The potential role of pneumococcal conjugate vaccine in reducing acute respiratory inflammation in community-acquired pneumococcal pneumonia

Background: Pneumococcal conjugate vaccine (PCV) reduces both invasive pneumococcal disease (IPD) and other pneumococcal infections worldwide. We investigated the impact of stepwise implementation of childhood PCV programs on the prevalence of pneumococcal pneumonia, severity of acute inflammation, and associations between breakthrough pneumonia and pneumococcal serotypes in Taiwan. Methods: In total, 983 children diagnosed with community-acquired pneumococcal pneumonia were enrolled between January 2010 and December 2015. Results: Proportions of pneumococcal vaccinations increased each year in age-stratified groups with PCV7 (32.2%) as the majority, followed by PCV13 (12.2%). The proportion of pneumococcal pneumonia decreased each year in age-stratified groups, especially in 2-5 year group. Serotype 19A is the leading serotype either in vaccinated (6.4%) or unvaccinated patients (5.2%). In particular, vaccinated patients had significantly higher lowest WBC, lower neutrophils, lower lymphocytes and lower CRP values than non-vaccinated patients (p < 0.05). After stratifying patients by breakthrough infection, those with breakthrough pneumococcal infection with vaccine coverage serotypes had more severe pneumonia disease (p < 0.05). Conclusion: Systematic childhood pneumococcal vaccination reduced the prevalence of community-acquired pneumococcal pneumonia, especially in 2-5 year group. Serotype 19A was the major serotype for all vaccine types in patients with pneumococcal pneumonia and severity of acute inflammatory response was reduced in vaccinated patients.