F.D.A. Approves R.S.V. Shot for Infants

The Food and Drug Administration on Monday approved a shot to protect infants and vulnerable toddlers against respiratory syncytial virus, or R.S.V., offering one of the first protections for an illness that fills children’s hospitals year after year.

The monoclonal antibody shot is expected to be available at the start of the fall R.S.V. season. The F.D.A. is also considering approval of an R.S.V. vaccine by Pfizer for pregnant women that is meant to protect infants from the virus.

The treatment approved on Monday, called Beyfortus by its developers Sanofi and AstraZeneca, addresses an illness that can be severe in older adults and young infants. About 80,000 children ages 5 and younger are hospitalized with the virus each year, according to the Centers for Disease Control and Prevention.

“R.S.V. can cause serious disease in infants and some children and results in a large number of emergency department and physician office visits each year,” Dr. John Farley, an official in the F.D.A. Center for Drug Evaluation and Research, said. “Today’s approval addresses the great need for products to help reduce the impact of R.S.V. disease on children, families and the health care system.”

The potential to blunt the effects of R.S.V. will extend to older adults: In recent months, the F.D.A. has approved two vaccines against the virus for adults 60 and older. The virus is linked to 60,000 hospitalizations and up to 10,000 deaths each year in people 65 and older, according to the C.D.C. The agency estimated that more than 21,000 people in that age group would need to take the GSK vaccine to prevent one R.S.V. death in one year; the number was nearly 25,000 for the Pfizer shot.

Agency advisers considering the antibody shot for infants cast a unanimous vote in June in favor of approving the treatment for infants. More than 3,200 infants were given the shot in studies that Sanofi and AstraZeneca submitted to the F.D.A. One six-month study found that efficacy against very severe R.S.V. that required medical attention was 79 percent.

F.D.A. advisers were more cautious about an R.S.V. shot by Pfizer intended for pregnant women. In May, a panel voted 10 to 4 that the vaccine was safe, a reflection of concerns about slightly elevated rates of preterm births among mothers who received the vaccine, compared with those who received a placebo.

Studies of a similar vaccine by GSK were halted after researchers detected an increase in preterm births. The agency has yet to make a decision on that maternal Pfizer vaccine, called Abrysvo, though a company spokeswoman said that approval was anticipated in the coming weeks.