Long-term population impact of infant 10-valent pneumococcal conjugate vaccination on invasive pneumococcal disease in adults in Finland. Issue 41 (29th September 2022)

• Record Type: Journal Article
• Authors: Nuorti, J. Pekka; Rinta-Kokko, Hanna; Toropainen, Maija; Siira, Lotta; Nohynek, Hanna; Palmu, Arto A.
• Is Part Of: Vaccine. Volume 40:Issue 41(2022)
• Page Start: 5950
• Page End: 5958
• Publication Date: 2022-09-29
• Subjects: Invasive pneumococcal disease -- Pneumococcal pneumonia -- Bacteremia -- 10-valent pneumococcal conjugate vaccine -- Indirect effects -- Adults -- time-series analysis; Vaccines -- Periodicals; 615.372
• DOI: 10.1016/j.vaccine.2022.08.047
• Languages: English
• ISSNs: 0264-410X

Abstract

Abstract: Background: Limited data are available on long-term indirect effects of ten-valent pneumococcal conjugate vaccine (PCV10) programmes. We evaluated changes in invasive pneumococcal disease (IPD) incidence, mortality, and serotype distribution in adults up to 9 years after infant PCV10 introduction. Methods: Culture-confirmed IPD cases ≥18 years (n = 5610; 85% were pneumonia) were identified through national, population-based laboratory surveillance; data were linked with population registry to conduct nationwide follow-up study. In a time-series model, we compared serotype-specific IPD incidence and associated 30-day mortality rates before and after PCV10 by using negative binomial regression models. Results: During pre-PCV10 period (7/2004–6/2010), overall IPD incidence in adults ≥18 years increased yearly by 4.8%. After adjusting for trend and seasonality, the observed PCV10 serotype IPD incidence in 7/2018–6/2019 was 90% (12/100, 000 person-years) lower than the expected rate without PCV10 program. Non-PCV10 serotype incidence was 40% (4.4/100, 000 person-years) higher than expected; serotypes 3, 19A, 22F, and 6C accounted for most of the rate increase. However, incidence of non-PCV10 IPD levelled off by end of follow-up. The observed-expected incidence rate-ratio (IRR) was 0·7 (95 %CI 0·5–0.8) for all IPD and 0·7 (95 %CI 0·3–1·3) for IPD-associated 30-day mortality. Case-fatality proportion decreased from 11·9% to 10.0% (p < 0.01). In persons ≥65 years, the IRR was 0·7 (95 %CI 0·5–0.95). Conclusions: Significant indirect effects were seen for vaccine-serotype IPD and for overall IPD in all adult age groups. For non-vaccine IPD, the incidence stabilized 5 years after infant PVC10 program introduction, resulting in a steady state in which non-vaccine IPD accounted for nearly 90% of overall IPD. Substantial pneumococcal disease burden remains in older adults.