Meningococcal serogroup B strain coverage of the multicomponent 4CMenB vaccine with corresponding regional distribution and clinical characteristics in England, Wales, and Northern Ireland, 2007-08 and 2014-15: a qualitative and quantitative assessment

Background The UK introduced 4CMenB-a multicomponent vaccine against serogroup B meningococcal disease-into the national infant immunisation programme in September, 2015. The Meningococcal Antigen Typing System (MATS) was used to estimate coverage by 4CMenB of invasive meningococcal group B isolates obtained during 2007-08 in England and Wales (MATS coverage). We aimed to repeat the MATS survey for invasive meningococcal group B isolates obtained during 2014-15, before 4CMenB introduction; compare strain coverage between 2007-08 and 2014-15; and investigate associations between MATS coverage, age, region, and disease outcomes. Methods Invasive serogroup B meningococcal isolates from cases in England, Wales, and Northern Ireland during 2014-15 were assayed using MATS and compared with 2007-08 data. MATS coverage was assessed by geographical region and age group. Clinical characteristics, risk factors, and outcomes were assessed according to MATS coverage for 2014-15 English cases. Findings In 2014-15, 165 of 251 (66%; 95% CI 52-80) meningococcal group B isolates were estimated by MATS to be covered by 4CMenB, compared with 391 of 535 (73%; 95% CI 57-87) in 2007-08. The proportion of MATS-positive isolates with one vaccine antigen increased from 23% (122 of 535) in 2007-08 to 31% (78 of 251) in 2014-15, whereas the proportion with more than one antigen fell from 50% (269 of 535) to 35% (87 of 251). This effect reflected changes in circulating strains, particularly ST-269 clonal complex strains. MATS coverage increased with age, varied by geographical region, and was associated with more severe disease. Interpretation In 2014-15, two-thirds of meningococcal group B isolates were predicted to be covered by 4CMenB. Temporal changes in MATS coverage underscore the need for continued monitoring of antigen expression and diversity, particularly in countries with 4CMenB programmes.