About

Study Background

We conducted the Respiratory Syncytial Virus (RSV) Prevention Phase II study to help us better understand if preventing RSV in infancy can reduce asthma in childhood. Respiratory syncytial virus (RSV) is the most important viral cause of lower respiratory tract infections (LRTI), like bronchiolitis and pneumonia, in children worldwide.

About RSV

RSV is a respiratory virus and infections generally occur in the fall, winter and spring. While most infants experience RSV infection during their first year of life, nearly all children will get RSV by the time they are two years old. In older children and young adults, RSV most often causes a cough or cold-like symptoms, but in infants, especially those younger than six months old, RSV infection can be more serious. It can cause pneumonia or inflammation of the airways, which may require hospitalization. American Indian and Alaska Native (AI/AN) infants are at increased risk of severe RSV compared to infants across the US. Prior to the introduction of RSV prevention products in fall 2023, 10% of Native American infants in the Southwest were hospitalized with RSV infections each year.

RSV disease in infancy can have lasting effects. Infants who experience severe RSV often continue to have breathing trouble or wheezing during the first few years of their life. Children who have severe RSV as babies are more likely to have asthma when they are older, but there are many things about the relationship between RSV and asthma that are not fully understood.

RSV Prevention

Researchers have been working on vaccines and monoclonal antibodies to prevent RSV for more than 50 years. Monoclonal antibodies are similar to vaccines, and can be given via injection to newborns to protect them when they are at greatest risk of complications from RSV LRTI. Now, there are several monoclonal antibodies and a maternal vaccine available to protect infants and young children from severe RSV disease. At the time of this study, no RSV prevention products were available. From 2004 to 2010, the CIH helped evaluate preventing RSV disease with a monoclonal antibody called motavizumab. 

Motavizumab was evaluated in more than 2,000 healthy, full term infants, and it reduced RSV-associated hospitalization by 87% in the babies who received it. The infants who participated in this study are now between 10 and 14 years old. Ten years later, we contacted families of the infants who participated in this study and invited them to participate in a brief follow up study called RSV prevention part II. The infants were now between 10 and 14 years old. With the consent of the parent or guardian, we administered a questionnaire to understand the child’s breathing and health, and well as reviewed their medical records to determine if they had asthma. 

The study found that 18.2% of children in the study had persistent asthma, which may be higher than the national estimates. More research is needed to understand the burden of asthma. Asthma was less common in children who had received the medication to prevent RSV infection: 19.7% of children who did not receive the medication had ongoing asthma, compared to only 17.5% of children who did receive the medication, but this was not statistically significant. While we can’t be sure that RSV prevention is associated with a reduced chance of childhood asthma, this study contributed to a growing amount of evidence that this may be the case. 

This study helped us better understand the relationships between RSV in infancy and asthma in childhood, provided important information for Navajo and White Mountain Apache communities in the Southwest, and helped build our understanding of the impact of RSV around the world.

This study was funded by the Gates Foundation.

Publication

https://pubmed.ncbi.nlm.nih.gov/40208934

We thank all study participants, IHS and tribal health facility medical staff, community members, the tribal ethical review boards, and the Gates Foundation for making this study possible.

Contact information

For more info, contact: Rachel Hartman rhartm16@jhu.edu

IRB #: NNHRRB NNR-04.151; PHX Area IRB 04.09; JHSPH IRB No. 8052