A child's severe RSV infection may increase the risk of asthma in early childhood

Respiratory syncytial virus (RSV) is one of the most common causes of respiratory infection in young children. Severe RSV infection in infancy has been associated with wheezing and asthma later in childhood. However, it has remained unclear whether RSV itself causes asthma, or whether the same children are inherently susceptible to both severe RSV infection and asthma.

A study by HUS, the University of Helsinki's Institute for Molecular Medicine Finland (FIMM), Finnish Institute for Health and Welfare, and Nordic collaborative partners investigated this question by combining national Finnish registry data with genetic analyses. The study included nearly a million children born in Finland between 1998 and 2014. The genetic component was based on genomic data from nearly 100,000 participants in Nordic genetic cohorts.

Post-RSV respiratory symptoms most commonly occurred at 1 to 2 years of age

The study investigated how many children with recurrent wheezing or asthma had been hospitalized with RSV during the first year of their life, and how their clinical characteristics differed from other children with asthma.

Children hospitalized due to RSV used more inhaled asthma medication at ages 1 to 2 years, but after the age of five they used less such medication than other children with recurrent wheezing or asthma. Children who had RSV infection also had lower eosinophil counts. Higher eosinophil counts are typically associated with a predisposition to allergies.

“The results indicate that recurrent wheezing or asthma related to RSV may be distinct from other similar symptoms. The symptoms appear to be concentrated in early childhood, and at least some children seem to outgrow them when they get older,” says Post-Doctoral Researcher and Specializing Physician in Pediatrics, Pekka Vartiainen.

A new genetic link behind severe RSV

The study discovered that familial factors related to predisposition to asthma did not increase infants’ risk of developing severe RSV. Instead, the researchers discovered that a gene locus named APBB1IP was associated with the risk of contracting the virus. The gene affects white blood cells’ ability to move towards the source of infection, which can have an impact on how easily a child falls ill with RSV infection. This study is the largest investigation to date on the effect of genetic factors on susceptibility to RSV infection.

RSV prevention has changed rapidly in recent years. New, long-acting antibodies given to infants are effective at preventing the severe outcomes of RSV infection. The antibody reduces the severity of RSV symptoms so significantly that severe cases of RSV in infants nearly disappear. 

“The next important step is to determine whether these antibodies also reduce respiratory symptoms later in childhood,” says Vartiainen.

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