Can we control all-cause meningococcal disease in Europe?
Sadarangani M., Pollard AJ.
Invasive disease caused by Neisseria meningitidis is potentially devastating, with a case-fatality rate of 5-15% and high rates of significant sequelae among survivors following septicaemia or meningitis. Capsular group C (MenC) conjugate vaccines have been highly successful in achieving control of MenC disease across Europe, and some countries have also introduced quadrivalent MenACWY conjugate vaccines to reduce disease caused by groups A, W and Y in addition. These vaccines elicit putatively protective levels of bactericidal antibodies in all age groups, induce immunological memory and reduce nasopharyngeal carriage, thereby leading to herd protection. Protein-based meningococcal vaccines based on subcapsular components, and designed primarily to target MenB disease, have recently been licensed. These vaccines are highly immunogenic in infants and adolescents, inducing bactericidal antibodies against strains expressing high levels of vaccine antigens which are identical to the variants present in the vaccines. Effectiveness of these vaccines at a population level will be determined by whether vaccine-induced antibodies provide cross-protection against variants of the vaccine antigens present on the surface of the diverse collection of circulating invasive strains. The level of serum bactericidal activity induced against strains seems also to depend on the level of expression of the vaccine antigens. The duration of protection and impact on carriage of meningococci will have a major bearing on the overall effectiveness of the programme. In September 2015 the UK became the first country to introduce 4CMenB into a national routine immunisation schedule and data on the effectiveness of this program are anticipated in the next few years.