Pneumococcal vaccinations effectively prevent blood culture‐negative infections that resemble occult pneumococcal bacteraemia or bacteraemic pneumococcal pneumonia at one to 36 months of age

AIM: The occurrence of blood culture-positive pneumococcal bacteraemia and bacteraemic pneumonia decreased after large-scale pneumococcal vaccinations were introduced. The aim of this study was to evaluate the effect of pneumococcal vaccinations on hospitalisations due to blood culture-negative infections with fever and leucocytosis, without any other focus than pneumonic infiltration. MATERIAL: This was a retrospective hospital chart review covering the prevaccination era of 2008-2009 and postvaccination era of 2012-2013. The number of study subjects with fever and blood leucocytosis of >17.5 × 10E9/L at one to 36 months of age was 202. RESULTS: The incidence of hospitalisation for infections associated with fever and leucocytosis, when pneumonic infiltration was present on the chest radiograph, was 4.7/10 000/year, with a 95% confidence interval (95% CI) of 2.2-8.8 in children under 36 months in 2012-2013. When pneumonic infiltration was not present, the respective incidence was 14.6/10 000/year (95% CI: 9.6-21.1). The figure from the 2008-2009 prevaccination era was 11.3 (95% CI: 8.1-15.3) when pneumonic infiltration was present and 24.0/10 000/year (95% CI: 19.2-29.7) when pneumonic infiltration was absent. CONCLUSION: This study provides evidence of the effectiveness of pneumococcal vaccinations in preventing blood culture-negative infections that resembled occult pneumococcal bacteraemia (pneumococcaemia) or bacteraemic pneumococcal pneumonia at one to 36 months of age.