Meningococcal serogroup C conjugate (MCC) vaccines were licensed in the UK more than 10 years ago based on correlates of protection that had previously been established for serogroup C containing polysaccharide vaccines using the serum bactericidal antibody (SBA) assay. These correlates of protection were subsequently validated against post licensure estimates of observed vaccine effectiveness up to 7-9 months after the administration of MCC vaccine. Vaccine effectiveness was however shown to fall significantly more than one year after the administration of a 3 dose course in infancy. Despite this finding the marked impact on serogroup C disease has been sustained with the lowest ever recorded incidence (0.02 per 100,000 population) in 2008/09, mainly due to the indirect herd immunity effect of the vaccine in reducing carriage. Updated estimates of vaccine effectiveness to 30 June 2009 confirmed high short term protection after vaccination in infancy at 97% (95% CI, 91% to 99%) falling to 68% (95% CI, -63 to 90%) more than a year after vaccination. Observed vaccine effectiveness more than 12 months post vaccination was consistent with measured declining SBA levels but confidence intervals were imprecise and vaccine effectiveness estimates were consistent with SBAs of 1:4 or 1:8 as correlates of long term protection after a primary course in infants. Modelling suggested protection against carriage persists for at least 3 years and predicted stabilisation of serogroup C disease levels at low levels (fewer than 50 cases per year) up to 2015/2016.
|Translated title of the contribution||Updated post-licensure surveillance of meningococcal C conjugate vaccine in England and Wales: effectiveness, validation of serological correlate of protection and modelling predictions of the duration of herd immunity|
|Pages (from-to)||200 - 208|
|Journal||Clinical and Vaccine Immunology|
|Publication status||Published - Mar 2010|