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.