Impact of ten-valent pneumococcal conjugate vaccine on pneumonia in Finnish children in a nation-wide population-based study

PLoS One. 2017 Mar 1;12(3):e0172690. doi: 10.1371/journal.pone.0172690. eCollection 2017.

Abstract

Background: The ten-valent pneumococcal conjugate vaccine (PCV10) was introduced into the Finnish National Vaccination Program (NVP) in September 2010 using a 2+1 schedule (3, 5, 12 months). We estimated the direct and indirect effects of PCV10 on pneumonia among children to evaluate the public health impact of the vaccine.

Methods: We conducted a nation-wide population-based, observational study comparing rates of pneumonia in children before and after the NVP introduction. For the total (direct and indirect) effect, the cohort of vaccine-eligible children (born June 1, 2010 or later) was followed until the end of 2013 (age range 3-42 months). For the indirect effect, a cohort of older children (age range 7-71 months) not eligible for the PCV vaccination was followed from 2011 to 2013. Both cohorts were compared with two season- and age-matched reference cohorts before NVP introduction. Hospitals' in- and outpatient discharge notifications with ICD-10 diagnoses compatible with pneumonia (J10.0, J11.0, J12-J18, J85.1 or J86) as set by the hospital pediatricians were collected from the national Care Register. The main outcome was hospital-treated primary pneumonia (HTPP), defined as primary diagnosis of pneumonia after in-patient hospitalization. We compared rates of pneumonia in the NVP target and reference cohorts by using Poisson regression models.

Results: The rate of HTPP episodes was 5.3/1000 person-years in the combined reference cohorts and 4.1/1000 person-years in the target cohort vaccine-eligible children. Compared with the reference cohort, the relative rate reduction in target cohort was 23% (95%CI 18-28) and the absolute reduction 1.3/1000 person-years. In the indirect effect evaluation, we observed continued increase in HTPP incidence until 2011 with a subsequent reduction of 18% (95%CI 10-25) during years 2012 to 2013. Number of empyema diagnoses remained low.

Conclusions: A substantial decrease in pneumonia rates was observed both among vaccine-eligible children and among older, unvaccinated children after PCV10 introduction.

MeSH terms

  • Age Factors
  • Child
  • Child, Preschool
  • Female
  • Finland / epidemiology
  • Follow-Up Studies
  • Humans
  • Infant
  • Male
  • Models, Biological*
  • National Health Programs*
  • Pneumococcal Vaccines / administration & dosage*
  • Pneumonia, Pneumococcal / epidemiology*
  • Pneumonia, Pneumococcal / prevention & control*
  • Registries*

Substances

  • Pneumococcal Vaccines

Grants and funding

The current study was funded by the National Institute for Health and Welfare (THL). The authors are employees of the National Institute for Health and Welfare, which has received research funding from GlaxoSmithKline for a Nationwide effectiveness trial of the ten-valent pneumococcal conjugate vaccine. AAP, HRK, TMK, and JJ are coinvestigators in the trial. GlaxoSmithKline had no role in the funding or conduct of the current study.