Is It Time To Review The Vaccination Strategy To Protect Adults Against Invasive Pneumococcal Disease

: Pneumococcal conjugate vaccines (PCVs) have reduced the predominant serotypes causing invasive pneumococcal disease (IPD). We assessed the impact of the paediatric 7- and 13-valent pneumococcal conjugate vaccines (PCV7 and PCV13) among older adults. We compared serotype-specific incidence rates from 2007/08 to 2016/17, expressed as incidence rate ratios (IRR). Introducing PCV7 and PCV13 into the childhood immunisation programme resulted in a decline in these serotypes in adults ≥65 years of age, with PCV7 serotypes decreasing by 85% (IRR=0.11, 95%CI: 0.05-0.22, p<0.0001) and PCV13 serotypes not included in PCV7 (PCV13-7), decreasing by 9% (IRR=0.68, 95%CI: 0.40-1.16, p=0.134). However, there was a significant increase in serotypes only found in the 23-valent polysaccharide vaccine, PPV23-PCV13: IRR=2.57, 95%CI: 1.68-4.03, p<0.0001, and non-vaccine types (NVTs), IRR=3.33, 95%CI: 1.75-6.84, p=0.0001. The decline of IPD associated with PCV7/13 serotypes and the increase in PPV23-PCV13 serotypes indicates clear serotype replacement. Increasing PPV23 uptake could still reduce the burden of disease for this population.