies and proliferation assay of peripheral blood mononuclear cells, blood samples were obtained before and 1 month after immunization. Local and systemic reactions were recorded on diary cards for 15 days after immunization. Results. After immunization with dTpa or pa, significant and comparable rises in geometric mean values of antibodies (12- to 46-fold) and proliferations (8- to 18-fold) to each of the pertussis antigens were noted. After immunization with dTpa or Td, significant rises in geometric mean values of antidiphtheria and antitetanus antibodies (35- to 76-fold) were noted, and all subjects had values of these antibodies greater than or equal to.1 international units/mL. The dTpa and pa vaccines were at least as well tolerated as the licensed Td vaccine. Conclusions. Booster immunization of adolescents with an acellular vaccine containing reduced quantities of pertussis antigens in addition to diphtheria and tetanus toxoids induces good responses in both arms of the immune system without an increase in adverse reactions.