Protecting babies against this common virus may help prevent childhood asthma, study says

Babies who fall severely ill with a common virus are much more likely to develop asthma in childhood – particularly if allergies or asthma run in their families, new research has found.

Scientists believe that infection with the respiratory syncytial virus (RSV) in infancy and genetic allergy risks interact in a way that makes children more susceptible to asthma, a chronic condition that causes inflammation and swelling in the airways of the lungs.

That means protecting newborns against RSV could help to blunt the toll of asthma later on, according to the study, which was published in the journal Science Immunology.

“This study underscores how the immune system is uniquely vulnerable in the very first weeks of life,” said Hamida Hammad, one of the study's authors and a research lead at the VIB-UGent Center for Inflammation Research (IRC).

“A single viral insult during this window can shape respiratory health for years,” she told Euronews Health in written comments.

RSV typically causes mild, cold-like symptoms, but it can be more dangerous for babies under six months old. It sends around 213,000 children under age five to the hospital each year in the European Union, Norway, and the United Kingdom.

Meanwhile, 5.7 per cent of EU residents have been diagnosed with asthma, the latest data shows. Rates range from 1.5 per cent in Romania to 9.4 per cent in Finland.

The researchers said finding ways to prevent asthma, which has no cure, is a major public health priority.

They analysed health data from all children born in Denmark between 1994 and 2018, and conducted controlled laboratory experiments to identify the relationship between early viral infections and genetic allergy risks.

Newborns who were hospitalised with RSV infections were three times as likely to be diagnosed with asthma as babies who were not hospitalised – and the risks were even higher for severely ill babies whose parents had asthma.

Other scientists have identified a link between RSV and childhood asthma, but it has been difficult to prove that the virus directly causes the condition.

In experimental models using mice, the researchers found that viral infections trigger immune changes, making newborns more vulnerable to common allergens such as house dust mites. They also found that mothers with allergies transfer related antibodies to their babies, which further raises their sensitivity to these irritants.

The researchers said the findings could help encourage RSV vaccination, given that it may help boost children’s respiratory health in the long-term.

“If preventing RSV infection also reduces asthma risk, the benefits for families and health systems could be enormous,” said Dr Bart Lambrecht, one of the study’s authors and IRC’s science director.

In 2023, the European Union approved the first RSV vaccine to protect babies up to six months old. When women are immunised during pregnancy, the vaccine generates antibodies that transfer to the developing foetus.

Health authorities recommend the jab for pregnant women in Belgium, France, Luxembourg, and Slovenia, but uptake is uneven.

“This is a moment where policy, science, and paediatricians can come together,” Lambrecht said.