7-Valent pneumococcal conjugate vaccination in England and Wales: is it still beneficial despite high levels of serotype replacement?
BACKGROUND
The UK introduced the 7-valent pneumococcal conjugate vaccine (PCV7) into the national vaccination program in September 2006. Previous modelling assumed that the likely impact of PCV7 on invasive pneumococcal disease (IPD) would be similar to the US experience with PCV7. However, recent surveillance data show a more rapid replacement of PCV7 IPD cases by non-PCV7 IPD cases than was seen in the US.


RESULTS
A previous model of pneumococcal vaccination was re-parameterised using data on vaccine coverage and IPD from England and Wales between 2006 and 2009. Disease incidence was adjusted for the increasing trend in reported IPD cases prior to vaccination. Using this data we estimated that individuals carrying PCV7 serotypes have much higher protection (96%;95% CI 72%-100%) against acquisition of NVT carriage than the 15% previously estimated from US data, which leads to greater replacement. However, even with this level of replacement, the annual number of IPD cases may be 560 (95% CI, -100 to 1230) lower ten years after vaccine introduction compared to what it may have been without vaccination. A particularly marked fall of 39% in children under 15 years by 2015/6 is predicted.


CONCLUSIONS
Our model suggests that PCV7 vaccination could result in a decrease in overall invasive pneumococcal disease, particularly in children, even in an environment of rapid replacement with non-PCV7 serotypes within 5 years of vaccine introduction at high coverage.
Immunisation, Hepatitis and Blood Safety Department, Health Protection Agency, London, United Kingdom. yoon.choi@hpa.org.uk
Yoon Hong
YH
Choi
Mark
M
Jit
Nigel
N
Gay
Nick
N
Andrews
Pauline A
PA
Waight
Alessia
A
Melegaro
Robert
R
George
Elizabeth
E
Miller
D015331:Cohort Studies; D016001:Confidence Intervals; D004739:England / Q000453:epidemiology; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D008954:Models, Biological; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000276:immunology / Q000635:transmission; D022242:Pneumococcal Vaccines / Q000276:immunology*; D015995:Prevalence; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000276:immunology; D013997:Time Factors; D014611:Vaccination; D014852:Wales / Q000453:epidemiology
D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines