Daily Dose: RSV Infection in Infancy & Risk of Asthma in Childhood

Patient Care brings primary care clinicians a lot of medical news every day—it’s easy to miss an important study. The Daily Dose provides a concise summary of one of the website's leading stories you may not have seen.

On April 25, 2023, we reported on a study published in The Lancet that examined the association between respiratory syncytial virus (RSV) infection during infancy and childhood asthma.

The study

Infants with non-low birthweight born at term between June and December 2012 or between June and December 2013 were recruited from 11 pediatric practices across middle Tennessee. Researchers ascertained RSV infection status in the first year of life via passive and active surveillance. Parents were contacted regularly, and infants underwent nasal washes and blood sampling at some health care encounters.

Participants were followed up prospectively for the primary outcome of 5-year current asthma, which researchers analyzed in all participants who completed the 5-year follow-up. A total of 1946 children (48% girls; median age, 55 days) were enrolled, of whom 1741 (89%) had available data to analyze RSV infection status in the first year of life. Among the 1741 participants with available RSV infection data, 54% (n=944) had been infected during infancy.

The findings

The proportion of children with 5-year current asthma was lower among those without RSV infection during infancy (91 [16%] of 587) than those infected with RSV during infancy (139 [21%] of 670; p=0.016).

Participants who were not infected with RSV during infancy had a 26% lower risk of 5-year current asthma compared to those who were infected during infancy (adjusted rate ratio [aRR] 0.74, 95% CI 0.58-0.94; P=.014). The estimated proportion of 5-year current asthma cases that could be prevented by avoiding RSV infection during infancy was 15% (95% CI 2.19-26.84).

A note from authors

"It is important to recognize that although our findings suggest a causal association, because of the observational design, our study can never definitively establish causality. Instead, our results highlight the need for long-term follow-up of common respiratory outcomes among children participating in ongoing and future clinical trials of agents for RSV immunoprophylaxis."

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