Researchers in Belgium and Denmark have found something that changes how we think about asthma prevention: stopping RSV infection in infants could reduce asthma cases years later, especially in children with a family history of allergies.
The discovery comes from a study published in Science Immunology that combined data on every Danish child and their parents with controlled lab experiments. What they found was specific and actionable: when newborns get severe RSV infections in their first months, their immune systems learn to overreact to common allergens like house dust mites. For children already genetically primed toward allergies, this effect is even stronger.
How RSV reshapes immunity
Asthma affects 5–15% of children across Europe, disrupting daily life and straining families and healthcare budgets for years. Understanding what triggers it matters. "Childhood asthma is complex with many contributing factors," says Prof. Bart Lambrecht, senior author at VIB-UGent Center for Inflammation Research. "But we found that early RSV infection and genetic allergy risk interact in a very specific way that pushes the immune system toward asthma."
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Start Your News DetoxThe mechanism is elegant and troubling: infants inherit allergen-specific antibodies from their parents that prime their immune systems. When RSV arrives in those first vulnerable months, it amplifies this priming, creating an immune system that's primed to overreact to everyday allergens. The researchers tested what happens when you block this—and found that preventing RSV infection stopped the harmful immune changes entirely. In their models, asthma simply didn't develop.
The encouraging part: we now have tools to prevent RSV. Several countries are rolling out maternal vaccination during the third trimester of pregnancy, combined with long-acting antibodies given directly to newborns. These approaches are already highly effective at preventing RSV hospitalizations. The new research suggests they could prevent something bigger—the asthma cases that follow.
Adoption has been uneven so far, partly because RSV prevention was framed as a hospitalization-prevention strategy. "With this new evidence, the conversation changes," says Prof. Hamida Hammad, co-senior author. "Parents can choose RSV prevention knowing it protects not just the winter ahead, but their child's respiratory health for years to come."
The path forward depends on whether policy makers, pediatricians, and parents see asthma prevention as reason enough to expand access. If they do, the benefits could be substantial—fewer children struggling to breathe, fewer families managing a chronic condition, fewer healthcare systems bearing the long-term costs.
