Pneumococcemia in children--a retrospective study before universal pneumococcal vaccinations

Invasive pneumococcal disease in Northern Alberta, not a Red Queen but a dark horse

BACKGROUND

The consequences of the introduction of various pneumococcal protein conjugate vaccines (PCV) for children and adults is poorly understood.

OBJECTIVE

We undertook a population-based cohort study of invasive pneumococcal disease (IPD) in Northern Alberta (Canada) from 2000 to 2014, years spanning pre-and early PCV (2000-2004) vs PCV-7 (2005-2009) vs PCV-13 (2010-2014) time periods.

DESIGN

We collected clinical, laboratory, and Streptococcus pneumoniae serotype information on all patients from 2000 to 2014. We determined changes in presentation, outcomes, serotypes, and incidence in children and adults across time periods.

SETTING

There were 509 cases of IPD in children, an 80% decrease over time. Rates of empyema (4.0-15.7%, p < 0.001), ICU admission (13.1-20%), and mortality (1.8-8.4%, p < 0.001) increased over time. There were 2417 cases of IPD in adults. Unlike children, incidence of IPD did not change nor did rates of empyema. ICU admissions increased (p = 0.004) and mortality decreased (18.7-16.5%, p = 0.002). The total number of serotypes causing IPD remained stable in children (22 vs 26 vs 20) while they decreased in adults (49 vs 47 vs 42).

CONCLUSIONS AND RELEVANCE

For children, PCV vaccination strategies resulted in decreased overall rates of IPD and we observed increased rates of empyema and mortality; for adults, there was no change in IPD rates although disease severity increased while mortality decreased. On a population-wide basis, our results suggest that current PCV vaccination strategies are associated with an overall decrease in IPD but disease severity seems to be increasing in both children and adults.

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.