Background Changes over the last 5 years (2013–18) in the serotypes implicated in adult pneumococcal pneumonia and the patient groups associated with vaccine-type disease are largely unknown.
Methods We conducted a population-based prospective cohort study of adults admitted to two large university hospitals with community-acquired pneumonia (CAP) between September 2013 and August 2018. Pneumococcal serotypes were identified using a novel 24-valent urinary monoclonal antibody assay and from blood cultures. Trends in incidence rates were compared against national invasive pneumococcal disease (IPD) data. Persons at risk of vaccine-type pneumonia (pneumococcal conjugate vaccine (PCV)13 and pneumococcal polysaccharide vaccine (PPV)23) were determined from multivariate analyses.
Findings Of 2934 adults hospitalised with CAP, 1075 (36.6%) had pneumococcal pneumonia. The annual incidence of pneumococcal pneumonia increased from 32.2 to 48.2 per 100 000 population (2013–18), predominantly due to increases in PCV13non7-serotype and non-vaccine type (NVT)-serotype pneumonia (annual incidence rate ratio 1.12, 95% CI 1.04 to 1.21 and 1.19, 95% CI 1.10 to 1.28, respectively). Incidence trends were broadly similar to IPD data. PCV13non7 (56.9% serotype 3) and PPV23non13 (44.1% serotype 8) serotypes were identified in 349 (32.5%) and 431 (40.1%) patients with pneumococcal pneumonia, respectively. PCV13-serotype pneumonia (dominated by serotype 3) was more likely in patients in the UK pneumococcal vaccination clinical risk group (adjusted OR (aOR) 1.73, 95% CI 1.31 to 2.28) while PPV23-serotype pneumonia was more likely in patients outside the clinical risk group (aOR 1.54, 95% CI 1.13 to 2.10).
Interpretation The incidence of pneumococcal CAP is increasing, predominantly due to NVT serotypes and serotype 3. PPV23-serotype pneumonia is more likely in adults outside currently identified clinical risk groups.
- community acquired pneumonia
- Streptococcus pneumoniae
- pneumococcal conjugate vaccine
- pneumococcal polysaccharide vaccine
- replacement serotypes
- risk groups
- pneumococcal pneumonia
- non-invasive pneumococcal disease
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Contributors HJP, CS and WSL were responsible for study conception and design. HJP, PD, CR, TB, DA, HL, VB, RCE-P, CS and SE were responsible for data acquisition. HJP, TMM and CT were responsible for the statistical analysis. HJP and WSL drafted the initial versions of the Article. All authors contributed to data interpretation and read, commented on and approved the final version of the article.
Funding This study is independent research supported by the Nottingham National Institute for Health Research Biomedical Research Centre (NIHR BRC) and arising from an unrestricted investigator-initiated research grant from Pfizer. The study concept was developed and agreed by the authors with no input from the funding bodies; Pfizer had no part in the design or execution of the study, the analysis and interpretation of the results, the writing of this manuscript or the decision to submit for publication. The data are the sole responsibility of the authors and the sponsor for the study was Nottingham University Hospitals NHS Trust.
Disclaimer The views expressed in this publication are those of the authors and not necessarily those of the NHS, the NIHR or PHE.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval Study procedures were approved by the Nottingham Research Ethics Committee (REC reference 08/H0403/80).
Provenance and peer review Not commissioned; externally peer reviewed.
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