The impact of pneumococcal vaccination on bacterial and viral pneumonia in Western Australian children: record linkage cohort study of 469,589 births (1996–2012)

Abstract

Background

Pneumococcal conjugate vaccine (PCV) was included in Australia's National Immunisation Program for all children from 2005. We assessed the impact of PCV on all-cause and pathogen-specific pneumonia hospitalisations in Western Australian (WA) children aged ≤16 years.

Methods

All hospitalisations with pneumonia-related ICD-10AM diagnosis codes occurring in WA-born children (1996–2012) were linked to pathology records. Age-specific incidence rate ratios and temporal trends for all-cause and pathogen-specific pneumonia hospitalisations were calculated pre- and post-PCV introduction.

Results

469,589 births had 15,175 pneumonia-related hospitalisations. Hospitalisation rates were 6.7 (95%CI:6.4–6.9) times higher in Aboriginal than in non-Aboriginal children. Following PCV introduction, all-cause pneumonia hospitalisations showed significant declines across all age groups. A pathogen was identified in 2785 (41.6%) of 6693 pneumonia hospitalisations that linked to a pathology record. Respiratory syncytial virus (RSV) was most frequently identified with RSV-associated pneumonia hospitalisation rates of 89.6/100,000 child-years in Aboriginal and 26.6/100,000 child-years in non-Aboriginal children. The most common bacterial pathogen was Streptococcus pneumoniae in Aboriginal children (32.9/100,000) and Mycoplasma pneumoniae in non-Aboriginal children (8.4/100,000). Viral pneumonia rates declined in all children following PCV introduction, with the greatest declines seen in non-Aboriginal children; declines in bacterial pneumonia were observed in non-Aboriginal children.

Conclusions

Based on our ecological analyses, PCV seems to have had an impact on hospitalisations for pneumonia suggesting that the pneumococcus is likely to play a role in both bacterial and viral pneumonia. Respiratory viruses remain an important pathogen in childhood pneumonia. Vaccines targeting respiratory viruses are needed to combat the residual burden of childhood pneumonia.