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. 2025 Jan;114(1):83-91.
doi: 10.1111/apa.17405. Epub 2024 Aug 28.

Increased risk of bacterial pneumonia before and after respiratory syncytial virus infection in young children

Karin Strandell  1 , Samuel Videholm  1 , Andreas Tornevi  2 , Maria Björmsjö  1 , Sven Arne Silfverdal  1
Affiliations

Increased risk of bacterial pneumonia before and after respiratory syncytial virus infection in young children

Karin Strandell et al. Acta Paediatr. 2025 Jan.

Abstract

Aim: The burden of respiratory disease is great among children. This study aimed to examine the temporal relationship between hospitalisation for respiratory syncytial virus (RSV) and bacterial pneumonia.

Methods: A Swedish population-based cohort was created by combining data from the Swedish Medical Birth Register, the National Inpatient Register, the Cause of Death Register, the Total Population Register, and the Longitudinal Integration Database for Health Insurance and Labour Market Studies. Children born between 1998 and 2015 were included and followed for 2 years. We examined the temporal relationship between RSV hospitalisation and bacterial pneumonia using piecewise exponential models.

Results: The final cohort comprised 1 641 747 children, 48.5% were females. There were 23 632 RSV and 4722 bacterial pneumonia hospitalisations, with mean age of 137.8 and 424.2 days, respectively. RSV hospitalisation was associated with bacterial pneumonia with an adjusted incidence rate ratio (aIRR) of 3.18. The risk was highest in the first month after RSV hospitalisation, aIRR 11.19. The risk of bacterial pneumonia was elevated for 4 months after RSV hospitalisation and before RSV hospitalisation.

Conclusion: We found an increased risk for bacterial pneumonia hospitalisation in children hospitalised for RSV both before and after RSV hospitalisation, indicating a bidirectional relationship.

Keywords: Streptococcus pneumoniae; bacterial pneumonia; children; epidemiology; respiratory syncytial virus.

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Conflict of interest statement

SV and MB have received funding to their institution from MSD during the conduct of the study and serving on the advisory board for pneumococcal vaccines from MSD outside the submitted work. SAS has been involved in vaccine trials for MSD, and has participated in Ad board meetings on hexavalent, influenza, meningococcal, pneumococcal vaccines, paid to his Institution or personally but outside this work.

Figures

FIGURE 1
FIGURE 1
Temporal relationship between RSV hospitalisation and hospitalisation for bacterial pneumonia and pyelonephritis. Time was divided into nine different categories: more than 1 month before RSV hospitalisation, 1 month before RSV hospitalisation, monthly periods related to RSV hospitalisation up to 5 months after RSV hospitalisation, more than 5 months after RSV hospitalisation, and no RSV hospitalisation. Crude (blue circles) and adjusted analyses (red squares) of the associations between time to RSV hospitalisation and hospitalisation for bacterial pneumonia and pyelonephritis in children under 2 years of age. Incidence rate ratios are presented on a logarithmic scale. Vertical lines represent the 95% CIs around the point estimates. Crude analysis was controlled for age in months. The adjusted analysis was controlled for pregnancy characteristics, birth characteristics, maternal education, PCV‐status, seasonality, county of residence, time trends, and age in months.
See this image and copyright information in PMC

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