A common and sometimes dangerous respiratory germ might also raise the risk of asthma if encountered early in life, new research this month suggests. The study found that children were more likely to develop asthma if they caught a respiratory syncytial virus (RSV) infection before the age of 1. The findings might highlight yet another benefit of effective vaccines and treatments for RSV that are expected to reach the public soon.
RSV is one of the most ubiquitous respiratory germs around, with most people expected to catch it by age 2. The infection usually causes mild cold symptoms, such as runny nose, coughs, and sneezing. But it has a higher risk of causing serious, even life-threatening, illness in the very young and old. According to the Centers for Disease Control and Prevention, RSV hospitalizes tens of thousands of Americans over the age of 65 and under the age of 5 every year.
For many years now, studies have suggested that severe RSV infections in childhood can raise people’s risk of asthma and allergies. But there’s still a lot we don’t understand about this connection, including the exact risk factors that might make children more susceptible to developing asthma following RSV infection. This new study, conducted by researchers in Tennessee, was designed to sniff out some of these factors.
The research is called the Infant Susceptibility to Pulmonary Infections and Asthma Following RSV Exposure, or INSPIRE, study. The researchers proactively followed around 1,700 healthy children born in the state between 2012 to 2013 for up to five years. Along the way, they tracked when and if the children were exposed to RSV infection and whether they were diagnosed with asthma by age 5.
Overall, around half of the children caught RSV in their first year of life, and these children were then more likely to develop asthma by the time they turned 5. Specifically, children who caught RSV in infancy had a 26% higher risk of having asthma than those who didn’t catch it as early. The team’s findings were published earlier this month in The Lancet.
Previous research has suggested that there’s a shared genetic component underlying the link between severe RSV and asthma. In other words, the same genetic variations that make a child more vulnerable to severe RSV infection also seem to make them more vulnerable to asthma. These new results don’t invalidate this past work, but they likely add a new wrinkle. As is often true in medicine, it might be both the environment and genetics that affect a child’s risk of developing asthma after RSV infection.
“We focused on the first year of life because we think the first year is a very important period of lung and immune development,” said study author Christian Rosas-Salazar, a pediatrician at Vanderbilt University Medical Center, in a statement from the university. “We believe that when a child is infected with RSV in the first year of life, when the lungs and immune system are still under development, that could lead to certain abnormalities that can later cause asthma.”
While the initial years of the pandemic saw a decline of many common infections, these germs—including RSV—have since returned in full force. RSV’s toll on the young and elderly has long made it an appealing target for vaccination and other treatments. After decades of failure, we’re finally on the brink of having several effective vaccines meant for older adults, newborns, and even pregnant mothers who can pass on their immunity to their children.
It’s unknown whether any of these vaccines can provide long-term protection yet, but they should substantially reduce the risk of severe illness prior to the RSV season (typically winter), much like the annual flu shot. And given the team’s findings here, it’s also worth finding out if childhood RSV vaccines can prevent RSV-related cases of asthma, the study authors say.
“We hope the results of this study motivate long-term follow-up of common respiratory outcomes among children in ongoing clinical trials of RSV prevention products, including vaccines and monoclonal antibodies that can decrease the severity of the infection,” Rosas-Salazar said.
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