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A High-throughput Shigella-specific Bactericidal Assay
Published on: February 27, 2019
Evaluation of Meningococcal Serogroup C Bactericidal Antibodies after Primary Vaccination: A Multicentre Study, Italy
Arianna Neri1, Massimo Fabiani1, Anna Maria Barbui2
1Department Infectious Diseases, Istituto Superiore di Sanità, 00161 Rome, Italy.
Insights
Antibody levels against meningococcal serogroup C decrease annually after vaccination in children. Protection wanes significantly within five years, highlighting the need for booster strategies.
Area of Science:
- Immunology
- Vaccinology
- Pediatrics
Background:
- Serogroup C Neisseria meningitidis infections pose a significant risk to children.
- Meningococcal conjugate vaccines are crucial for preventing invasive meningococcal disease.
Purpose of the Study:
- To evaluate the persistence of bactericidal antibodies against meningococcal serogroup C over time in vaccinated children.
- To assess the impact of different meningococcal vaccines on long-term antibody levels.
Main Methods:
- Analysis of 348 serum samples from children vaccinated against meningococcal serogroup C.
- Measurement of antibody titers using a serum bactericidal antibody (SBA) assay with rabbit complement (rSBA).
- Evaluation of antibody levels at various time points post-vaccination, up to five years.
Main Results:
- Bactericidal antibody titers declined significantly by 23% annually after vaccination.
- Proportion of children with protective antibodies decreased from 67.7% at one year to 36.7% at five years post-vaccination with the MCC vaccine.
- High antibody levels (90.6%) were observed in children vaccinated with the tetravalent meningococcal serogroup ACWY vaccine after seven months.
Conclusions:
- Primary vaccination with meningococcal serogroup C conjugate vaccines leads to a decline in protective antibody levels over time.
- The tetravalent meningococcal serogroup ACWY vaccine appears to induce more durable antibody responses against serogroup C.
- Findings suggest potential waning immunity and the need for further evaluation of booster strategies.
Abstract:
Here, we evaluated over time in different cohorts of children vaccinated against serogroup C Neisseria meningitidis, the presence of antibodies with neutralizing activity. A total of 348 sera samples of enrolled children by year since vaccination (<1 year- up to 5 years), starting from February 2016 to December 2017, were collected in three collaborating centers. Meningococcal serogroup C (MenC) antibody titers were measured with a serum bactericidal antibody (SBA) assay using rabbit complement (rSBA) following standard operating procedures. The cut-off of rSBA titer ≥ 8 is considered the correlate of protection. We observed a significantly declining of bactericidal rSBA titers by 23% every year, for every 1-year from vaccination (Adjusted PR = 0.77, 95% CI: 0.71−0.84). The proportions of children with bactericidal antibodies, immunized with the meningococcal serogroup C conjugate (MCC) vaccine, declined from 67.7% (95% CI: 48.6−83.3%) one year after vaccination, to 36.7% (95% CI: 19.9−56.1%) five years after vaccination (chi-square for linear trend, p < 0.001). Children vaccinated with the tetravalent meningococcal serogroup ACWY vaccine resulted in a high proportion of bactericidal rSBA MenC titer ≥ 1:8 (90.6%, 95% CI: 79.3−96.9%) after a mean time of seven months. Overall, the results provide some evidences on the evaluation of meningococcal serogroup C bactericidal antibodies after primary vaccination.
