Merck's shot will compete against a similar blockbuster treatment from Sanofi and AstraZeneca called Beyfortus.

In a major boost for infant health, the U.S. Food and Drug Administration (FDA) has approved ENFLONSIA ™ (clesrovimab-cfor), a new preventive treatment designed to protect newborns and babies from respiratory syncytial virus (RSV),

The U.S. Food and Drug Administration on Monday approved Merck's preventive antibody shot to protect infants up to one year of age from respiratory syncytial virus during their first RSV season, the company said.