Expectant parents could soon have another new option this fall to protect their newborns from RSV, or respiratory syncytial virus, the most common cause of hospitalization in American infants, after the Food and Drug Administration announced Monday that it has widened its approval for Pfizer's Abrysvo vaccine to include expectant mothers.

Pregnant women would receive immunity from the shot during pregnancy then pass that along to their baby before birth, offering protection in the infant's earliest months of life.