Evaluation of strain coverage of the multicomponent meningococcal serogroup B vaccine (4CMenB) administered in infants according to different immunisation schedules

Abstract

The 4-component vaccine 4CMenB, developed against invasive disease caused by meningococcal serogroup B, is approved for use in infants in several countries worldwide. 4CMenB is mostly used as 3 + 1 schedule, except for the UK, where a 2 + 1 schedule is used, and where the vaccine showed an effectiveness of 82.9%. Here we compared the coverage of two 4CMenB vaccination schedules (3 + 1 [2.5, 3.5, 5, 11 months] versus 2 + 1 [3.5, 5, 11 months of age]) against 40 serogroup B strains, representative of epidemiologically-relevant isolates circulating in England and Wales in 2007-2008, using sera from a previous phase 3b clinical trial. The strains were tested using hSBA on pooled sera of infants, collected at one month post-primary and booster vaccination. 4CMenB coverage was defined as the percentage of strains with positive killing (hSBA titres ≥ 4 after immunisation and negative baseline hSBA titres < 2). Coverage of 4CMenB was 40.0% (95% confidence interval [CI]: 24.9-56.7) and 87.5% (95%CI: 73.2-95.8) at one month post-primary and booster vaccination, respectively, regardless of immunisation schedule. Using a more conservative threshold (post-immunisation hSBA titres ≥ 8; baseline ≤ 2), at one month post-booster dose, strain coverages were 80% (3 + 1) and 70% (2 + 1). We used a linear regression model to assess correlation between post-immunisation hSBA data for each strain in the two groups; Pearson's correlation coefficients were 0.93 and 0.99 at one month post-primary and booster vaccination. Overall, there is no evidence for a difference in strain coverage when 4CMenB is administered according to a 3 + 1 or 2 + 1 infant vaccination schedule.

Keywords: 4CMenB vaccine; infant immunisation schedule; meningococcal serogroup B; pooled sera; serum bactericidal antibody assay; strain coverage.

Figure 1.

Focus on the patient section.

Figure 2.

Study interventions and number of infants from whom sera was collected, by time point. N, number of infants with tested serum samples. Note: The test tube and syringe symbols indicate time points of blood draw and vaccination with 4CMenB, respectively.

Figure 3.

hSBA titres against individual serogroup B strains at one month post-primary (A) and booster (B) vaccination. hSBA, serum bactericidal antibody assay with human complement. Note: Horizontal lines represent the median value for hSBA titres in each group.

Figure 4.

Distribution of hSBA titres against serogroup B strains at one month post-primary (A) and booster (B) vaccination. hSBA, serum bactericidal antibody assay with human complement.

Figure 5.

Correlation between hSBA titres of pooled sera in each group at one month post-primary (A) and booster vaccination (B). hSBA, serum bactericidal antibody assay with human complement.