Respiratory syncytial virus (RSV) caused more than 100,000 deaths in children under age 5 years globally in 2019, according to an analysis published online in The Lancet.
Researchers, led by You Li, PhD, of Nanjing (China) Medical University, found that nearly half of those (more than 45,000) occurred in children younger than 6 months old.
They estimated that RSV causes 1 in 50 deaths among children under 5 years old, and 1 in 28 deaths in children under 6 months old.
Additionally, RSV is responsible for an estimated 3.6 million hospital admissions globally each year, according to the report.
This analysis is the first to sift RSV disease burden into narrow age brackets, the authors said.
The numbers highlight that almost all of the deaths (97%) were in low- and middle-income countries.
Messages for prevention
Tina Hartert, MD, MPH, a professor in the division of allergy, pulmonary, and critical care medicine at Vanderbilt University, Nashville, Tenn., who was not part of the study, wrote in an invited commentary that these findings will be important in RSV prevention.
Among the most notable findings, she wrote, is the heavy mortality in the 0- to 6-month age group, which she notes is “the age group targeted by vaccination during pregnancy and birth-dose immunoprophylaxis.”
Dr. Hartert, who coauthored the commentary with Justin R. Ortiz, MD, MS, with the Center for Vaccine Development and Global Health, University of Maryland, Baltimore, told this news organization, “RSV is a respiratory virus that infects nearly every child by the time they are 2-3 years of age, with severe infection and death most common in the youngest infants. Vaccines that prevent the most severe infections in these young infants will likely be one of the best ways to prevent these severe infections and death.”
Though the authors found most deaths occur in low- and middle-income countries, RSV is one of the most common reasons for infant hospitalization in the US and affects 1% to 3% of infants, half of whom are full-term and otherwise healthy, Dr. Hartert said.
It is also one of the most common causes of infant lower respiratory tract infection in young children in the United States, she said, and it causes the most severe disease at the age extremes, with older adults experiencing significant morbidity with RSV.
Dr. Li said in an interview that although the team did not focus on reporting country-specific estimates in this work, their previous work, resulted in estimates of 98,000-155,000 RSV-related hospitalizations in children under 5 years old in the United States in 2019. Between 65,000 and 86,000 were in infants less than 1 year old.
Currently, he said, the only available RSV prophylaxis is palivizumab (Synagis), which is expensive and given only to high-risk infants in high-income countries, including the United States.
“There have been a number of promising RSV prophylactic products including maternal vaccine and monoclonal antibodies that have the potential for targeting the general infant population – not just high-risk infants – in late-phase clinical trials,” he said. “Our estimates of RSV-related disease burden will help anticipate the impact of future RSV immunization programs.”