Evaluation of Haemophilus influenzae type b conjugate vaccine (meningococcal protein conjugate) in Canadian infants.

OBJECTIVE: To assess adverse effects and immune responses with a three-dose series of Haemophilus influenzae type b meningococcal protein conjugate (PedvaxHIB or Hib.OMP) vaccine, including any immunological response alterations from concurrent administration with routine vaccines for infants. DESIGN: Randomized, controlled trial with treatment group crossover for dose 3. SETTING: Two public health units near Vancouver. PARTICIPANTS: One hundred and ten healthy infants eight to 14 weeks old were enrolled; 105 completed the study (95%). INTERVENTIONS: All participants received two doses of diphtheria-pertussis-tetanus (dpt) vaccine (at two and four months of age) and one dose of measles-mumps-rubella (mmr) vaccine at 12 months. In each instance, Hib.OMP was given either concurrently in another limb or after a delay of two weeks (after dpt) or four weeks (after mmr). MAIN OUTCOME MEASURES: Adverse effects, particularly fever and local erythema, were monitored by parents for 72 h after each dose of Hib.OMP vaccine. Five blood samples were taken at prescribed intervals to assess responses to each dose of Hib.OMP and to selected other vaccine antigens. MAIN RESULTS: Follow-up was obtained after all 322 doses of Hib.OMP. Local adverse effects were infrequent and mild: 13% had redness, 17% tenderness. Systemic effects in those given Hib.OMP alone included fever in 8%, irritability in 29%. Anti-polyribose-ribitol phosphate (prp) responses to Hib.OMP were not impaired by coadministration with dpt or mmr vaccines, nor were tetanus or diphtheria antitoxin levels or rubella or measles response rates affected. After two doses of Hib.OMP, 92% were seropositive and 64% had greater than 1.0 µg/mL of anti-prp. After three doses, 100% were seropositive and 82% exceeded 1.0 µg/mL. CONCLUSION: Hib.OMP vaccine was well tolerated, immunogenic and compatible with vaccines routinely given to infants in Canada.

The role of secondary vaccine failures in measles outbreaks.

An outbreak of measles in 1985-86 in a community where measles vaccine trials had been carried out from 1974-76 allowed the assessment of the role of secondary vaccine failures in previously immunized children. A total of 188 children from the vaccine trial were followed. Of these, 175 seroconverted initially while 13 (6 per cent) required re-immunization (primary failure). A total of 13 cases of measles, eight of which were laboratory and/or physician-confirmed, were reported in this cohort. Of these, nine cases occurred in the 175 subjects who had hemagglutination inhibition test (HI) and neutralizing antibody responses following the initial immunization. These nine cases represent secondary vaccine failures. An additional four cases occurred in the 13 subjects with primary vaccine failure. We conclude that secondary vaccine failures occur and that while primary failures account for most cases, secondary vaccine failures contribute to the occurrence of measles cases in an epidemic. A booster dose of measles vaccine may be necessary to reduce susceptibility to a sufficiently low level to allow the goal of measles elimination to be achieved.

Survey of bereaved parents.

A retrospective study in Vancouver was designed to evaluate parents' perceptions of support received after the death of a child up to 5 years old. The families were contacted with the help of health care professionals and the news media. A standardized questionnaire was used in a personal interview or occasionally by mail. The contact with health care professionals after the child's death was frequently considered by the 61 families not to have been helpful: 80% of the families judged the information or counselling they had received to be inadequate, and over 50% had received none; many listed comments and behaviour that they considered harmful. The families desired both full medical information and grief support; what forms such support could take are suggested.