A new study estimates that one death in every 50 deaths among healthy children under five years old worldwide is caused by a common virus currently spreading in the United States and Canada, the respiratory syncytial virus or RSV. In high-income countries, one in every 56 full-term healthy children will be hospitalized with RSV in the first year of life, according to researchers' estimates.

The study's authors, published Thursday in The Lancet Respiratory Medicine, wrote that the virus is particularly known to be dangerous for premature and medically vulnerable children, but it causes a "large burden of disease in infants worldwide."

Another study has examined the number of children with pre-existing conditions who were hospitalized with RSV, but the new study is one of the first to look at figures among healthy children. Co-author Dr. Louis Bont, Professor of Pediatric Infectious Diseases at the Wilhelmina Children's Hospital at the University Medical Center Utrecht in the Netherlands, said. Bont is also the founding president of ReSViNET, a non-profit organization dedicated to reducing the global burden of RSV infection.

The estimates are based on a study that looked at the number of RSV cases in 9,154 infants born between July 2017 and April 2020 who were followed during the first year of life. The children received care at health centers across Europe.

Also, about 1 in every 1,000 children in the study was placed in intensive care for breathing assistance from a ventilator. This care is vital: in parts of the world where hospital care is lacking, the risk of death is high. Bont said, "The vast majority of deaths due to respiratory syncytial virus occur in developing countries." "In the developed world, deaths are really rare, and if they occur, it is almost exclusively in those with severe underlying diseases. But in most places around the world, there is no intensive care unit."

Globally, RSV is the second leading cause of death during the child's first year of life after malaria. Bont said between 100,000 and 200,000 children die from the virus each year. Likewise, Dr. Christina Dieter, head of pediatrics at the University of Nevada, Reno, and a clinical pediatric specialist, said there are fewer RSV deaths in high-income countries, but the virus still causes significant morbidity, and even hospitalization can have serious consequences.