Seroprevalence of meningococcal serogroup C bactericidal antibodies in the Portuguese population, a decade after vaccine introduction in the National Immunisation Programme

Background The incidence of invasive meningococcal disease due to serogroup C (MenC) decreased in Portugal since the introduction conjugate vaccine (MCC) free market 2001 and National Immunisation Plan 2006. Considering potential waning antibody response reported literature, different vaccination schemes that were used our country over past decade, Neisseria meningitidis continues circulate, Portuguese population may currently be at increased risk infection. In absence national data, we evaluated seroprotection level against MenC, order identify protected fraction ponder on necessity a booster dose MCC vaccine. Methods We measured serum bactericidal levels MenC representative sample (n = 1500) aged 2–64 years who participated 2015/2016 Serological Survey. Results A total 31.1% (466/1500, 95%CI: 29–33%) individuals studied MenC. geometric mean titre was 6.5. proportion seroprotected particularly low children 2–4 (<16%) received single 12 months age (vaccination strategy 2012). higher (44.7% 53.5%) adolescent young adults (15–24 age), resulting from during catch-up campaign 5–15 age. highest protection rates observed when administered adolescence. Conclusion small seroprotected, combined with already known effect time, indicate will become progressively more exposed Taking consideration results, recommend change current introduce