Early RSV Infection Strongly Linked To Higher Childhood Asthma Risk, Scientists Report

An international research team has uncovered strong evidence that respiratory syncytial virus (RSV) infection in early infancy sharply raises the likelihood of developing asthma during childhood.

The increase in risk is even more pronounced in children who come from families with a history of allergies or asthma.

The findings, published in Science Immunology, indicate that shielding newborns from RSV could play a major role in lowering future asthma rates.

“Childhood asthma is a complex disease with many contributing factors,” said Prof Bart Lambrecht of the Flanders Institute for Biotechnology (VIB) and Ghent University in Belgium.

“We found that early-life RSV infection and genetic allergy risk interact in a very specific way that pushes the immune system toward asthma. The encouraging news is that this process can be prevented,” he added.

The project, which involved scientists from Denmark, matched comprehensive national health registry data covering all Danish children and their parents with detailed laboratory studies.

Their results showed a reinforcing relationship between early viral infection and inherited allergy risk.

How RSV and Allergy Risk Interact?

Babies who suffer severe RSV infection within their first months are more likely to develop overactive immune responses to common allergens such as dust mites.

This heightened response becomes significantly stronger when a family history of asthma or allergy is present, because allergen-specific antibodies passed from parents to the infant increase sensitivity even further.

Crucially, the researchers found that when they protected newborns from RSV in experimental settings, the harmful immune changes did not occur, and asthma did not develop.

“With RSV prevention now becoming widely accessible, we have an opportunity to improve long-term respiratory health, not just prevent RSV hospitalisations,” said Prof Hamida Hammad of VIB-UGent.

“This is not just a laboratory insight. It’s a message that should help parents choose RSV prevention with confidence,” she added.

Many countries are currently rolling out maternal vaccines given in the third trimester and long-acting antibody treatments for newborns.

Despite their effectiveness in preventing severe RSV illness, uptake remains uneven.

“This is a moment where policy, science, and paediatricians can come together,” Lambrecht noted. “If preventing RSV infection also reduces asthma risk, the benefits for families and health systems could be enormous.”

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