Belgian researchers from VIB and Ghent University (UGent), together with colleagues from Denmark, have presented compelling evidence that infection with respiratory syncytial virus (RSV) in early infancy significantly increases the risk of developing asthma in children. This effect is especially pronounced in babies with a family history of allergies or asthma.

The study, published on November 28 in the journal Science Immunology, showed that protecting newborns from RSV can substantially reduce future asthma rates. In Europe, 5–15% of children suffer from asthma—a chronic disease that affects quality of life, places a heavy burden on families, and leads to significant societal costs. Therefore, finding effective ways to lower the risk of asthma before symptoms appear has become a key public health priority.

Professor Bart Lambrecht from the VIB-UGent Center for Inflammation Research, senior author of the study, notes: “Childhood asthma is a complex disease with many contributing factors. We found that early RSV infection and a genetic predisposition to allergies interact in a unique way, promoting the development of asthma. The good news is that this process can be prevented.”

To explore this connection, the team combined data from the national health registry of all Danish children and their parents with controlled laboratory studies. This approach allowed them to identify how early viral infections can amplify inherited allergy risks. The researchers discovered that infants who experienced severe RSV infection in their first months of life were more likely to develop immune responses that overreact to common allergens, such as dust mites. This tendency is even stronger in families with a history of asthma or allergies, as specific antibodies passed from parents to newborns further increase sensitivity.

An important part of the research showed that protecting newborns from RSV in experimental models completely prevented these immune changes, and asthma did not develop. Professor Hamida Hammad (VIB-UGent), co-author of the study, emphasizes: “Now that RSV prevention is becoming widely available, we have the opportunity to improve long-term respiratory health, not just prevent hospitalizations due to RSV. This is not just a laboratory finding—it’s a message that should help parents confidently choose RSV prevention.”

Maternal vaccination during the third trimester of pregnancy and passive immunization of newborns with long-acting antibodies are being introduced in many countries. However, the uptake of these methods remains uneven, despite their high effectiveness in preventing RSV-related hospitalizations. Professor Lambrecht adds: “Now is the time for policymakers, scientists, and pediatricians to come together. If preventing RSV infection also reduces asthma risk, the benefits for families and healthcare systems could be enormous.”