NASHVILLE, Tenn. — Respiratory syncytial virus (RSV) infection is the number one most common cause of both bronchiolitis and pneumonia in infants younger than one years-old. Now, new research suggests an RSV infection early in life may also raise a child’s risk of developing asthma years later.
The authors from Vanderbilt University Medical Center report RSV infection in the first year of life displays a connection to a significantly increased risk of asthma in children. This project is the first ever to analyze the effects of varying degrees of RSV infections on childhood asthma risk.
RSV is a seasonal respiratory virus incredibly common in kids; nearly all children contract the virus by the age of two and repeatedly throughout life. Symptoms are usually mild in most children and resolve in about a week’s time. However, RSV can also lead to serious illness and even death in premature or very young infants and those with either chronic lung disease or congenital heart disease.
RSV infection is the most common cause of hospitalizations worldwide when it comes to respiratory issues during the first year of a child’s life, according to Christian Rosas-Salazar, MD, MPH, assistant professor of Pediatrics in the Division of Allergy, Immunology and Pulmonary Medicine, the first author of the study.
Scroll down to see the 3 RSV symptoms that require hospitalization right away
“For 60 years investigators have repeatedly identified the link between severe RSV and asthma; however, we’ve shown that this link is explained in part by shared heredity to both severe RSV and asthma,” says the study’s principal investigator and senior author Tina Hartert, MD, MPH, professor of Medicine and Pediatrics, director of the Center for Asthma and Environmental Sciences Research, Vice President for Translational Research and the Lulu H. Owen Professor of Medicine. “The solution in our study was to understand the link between RSV and asthma by ensuring all RSV infections would be captured using molecular techniques and post-season serology.”
“In our study, among healthy children born at term, not being infected with RSV in the first year of life was associated with a substantially reduced risk of developing childhood asthma, which affects about 8% of the children in the U.S.,” Prof. Rosas-Salazar adds in a university release. “Our findings show an age-dependent association between RSV infection during infancy and childhood asthma.”
“We focused on the first year of life because we think the first year is a very important period of lung and immune development,” the researcher continues. “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.”
Avoiding RSV lowers asthma risk by a quarter
The INSPIRE (Infant Susceptibility to Pulmonary Infections and Asthma Following RSV Exposure) study followed 1,946 eligible healthy infants who were six months-old or younger at the beginning of RSV season (November to March in Tennessee). Researchers selected those infants from 11 pediatric practices across Middle Tennessee. The team administered bi-weekly surveillance and serology tests to classify infants as either infected or not infected during their first 12 months. Overall, 54 percent of infants contracted RSV during their first year of life, while 46 percent did not.
The study also tracked children annually, and eventually evaluated them for asthma at five years-old. Infants who did not have an RSV infection during first year of life had a 26-percent lower risk of asthma by their fifth birthday.
“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,” Prof. Rosas-Salazar notes.
“Showing efficacy of RSV vaccines against childhood asthma would increase public health interest and vaccine uptake,” Prof. Hartert concludes.
The study is published in The Lancet.
Spotting these 3 symptoms is critical for infants
An RSV infection usually starts to display symptoms within four to six days. For most people, the Centers for Disease Control and Prevention says these include runny nose, decrease in appetite, coughing, sneezing, fever, and wheezing.
Among generally healthy patients, the illness goes away on its own in a week or two. These patients are also unlikely to need hospitalization and there is currently no specific treatment for RSV, although scientists continue to work on a vaccine for the virus.
However, young infants who have no way of telling adults they’re feeling sick may not display these symptoms at first. According to the CDC, these are the only signs a baby with RSV may display:
- Decreased activity
- Breathing difficulties
A previous study suggests that older estimates of 120,000 infant deaths from RSV each year are actually much higher. When scientists included mortality rates from hospital data, the projections jumped up to one in every 10 deaths among infants under six months annually.