Introduction Limited data are available on population-level herd effects of infant 10-valent pneumococcal conjugate vaccine (PCV10) programmes on pneumonia. We assessed national trends in pneumococcal and all-cause pneumonia hospitalisations in adults aged ≥18 years, before and after infant PCV10 introduction in 2010.
Methods Monthly hospitalisation rates of International Statistical Classification of Diseases, 10th revision (ICD-10)-coded primary discharge diagnoses compatible with pneumonia from 2004–2005 to 2014–2015 were calculated with population denominators from the population register. Trends in pneumonia before and after PCV10 introduction were assessed with interrupted time-series analysis. Rates during the PCV10 period were estimated from adjusted negative binomial regression model and compared with those projected as continuation of the pre-PCV10 trend. All-cause hospitalisations were assessed for control purposes.
Results Before PCV10, the all-cause pneumonia rate in adults aged ≥18 years increased annually by 2.4%, followed by a 4.7% annual decline during the PCV10 period. In 2014–2015, the overall all-cause pneumonia hospitalisation rate was 109.3/100 000 (95% CI 96.5 to 121.9) or 15.4% lower than the expected rate. A significant 6.7% decline was seen in persons aged ≥65 years (131.5/100 000), which translates to 1456 fewer pneumonia hospitalisations annually. In comparison, hospitalisations other than pneumonia decreased by 3.5% annually throughout the entire study period.
Conclusion These national data suggest that herd protection from infant PCV10 programme has reversed the increasing trend and substantially decreased all-cause pneumonia hospitalisations in adults, particularly the elderly.
- bacterial infection
- respiratory infection
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Contributors Study concept and design: OO, AAP, JJ and JPN. Acquisition of data: HR-K and ER. Analysis and interpretation of data: OO, HR-K, AAP, JJ and JPN. Drafting of the manuscript: OO and JPN. Critical revision of the manuscript for important intellectual content: OO, HR-K, AAP, JJ and JPN. Statistical analysis: OO and HR-K. Obtained funding: JPN. Study supervision: JPN. Final approval: OO, HR-K, AAP, ER, JJ and JPN.
Funding The study was funded by The National Institute for Health and Welfare (THL), and Health Sciences, Faculty of Social Sciences, University of Tampere, Finland. The study was partially supported by the Integrated Monitoring of Vaccine in Europe (I-MOVE+) project, which has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 634446.
Competing interests OO and JPN: no conflict of interest. HR-K, ER, AAP, and JJ are employees of the National Institute for Health and Welfare, Department of Public Health Solutions, which has received research funding from GlaxoSmithKline for a nationwide effectiveness trial of the 10-valent pneumococcal conjugate vaccine. HR-K, AAP, ER, and JJ are coinvestigators in the trial.
Ethics approval National Institute for Health and Welfare (THL), Helsinki.
Provenance and peer review Not commissioned; externally peer reviewed.
Presented at The main findings were presented in part at the 10th International Symposium on Pneumococci and Pneumococcal Diseases, Glasgow, Scotland, 26–30 June 2016.
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