Luis Barreto

BACKGROUND: Pertussis is increasingly recognized as an important cause of cough illness in adolescents and adults. PURPOSE: To evaluate the safety and antibody response to a single dose of an adult formulation of a five component (pertussis toxoid, filamentous hemagglutinin, pertactin, fimbriae 2 and 3) acellular pertussis vaccine (aP) combined with diphtheria and tetanus toxoids (TdaP) and inactivated poliovirus vaccine (TdaP-IPV) in adolescents and adults and to assess the response to a second dose of the acellular pertussis vaccine in a subset of the adults. POPULATION AND SETTING: The study addressed 1207 healthy participants (736 adults and 466 adolescents) recruited in five Canadian communities. STUDY DESIGN: In a randomized, observer-blind, controlled clinical trial, adult participants received Td followed at a separate visit by aP, TdaP followed by IPV or TdaP-IPV; adolescents received Td-IPV followed at a separate visit by aP or TdaP-IPV. A subgroup of adults was given a booster of aP 1 month after TdaP. OUTCOME MEASURES: Antibody titers measured before and 1 month after each immunization; adverse events enumerated at 24 h, 72 h and 8 to 10 days. RESULTS: The aP vaccine given by itself was associated with adverse events less frequently than were Td, Td-IPV, TdaP or TdaP-IPV vaccines, but reaction rates did not differ significantly among the latter products. The antibody response against Bordetella pertussis antigens was vigorous in all groups, although adults given the TdaP-IPV vaccine had lower antibody titers against filamentous hemagglutinin, pertactin, diphtheria and tetanus antibodies than those given TdaP vaccine. Similarly adolescents given TdaP-IPV had lower antibody titers against pertussis toxin, filamentous hemagglutinin, fimbriae and agglutinins than those given Td-IPV and aP alone. A second dose of acellular pertussis vaccine was not associated with increased adverse events in adults but elicited increased antibody titers over that achieved by a single dose only against pertussis toxin. CONCLUSIONS: This adult formulation five component aP vaccine given as TdaP-IPV is safe and immunogenic in adolescents and adults and is a candidate vaccine for adolescent and adult immunization programs.

During outbreaks of measles, measles vaccine is recommended for infants considered to be at risk who are 6 months of age and older. In a prospective trial the serologic response to early measles immunization has been evaluated in 125 infants given monovalent measles vaccine at 6 to 8.5 months of age and measles-mumps-rubella at 15 months. The response to vaccination was measured by plaque reduction neutralization (PRN) assay and enzyme immunoassay. Infants were grouped by the mother's immunization history: natural immunity (n = 60, Group 1); killed followed by live, further attenuated vaccine (n = 22, Group 2); and live, further attenuated vaccine only (n = 43, Group 3). The prevaccination geometric mean titer (GMT) by PRN for Group 1 (GMT = 69) was significantly higher than that of Group 2 (GMT = 18) or 3 (GMT = 13). Seroconversion (4-fold increase in PRN titer) rates after monovalent vaccine were 31, 71 and 76% for Groups 1, 2 and 3, respectively. Seroconversion percentages were higher when measured 6 to 8 weeks after vaccination compared with 4 to 5 weeks. After measles-mumps-rubella > or = 97% of all infants had PRN titers > 120 and were measles IgG-positive by enzyme immunoassay. These data show that as demographics shift to a well-vaccinated maternal population and susceptibility in younger infants, measles vaccination before the currently recommended age will be effective.