"Preventing these premature infants from contracting an RSV infection during their first winter had long-term benefits for their health," said Sally Wenzel, M.D., co-author and Professor of Medicine at National Jewish. "They have better lung function, and fewer colds, asthma attacks and allergies."
The children in the study were infants born 10 to 11 weeks prematurely, who spent weeks in intensive care and on ventilators. Their compromised lungs made them especially susceptible to infection with RSV, a common childhood illness. In healthy children, RSV usually develops into a relatively harmless upper respiratory infection. But in vulnerable children, such as these premature infants, the RSV infection is more likely to become a serious infection of the lungs. Thirteen of the children in the current study received monthly injections during their first winter of an immune globulin preparation with antibodies to RSV. The short-term trial showed that the preparation was effective at preventing RSV infection.
RSV infection of the lower respiratory tract has also been associated with the development of asthma. Dr. Wenzel and Eric Simoes, M.D., Professor of Pediatrics, Section of Infectious Diseases, at The Children's Hospital, decided to follow as many children from the original trial as possible to learn the long-term effects of RSV prevention in the first year of life. Seven to 10 years after the original trials, they found 13 of the 29 who had received the RSV preventive treatment. They compared them to 26 similar children, also premature infants with lung disease, who had not received the RSV preventive treatment. More then 80% (21/26) of the control group had had RSV infections of their lower respiratory tracts, compared to 15% (2/13) of the children who had received the immune globulin.
The children who received the RSV prevention had significantly less airway obstruction and better airway conductance. In one measure of general lung function, 85% (11/13) of the children who received the treatment had normal lung function compared to only 38% (9/26) of the control group. Children in the control group had an average of three colds in the previous year versus one for the RSV prevention group.
Children in the RSV prevention group had fewer asthma attacks and used less asthma medication in the previous year than did the control-group children. Children in the control group had an average of one asthma attack in the previous year, while those in the RSV prevention group had an average of none. Seventy percent (18/26) of the control children used an asthma medication in the previous year, compared to 40% (5/13) in the RSV prevention group. A smaller percentage of the children in the RSV prevention group were diagnosed with asthma, although the difference was not statistically significant.
"The children who received the RSV prevention are clearly healthier," said Dr. Wenzel. "Difficulty finding many of the children from the original study limited the size of our study sample and the statistical power of our study. But the consistency of the results, from lung function to colds to use of asthma medications makes me believe that RSV infection in the first year of life can contribute to the development of asthma."
One statistic especially favorable to the RSV/asthma connection is the higher rate of allergy among the control group. Allergies are more common among asthmatics and in many cases can trigger an asthma attack. Half (13/26) the control group of children demonstrated an allergy to one of 10 common allergens in the Denver area, while only 15% (2/13) of the RSV prevention group displayed any allergies.
"While this small study is not adequate to generally recommend preventive measures for RSV in the prevention of asthma, it strongly supports that approach in infants with underlying lung disease," said Dr. Simoes. Dr Simoes is involved in a large-scale European trial to determine whether prevention of RSV in premature infants can prevent subsequent asthma.