A clearer link between RSV and childhood asthma

Children who do not contract respiratory syncytial virus (RSV) during their first year of life are significantly less likely to suffer from asthma by age five, show results of the cohort INSPIRE study, which followed nearly 2,000 newborns for 10 years.“Childhood is a crucial period for lung and immune development. Determining whether preventing RSV infection can reduce the risk of childhood asthma is the key to implementing effective prevention strategies and reducing long-term respiratory morbidity in children,” said pediatrician Christian Rosas Salazar, lead author of the observational study published in The Lancet. To be selected into the INSPIRE cohort, children had to be healthy, without cardiovascular, pulmonary or neurological disease, born at term and with a birth weight greater than 2.25 kg. Read: Approaches to reduce inhaler-related greenhouse gas emissionsAs soon as a child met the criteria for an acute respiratory infection in their first year of life, the research team began evaluations, including a parent questionnaire, a physical examination of the child, a nasal swab and a analysis of medical records for those who had received health care.The presence of RSV was then confirmed or refuted by a PCR test. The study listed severe cases that caused bronchiolitis, but also milder cases. A serological test was carried out on all the participants at the age of one to measure the level of antibodies against RSV in their blood. The research showed that 54% of children had been infected. Researchers were also interested in the prevalence of asthma over subsequent years. To be considered asthmatic, the child had to have received a clinical diagnosis or medication for asthma.The analysis revealed that at the age of 5, 21% of children infected with RSV in their first 12 months of life were asthmatic compared to 16% of those who contracted the virus after age one. Therefore not having contracted RSV was “associated with a 26% lower risk of asthma at 5 years, compared to having been infected with RSV (adjusted RR 0- 74, 95% CI 0-58-0-94, p=0-014).”Read: China says a surge in respiratory illnesses is caused by flu and other known pathogensAmong those who had not been infected before a year, there were also much fewer cases of wheezing between one and four years of age.But how does respiratory syncytial virus cause long-term airway weakness? One of the hypotheses put forward concerns the microbiome. RSV-infected children who develop persistent wheezing may have a lower abundance of Lactobacillus in their upper respiratory tract. This bacteria could potentially have a protective effect on respiratory health.RSV infection during the first year of life would also affect the immune response of memory T lymphocytes, for at least least the two years following infection. Metabolic changes have also been observed and are believed to be attributable to a disruption of the epithelial barrier of the airways following infection. These changes could predispose children to allergies, acute respiratory infections and greater sensitivity to environmental irritants like air pollution; all factors contributing to increasing the risk of asthma.A child’s birth month could even predict their risk of developing a form of asthma if it is superimposed on the seasonality of RSV. The same research team found that children aged four months at the peak of RSV in the winter of 2008 were 29% more likely to suffer from asthma compared to one-year-olds. This reinforces the recommendation to avoid putting newborns in contact with people who suffer from contagious respiratory diseases.Researchers estimate that up to 15% of childhood asthma cases could be prevented by avoiding RSV infection before the age of one.This article was translated from French and originally ran in our sister publication Profession Santé.

A clearer link between RSV and childhood asthma

Register for free access or login.

Related Topics