Vaccine Hopes for RSV, Leading Cause of Death in US Infants

Respiratory syncytial virus (RSV) is the leading cause of U.S. infant hospitalizations overall and across population subgroups, new data published in the Journal of Infectious Diseases confirm.

Acute bronchiolitis caused by RSV accounted for 9.6% (95% confidence interval, 9.4%-9.9%) and 9.3% (95% CI, 9.0%-9.6%) of total infant hospitalizations from January 2009 to September 2015 and October 2015 to December 2019, respectively.

Journal Issue Includes 14 RSV Studies

The latest issue of the journal includes a special section with results from 14 studies related to the widespread, easy-to-catch virus, highlighting the urgency of finding a solution for all infants.

In one study, authors led by Mina Suh, MPH, with EpidStrategies, a division of ToxStrategies in Rockville, Md., reported that, in children under the age of 5 years in the United States, RSV caused 58,000 annual hospitalizations and from 100 to 500 annual deaths from 2009 to 2019 (the latest year data were available).

Globally, in 2015, among infants younger than 6 months, an estimated 1.4 million hospital admissions and 27,300 in-hospital deaths were attributed to RSV lower respiratory tract infection (LRTI).

The researchers used the largest publicly available, all-payer database in the United States — the National (Nationwide) Inpatient Sample — to describe the leading causes of infant hospitalizations.

The authors noted that, because clinicians don’t routinely perform lab tests for RSV, the true health care burden is likely higher and its public health impact greater than these numbers show.

Immunization Candidates Advance

There are no preventative options currently available to substantially cut RSV infections in all infants, though immunization candidates are advancing, showing safety and efficacy in clinical trials.

Palivizumab is currently the only available option in the United States to prevent RSV and is recommended only for a small group of infants with particular forms of heart or lung disease and those born prematurely at 29 weeks’ gestational age. Further, palivizumab has to be given monthly throughout the RSV season.

Another of the studies in the journal supplement concluded that a universal immunization strategy with one of the candidates, nirsevimab (Sanofi, AstraZeneca), an investigational long-acting monoclonal antibody, could substantially reduce the health burden and economic burden for U.S. infants in their first RSV season.

The researchers, led by Alexia Kieffer, MSc, MPH, with Sanofi, used static decision-analytic modeling for the estimates. Modeled RSV-related outcomes included primary care and ED visits, hospitalizations, including ICU admission and mechanical ventilations, and RSV-related deaths.

“The results of this model suggested that the use of nirsevimab in all infants could reduce health events by 55% and the overall costs to the payer by 49%,” the authors of the study wrote.

According to the study, universal immunization of all infants with nirsevimab is expected to reduce 290,174 RSV-related medically attended LRTI (MALRTI), 24,986 hospitalizations, and cut $612 million in costs to the health care system.

The authors wrote: “While this reduction would be driven by term infants, who account for most of the RSV-MALRTI burden; all infants, including palivizumab-eligible and preterm infants who suffer from significantly higher rates of disease, would benefit from this immunization strategy.”

Excitement for Another Option

Jörn-Hendrik Weitkamp, MD, professor of pediatrics and director for patient-oriented research at Monroe Carell Jr. Children’s Hospital at Vanderbilt University, Nashville, Tenn., said in an interview there is much excitement in the field for nirsevimab as it has significant advantages over palivizumab.

RSV “is a huge burden to the children, the families, the hospitals, and the medical system,” he said.

Ideally there would be a vaccine to offer the best protection, he noted.

“People have spent their lives, their careers trying to develop a vaccine for RSV,” he said, but that has been elusive for more than 60 years. Therefore, passive immunization is the best of the current options, he says, and nirsevimab “seems to be very effective.”

What’s not clear, Weitkamp said, is how much nirsevimab will cost as it is not yet approved by the Food and Drug Administration. However, it has the great advantage of being given only once before the season starts instead of monthly (as required for palivizumab) through the season, “which is painful, inconvenient, and traumatizing. We limit that one to the children at highest risk.”

Rolling out an infant nirsevimab program would likely vary by geographic region, Kieffer and colleagues said, to help ensure infants are protected during the peak of their region’s RSV season.

The journal’s RSV supplement was supported by Sanofi and AstraZeneca. The studies by Suh and colleagues and Kieffer and colleagues were supported by AstraZeneca and Sanofi. Suh and several coauthors are employees of EpidStrategies. One coauthor is an employee of Sanofi and may hold shares and/or stock options in the company. Kieffer and several coauthors are employees of Sanofi and may hold shares and/or stock options in the company. Weitkamp reported no relevant financial relationships.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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