Serotype dynamics of invasive pneumococcal disease post-PCV7 and pre-PCV13 introduction in North East England

The 7-valent pneumococcal conjugate vaccine (PCV7) has been included in the routine childhood immunization programme in the UK since September 2006. A population-based study of serotypes causing invasive pneumococcal disease (IPD) post-PCV7 in North East England was conducted using data from a regional enhanced IPD surveillance system. Overall, there was a 20% reduction [95% confidence interval (CI) 5-32] from 12.1 cases/100 000 population in 2006/2007 to 9.7 in 2009/2010. There was a fall in IPD caused by PCV7 serotypes in all age groups, with reductions of 90% (95% CI 61-99) in children aged <5 years, 50% (95% CI 4-75) in persons aged 5-64 years and 66% (95% CI 40-82) in adults aged >= 65 years. There was a non-significant increase in IPD caused by non-PCV7 serotypes in children aged <5 years of 88% (95% CI - 10 to 312) and adults aged >= 65 years of 12% (95% CI - 19 to 50), which was largely caused by serotypes 7F, 19A and 22F. Replacement disease appears to have reduced the benefits of PCV7 in North East England.