Seroprevalence of Antibodies against Serogroup C Meningococci in England in the Postvaccination Era

Abstract

The United Kingdom introduced meningococcal serogroup C conjugate (MCC) vaccines in 1999, resulting in substantial declines in serogroup C disease and carriage. Here, we measured the age-specific prevalence of serum bactericidal antibodies (SBA) to Neisseria meningitidis serogroup C and immunoglobulin G (IgG) concentrations to serogroups A, C, W-135, and Y in 2,673 serum samples collected in England between 2000 and 2004. We compared the seroprevalence of SBA titers of >8 in the postvaccination era with results from an earlier prevaccination study conducted using the same methods. We found that the percentages of individuals with protective SBA titers were higher in 2000 to 2004 in all of the age groups targeted for MCC vaccination. In the postvaccine era, the prevalence of protective titers was high (75%) in children who had recently been offered routine immunization, but this fell to 36% more than 18 months after scheduled immunization. In the cohorts targeted in the catch-up campaign, the percentage achieving SBA titers of >8 was higher in children offered the vaccine at ages 5 to 17 years than in children offered the vaccine at ages 1 to 4 years. The geometric mean concentration (GMC) IgG for serogroup C followed a similar pattern, corresponding to the age at and time since scheduled MCC vaccination. Serogroup-specific IgG GMCs for W-135 and Y were low and showed little variation by age. Serogroup A IgG GMCs were higher, possibly reflecting exposure to cross-reacting antigens. Although the incidence of serogroup C disease remains low due to persisting herd effects, population antibody levels to serogroup C meningococci should be monitored so that potentially susceptible age groups can be identified should herd immunity wane.

Updated Postlicensure Surveillance of the Meningococcal C Conjugate Vaccine in England and Wales: Effectiveness, Validation of Serological Correlates of Protection, and Modeling Predictions of the Duration of Herd Immunity

“…Seroprevalence studies of infants and adolescents have shown that the decline in effectiveness in infants paralleled the decline in SBA, while SBA titers in adolescents showed little evidence of a decline with time, mirroring the sustained high effectiveness in this age group (27,39). Our SBA data similarly indicate a fairly rapid fall in the proportion of children with SBA titers of Ն8 within the first 12 months after primary immunization, followed by relative stability (Table 1).…”

Prevalence of Serum Bactericidal Antibody to Serogroup C Neisseria meningitidis in England a Decade after Vaccine Introduction

“…The data were first categorized into the same age-bands used in our two previous similarly designed surveys of samples taken prior to MCC introduction (in 1996 to 1999) and shortly after introduction of MCC (in 2000 to 2004) (21,23) (Fig. 1).…”

“…Field effectiveness of the initial 3-dose vaccination schedule (given at ages 2, 3, and 4 months) was shown to wane rapidly (22), and serological studies found that only 36% of children were still protected (defined as a serum bactericidal antibody [SBA] titer of Ն8, with rabbit complement) 18 months after infant vaccination (20,23). In 2006, the immunization schedule was adjusted such that MCC vaccine is now given at ages 3, 4, and 12 months.…”

Clinical and Epidemiological Differences Among Meningococcal C Conjugate Vaccine Failures and Non-Vaccinated Cases

“…Loss of vaccine effectiveness and the apparition of vaccine failures have been associated to an inadequate maintenance of circulating antibodies [7][8][9]. The effect of immaturity of the immune system in infants [10,11] to maintain the antibody levels in time has been widely studied in seroprevalence studies [9,[12][13][14][15][16][17]. In line with this, in our previous nationwide study evaluating vaccine effectiveness after 13 years since the conjugate vaccine introduction, we found 63.97% of vaccine failures in those vaccinated before the year of age (2-3 doses), 32.08% in those vaccinated between 1 and 11 years (1 dose) and 3.88% in those vaccinated between 12-19 years (1 dose) [18].…”