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.
Meningococcal serogroup C conjugate (MCC) vaccines were licensed in the United Kingdom more than 10 years ago based on correlates of protection that had previously been established for serogroup C-containing polysaccharide vaccines by using the serum bactericidal antibody (SBA) assay. These correlates of protection were subsequently validated against postlicensure estimates of observed vaccine effectiveness up to 7 to 9 months after the administration of the MCC vaccine. Vaccine effectiveness was, however, shown to fall significantly more than 1 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 recorded incidence (0.02 case per 100,000 population) in the 2008-2009 epidemiological year, mainly due to the indirect herd immunity effect of the vaccine in reducing carriage. Updated estimates of vaccine effectiveness through 30 June 2009 confirmed high short-term protection after vaccination in infancy, at 97% (95% confidence interval [CI], 91% to 99%), falling to 68% (95% CI, -63% to 90%) more than a year after vaccination. The observed vaccine effectiveness more than 12 months postvaccination was consistent with measured declining SBA levels, but confidence intervals were imprecise; vaccine effectiveness estimates were consistent with SBA titers of 1:4 or 1:8 as correlates of long-term protection after a primary course in infants. Modeling suggested that protection against carriage persists for at least 3 years and predicted the stabilization of serogroup C disease at low levels (fewer than 50 cases per year) up to 2015-2016.
Campbell
Helen
H
Immunisation, Hepatitis and Blood Safety Department, Health Protection Agency Centre for Infections, 61 Colindale Avenue, London NW9 5EQ, UK. helen.cambell@hpa.org.uk
Andrews
Nick
N
Borrow
Ray
R
Trotter
Caroline
C
Miller
Elizabeth
E
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood*; D002353:Carrier State / Q000453:epidemiology / Q000517:prevention & control; D002648:Child; D002675:Child, Preschool; D004739:England; D005260:Female; D006801:Humans; D032521:Immunity, Herd; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008589:Meningococcal Infections / Q000453:epidemiology* / Q000517:prevention & control*; D022401:Meningococcal Vaccines / Q000276:immunology*; D008875:Middle Aged; D015233:Models, Statistical; D011358:Product Surveillance, Postmarketing; D006113:United Kingdom / Q000453:epidemiology; D014852:Wales / Q000453:epidemiology; D055815:Young Adult
D000907:Antibodies, Bacterial; D022401:Meningococcal Vaccines; C410218:serogroup C meningococcal conjugate vaccine