A new study entitled “Respiratory Syncytial Virus–Associated Mortality in Hospitalized Infants and Young Children” reports that infant deaths due to respiratory syncytial virus are highly uncommon in the 21st century. The study was published in the journal Pediatrics.

Respiratory syncytial virus (RSV) is a common infection that affects children, and is characterized by infection of both lungs and airways. While healthy individuals usually experience mild symptoms, children and older adults can experience serious symptoms . In fact, RSV is a major cause of bronchiolitis and pneumonia in children less than 1 years old in the United States, that can even lead to death. However, unlike influenza where children’s death rates are tracked, child mortality due to RSV is not tracked by public health agencies. Therefore, the impact on children mortality is currently unknown.

In this study, the authors aimed to identify RSV-associated mortality in hospitalized children less than 2 years old, and to understand which conditions are associated with RSV mortality in these children.

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The authors retrieved data regarding pediatric hospitalizations associated with codes for RSV infection (according to the International Classification of Diseases, Ninth Revision, Clinical Modification) from national pediatric databases — the Agency for Healthcare Research and Quality (AHRQ) and Healthcare Cost Utilization Project (HCUP) Kids’ Inpatient Database (KID) and the Pediatric Health Information System (PHIS) database — from 2009 to 2011. They focused on studying data of child hospitalizations (less than 2 years old) related to RSV pneumonia, RSV bronchiolitis and bronchiolitis or other.

In total, the authors identified 607,937 RSV-associated admissions in the KID database, and 264,721 RSV-associated admissions in the PHIS database. The authors found that the RSV mortality rate decreased significantly with time and that RSV-associated hospitalizations are uncommon, only registering 3 to 4 admissions for every 10,000 admissions related to a primary diagnosis of RSV, according to the KID and PHIS databases, respectively. The KID 2009 data set registered 121 annual deaths, and the PHIS data set from 2000 to 2011 registered 56, representing a decrease in the order of 5 to 100 times less than 20th century estimates.

The authors concluded that the number of RSV-associated deaths in children with a primary diagnosis of RSV is comparable to the deaths associated with influenza infection in children who are less than 2 years old, and that the decrease observed is probably attributed to the increased implementation of medical care.

Since medications for RSV are highly costly, the authors’ findings can advance a more sustainable and targeted use of these therapies.

Carrie Byington, M.D., professor of pediatrics at the University of Utah and the study fist author noted, “The use of these medications has been controversial. This research may help guide more appropriate use of these costly medications for the infants and young children most at risk for developing severe complications.”