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Antibody response to accelerated immunisation with diphtheria, tetanus, pertussis vaccine
1Immunisation Division, PHLS Communicable Disease Surveillance Centre, London, UK.
Insights
An accelerated diphtheria, tetanus, and pertussis (DTaP) vaccine schedule resulted in lower initial antibody concentrations. However, antibody levels in children receiving the accelerated DTaP schedule remained protective a year later.
Area of Science:
- Immunology
- Pediatrics
- Vaccinology
Background:
- A new accelerated schedule for diphtheria, tetanus, and pertussis (DTaP) vaccination was implemented in May 1990.
- Initial reports suggested lower antibody concentrations in children receiving the accelerated schedule.
Purpose of the Study:
- To assess antibody response and persistence after DTaP immunization using widely spaced versus accelerated schedules.
- To determine if the accelerated schedule impacts protective antibody levels.
Main Methods:
- Controlled study comparing antibody concentrations in children receiving accelerated (2, 3, 4 months) versus widely spaced (15, 21, 45 weeks) DTaP schedules.
- Antibody levels to diphtheria, tetanus, and Bordetella pertussis filamentous hemagglutinin (FHA) measured by solid-phase radioimmunoassay (SP-RIA).
Main Results:
- Children on the accelerated schedule had significantly lower antibody concentrations for tetanus, diphtheria, and FHA 6-8 weeks post-vaccination.
- After 12 months, antibody concentration differences narrowed, with all children maintaining protective tetanus antibody levels.
- Only a small proportion of children in both groups had diphtheria antibody concentrations below protective levels at 12 months.
Conclusions:
- The accelerated DTaP vaccination schedule is unlikely to result in a significant increase in unprotected children before preschool boosters.
- The findings support the safety and efficacy of the accelerated DTaP immunization schedule in maintaining protective immunity.
Abstract:
From May, 1990, a new schedule of immunisation against diphtheria, tetanus, and pertussis (at 2, 3, and 4 months) replaced the previous more widely spaced schedule. A report that children had lower concentrations of diphtheria and tetanus antibodies a month after an accelerated schedule led us to undertake a controlled study to assess antibody response and the persistence of antibodies a year after immunisation in children receiving vaccine according to widely spaced and accelerated schedules. Concentrations of antibodies to diphtheria and tetanus toxoids and to Bordetella pertussis filamentous haemagglutinin (FHA) were measured by solid-phase radioimmunoassay (SP-RIA). We studied 57 children who received accelerated immunisation at median ages of 11, 16, and 21 weeks and two control cohorts (total n = 82) who received vaccine at median ages of 15, 21, and 45 weeks. 6-8 weeks after the third dose the accelerated-schedule group had lower (p < 0.0001) geometric mean concentrations of antibody to tetanus (0.522 [95% CI 0.383-0.710] vs 3.43 [2.45-4.81] IU/mL), diphtheria (0.266 [0.179-0.396] vs 2.39 [0.616-3.53] IU/mL), and FHA (0.044 [0.030-0.063] vs 0.270 [0.196-0.374] units/mL) than the longer-schedule group. 12 months after the third dose the differences between the groups had narrowed (tetanus 0.197 vs 0.341 IU/mL, p = 0.29; diphtheria 0.100 vs 0.131 IU/mL, p = 0.64; FHA 0.014 vs 0.016 units/mL, p = 0.72). At that time all children had tetanus antibody concentrations above protective levels (0.01 IU/mL); only 2 of 31 in the accelerated-schedule group and 3 of 31 in the longer-schedule group had diphtheria antibody concentrations below the protective level. The use of an accelerated schedule of diphtheria, tetanus, and pertussis vaccination is unlikely to lead to an increase in the proportion of children unprotected against these diseases before the preschool booster.