The rate of pneumonia decreased among vaccine-eligible children and older, unvaccinated children after the introduction of the 10-valent pneumococcal conjugate vaccine (PCV10), according to a study published in PLoS One.
In September 2010, PCV10 was introduced into the Finnish Vaccination Program using a 2+1 schedule at 3, 5, and 12 months. Arto A. Palmu, MD, PhD, from the National Institute for Health and Welfare in Tampere, Finland, and colleagues conducted a nationwide, population-based, observational study to compare rates of pneumonia in children before and after the introduction of the Finnish National Vaccination Program.
The researchers followed a target cohort of vaccine-eligible children between 3 and 42 months of age. The participants were born after June 1, 2010, and followed until the end of 2013. The researchers also followed a cohort of older children between 7 and 71 months of age who were not eligible for the PCV vaccination from 2011 and 2013.
Both cohorts were compared with 2-season and age-matched reference cohorts before the introduction of the National Vaccination Program. The main outcome of the study was hospital-treated primary pneumonia, which was defined as primary diagnosis of pneumonia after in-patient hospitalization.
The rate of hospital-treated primary pneumonia episodes was 5.3 per 1,000 person-years in the combined reference cohorts and 4.1 per 1,000 person-years in the target cohort of vaccine-eligible children. The relative rate reduction in the target cohort was 23%, and the absolute reduction was 1.3 per 1,000 person-years compared with the reference cohort.
In the cohort of older children, the researchers observed an increase in hospital-treated pneumonia cases until 2011, and they observed a subsequent reduction of 18% between 2012 and 2013. They noted that the number of empyema diagnoses remained low.
“Although we collected hospital outpatient pneumonia visits, we did not have data on pneumonia diagnoses at the public or private ambulatory care outside hospitals,” the study authors noted. “Therefore, our data represent more severe cases of pneumonia requiring hospital referral.
“Surveillance data in the coming years will shed more light on the full potential of PCV10 in reducing pneumonia and other pneumococcal disease in the unvaccinated population,” they added.
- Palmu AA, Kokko-HR, Nohynek, Nuorti JP, Kilpi TM, Jokinen J. Impact of ten-valent pneumococcal conjugate vaccine on pneumonia in Finnish children in a nation-wide population-based study. PLoS One. 2017. doi:10.1371/journal.pone.0172690