Infant Respiratory Syncytial Virus Increases Bronchiolitis, Pneumonia Risks

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The development of respiratory syncytial virus (RSV) bronchiolitis in infants within the first 6 months of life was associated with increased odds of pneumonia, otitis media, and filling of antibiotic prescriptions in the second 6 months of life, according to study results published in Clinical Infectious Diseases.

This was a population-based cohort study of infants born at >35 weeks gestation between June 1 and December 31 of every year between 1995 and 2007. All infants included in the study were continuously enrolled in the Tennessee Medicaid Program during the first year of life. The researchers used the data gathered to determine variables predictive of bronchiolitis; RSV bronchiolitis was defined by International Classification of Diseases, Ninth Revision codes for acute bronchiolitis during a healthcare encounter.

A total of 123,301 infants were included in the study, of whom 6.8% had at least 1 healthcare visit for RSV bronchiolitis within the first 6 months of life. The infants who developed RSV bronchiolitis in the first 6 months of life, compared with infants who did not, were more likely to have pneumonia (3.4% vs 2.5%, respectively), otitis media (42.4% vs 35.6%, respectively), and/or filling of an antibiotic prescription (77.6% vs 74.2%, respectively) in the second 6 months of life. RSV bronchiolitis also increased the odds of developing pneumonia (adjusted odds ratio [aOR], 1.36; 95% CI, 1.20-1.54), otitis media (aOR, 1.32; 95% CI, 1.26-1.38), and filling of an antibiotic prescription (aOR, 1.24; 95% CI, 1.16-1.32). There was also a dose-dependent relationship observed between increasing severity of RSV bronchiolitis during the first 6 months of life as measured by the level of the healthcare encounter and the relative odds of developing pneumonia in the second 6 months of life.

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Acknowledged study limitations included the fact that investigators could not confirm RSV infections via laboratory testing and instead used a previously validated algorithm based on viral identification. Further, because otitis media and pneumonia were obtained using administrative data, there is a potential for misclassification.

The investigators concluded that the findings, “provide evidence of significant longer-term burden of non-wheezing respiratory outcomes in childhood following RSV bronchiolitis.” The results also supported the potential long-term effect of RSV vaccination programs in both low- and middle-income countries. However, further studies to confirm causality, including randomized clinical trials or observational follow-up following vaccine introduction are needed said investigators.


Abreo A, Wu P, Donovan BM, et al. Infant respiratory syncytial virus bronchiolitis and subsequent risk of pneumonia, otitis media, and antibiotic utilization [published online October 21 2019]. Clin Infect Dis. doi:10.1093/cid/ciz1033