A comparative study of PENTA vaccine booster doses given at 12, 15, or 18 months of age
D W Scheifele1, R Guasparini, P Lavigne
1Vaccine Evaluation Center, BC's Children's Hospital, Vancouver, Canada.
Insights
Booster immunization with Haemophilus influenzae type b conjugate vaccines (PRP-T) between 12 and 18 months shows stable antibody levels. While 12-month boosters have milder side effects, 18-month boosters elicit stronger immune responses to most antigens.
Area of Science:
- Pediatric immunology
- Vaccinology
- Infectious disease prevention
Background:
- Booster doses of Haemophilus influenzae type b conjugate vaccines are typically given between 12-18 months.
- The optimal timing for these boosters to maximize immune response and minimize adverse effects is not fully established.
Purpose of the Study:
- To evaluate the impact of booster immunization timing (12, 15, or 18 months) on pre-immunization antibody levels and subsequent immune responses to a PRP-T conjugate vaccine.
- To assess local injection site reactions associated with different booster timings.
Main Methods:
- A randomized controlled trial involving 253 healthy children previously immunized with a PENTA vaccine (DPT-IPV/PRP-T).
- Children received their PENTA booster concurrently with MMR vaccine at 12, 15, or 18 months.
- Antibody levels (anti-PRP and others) and adverse events were measured before and 4 weeks after booster vaccination.
Main Results:
- Pre-booster anti-PRP antibody levels were comparable across all age groups.
- Post-booster anti-PRP geometric mean concentrations (GMCs) were significantly higher in older children (18 months) compared to younger ones (12 months).
- Booster responses to other vaccine antigens were strongest when administered at 18 months; however, 12-month boosters showed less injection site morbidity.
Conclusions:
- Anti-PRP antibody levels remain stable in children aged 12-18 months who have previously received PRP-T vaccination.
- While 18-month boosters yield superior immune responses to most antigens, 12-month boosters are associated with reduced local reactions.
- All tested ages demonstrated satisfactory immune responses, suggesting flexibility in booster timing within this window.
Abstract:
For infants immunized with Haemophilus influenzae type b conjugate vaccines, booster immunization is usually recommended in the second year of life, typically between 12 and 18 months. This study assessed the effect of age at booster immunization on pre-immunization antibody trough levels and on subsequent responses, for a PRP-T conjugate vaccine. Subjects were healthy children who had received PENTA vaccine (DPT-IPV/PRP-T combination) as infants. They were enrolled and given measles-mumps-rubella vaccine (MMR) at 12 months of age, then randomly assigned to receive PENTA vaccine concurrently with MMR or at 15 or 18 months of age. Parents were asked to note any adverse effects after PENTA vaccination. Blood samples were obtained prior to PENTA vaccination and 4 weeks later, and tested for antibodies to each antigen. In total 253 children received PENTA vaccine: 86 at 12 months, 85 at 15 months and 82 at 18 months. Injection site redness and swelling were least extensive in the youngest group (p < 0.001) but their rates of occurrence did not differ with age. Anti-PRP levels were similar in each age group prior to immunization; post-booster geometric mean concentrations (GMCs) ranged from 13.0 microg/ml in the youngest to 33.9 microg/ml in the oldest subjects (p < 0.0001). For each of the other antigens examined, booster responses were strongest at 18 months. We conclude that anti-PRP levels are stable between 12 and 18 months in children previously given PRP-T vaccine. PENTA boosters given at 12 months appear to cause milder injection site morbidity whereas those given at 18 months result in stronger responses to virtually every constituent antigen, although each age group responded satisfactorily.
