Study ties newborn RSV to childhood asthma 2023

Vanderbilt University Medical Center-led research aimed to establish a link between the respiratory virus RSV in neonates and asthma in 5-year-olds. The Lancet has published the article “Respiratory syncytial virus infection during infancy and asthma during childhood in the United States (INSPIRE): a population-based, prospective birth cohort study.” In the same journal issue, Marie-Nolle Billard and Louis J. Bont have published a Commentary.

944 (54%) of the 1,741 infants enrolled in the study had RSV infection in infancy. Children without RSV infection during infancy were less likely to have asthma at age 5 (91/587, 16%) than those with RSV infection during infancy (139/670, 21%).

In their analysis, infection with RSV during the first year of life was associated with a 26% increased risk of asthma at age 5 compared to infection at a later age. Researchers estimate that 15 percent of asthma cases in 5-year-olds could be prevented by averting RSV infection during infancy.

RSV-free status in the first year of life dramatically reduced pediatric asthma risk.

The results demonstrate an age-dependent association between reported RSV infection in infancy and the subsequent onset of childhood asthma. To conclusively establish causality, the authors state that the effect of interventions that prevent, delay, or reduce the severity of the initial RSV infection on pediatric asthma must be studied.

They could have just as easily indicated that RSV infections are more severe (less likely to be asymptomatic) in infants at risk for asthma, resulting in higher rates of health care interactions for respiratory infections.

RSV may cause childhood asthma.

However, the researchers prevented this dual interpretation by using blood samples at age 1 to ascertain previous RSV contraction rather than relying solely on health care interactions in their cohorts. Thus, a more specific population is measured, as opposed to merely comparing severe cases to RSV-free and symptomless cases.

The study also discovered intriguing severity-dependent associations between RSV infection during infancy across the entire disease severity spectrum and the risk of childhood asthma, which may support a dose-response association. In addition, there were associations between RSV infection and asthma risk that varied with age.

As always, correlation does not imply causation, but it is a good starting point for investigation. Future research can investigate the potential causal or correlative mechanisms underlying the findings of this study.