Immunologic memory 5 years after meningococcal A/C conjugate vaccination in infancy

Area of Science:

• Immunology
• Vaccinology
• Pediatrics

Background:

• Infant vaccination with meningococcal conjugate vaccines (MenAC) is crucial for long-term protection against meningococcal disease.
• Assessing the durability of immune memory following infant MenAC vaccination is essential for public health strategies.

Purpose of the Study:

• To evaluate antibody levels and immunologic memory in 5-year-old children previously vaccinated with MenAC in infancy.
• To determine the impact of different booster vaccinations at age 2 on subsequent immune responses at age 5.

Main Methods:

• Children who received infant MenAC were randomized at age 2 to receive a booster of MenAC, meningococcal A/C polysaccharide (MPS), or inactivated polio vaccine (IPV).
• All groups, along with unvaccinated controls, received an MPS revaccination at age 5.
• Serum bactericidal antibody titers against serogroup C were measured before and 10 days after revaccination.

Main Results:

• Before revaccination at age 5, antibody titers were higher in the MenAC and MPS groups compared to controls; IPV group titers were similar to controls.
• Ten days post-revaccination, the MenAC and IPV groups showed significantly higher serogroup C antibody titers than the MPS and control groups.
• Immunologic memory was sustained for at least 5 years, but prior MPS challenge at age 2 appeared to interfere with the subsequent memory response.

Conclusions:

• Infant meningococcal conjugate vaccination provides sustained immunologic memory for at least 5 years.
• Meningococcal A/C polysaccharide challenge at age 2 may negatively impact the immune response to subsequent MPS revaccination at age 5.