Elucidating the impact of the pneumococcal conjugate vaccine programme on pneumonia, sepsis and otitis media hospital admissions in England using a composite control

Dominic Thorrington*, Nicholas Andrews, Julia Stowe, Elizabeth Miller, Albert Jan Van Hoek

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)

Abstract

Background: The seven-valent pneumococcal conjugate vaccine (PCV) was introduced in England in September 2006, changing to the 13-valent vaccine in April 2010. PCV impact on invasive pneumococcal disease (IPD) has been extensively reported, but less described is its impact on the burden of pneumonia, sepsis and otitis media in the hospital. Methods: Using details on all admissions to hospitals in England, we compared the incidence of pneumococcal-specific and syndromic disease endpoints in a 24-month pre-PCV period beginning April 2004 to the 24-month period ending March 2015 to derive incidence rate ratios (IRRs). To adjust for possible secular trends in admission practice, IRRs were compared to the IRRs for five control conditions over the same period and the relative change assessed using the geometric mean of the five control IRRs as a composite, and individually for each control condition to give the min-max range. Relative changes were also compared with IRRs for IPD from the national laboratory database. The effect of stratifying cases into those with and without clinical risk factors for pneumococcal infection was explored. Results: Relative reductions in pneumococcal pneumonia were seen in all age groups and in those with and without risk factors; in children under 15 years old reductions were similar in magnitude to reductions in IPD. For pneumonia of unspecified cause, relative reductions were seen in those under 15 years old (maximum reduction in children under 2 years of 34%, min-max: 11-49%) with a relative increase in 65+ year olds most marked in those with underlying risk conditions (41%, min-max: 0-82%). Reductions in pneumococcal sepsis were seen in all age groups, with the largest reduction in children younger than 2 years (67%, min-max 56-75%). Reductions in empyema and lung abscess were also seen in under 15 year olds. Results for other disease endpoints were varied. For disease endpoints showing an increase in raw IRR, the increase was generally reduced when expressed as a relative change. Conclusions: Use of a composite control and stratification by risk group status can help elucidate the impact of PCV on non-IPD disease endpoints and in vulnerable population groups. We estimate a substantial reduction in the hospitalised burden of pneumococcal pneumonia in all age groups and pneumonia of unspecified cause, empyema and lung abscess in children under 15 years of age since PCV introduction. The increase in unspecified pneumonia in high-risk 65+ year olds may in part reflect their greater susceptibility to develop pneumonia from less pathogenic serotypes that are replacing vaccine types in the nasopharynx.

Original languageEnglish
Article number13
JournalBMC Medicine
Volume16
Issue number1
DOIs
Publication statusPublished - 8 Feb 2018

Bibliographical note

Funding Information:
Dominic Thorrington's position at Public Health England is funded by the I-MOVE+ (Integrated Monitoring of Vaccines in Europe) project that received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement #634446. Albert Jan van Hoek's research is supported by the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Immunisation at the London School of Hygiene & Tropical Medicine in partnership with Public Health England (PHE). The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR, the EU H2020, the Department of Health or Public Health England. The funders have had no input into this study in terms of study design, analysis of the data or writing of the manuscript.

Keywords

  • Composite controls
  • Herd immunity
  • Hospital Episode Statistics
  • Impact assessment
  • Indirect protection
  • Invasive pneumococcal disease
  • Non-invasive disease
  • Otitis media
  • Pneumococcal conjugate vaccine
  • Pneumonia
  • Post vaccination
  • Sepsis
  • Vaccine impact

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