Pfizer's vaccine against respiratory syncytial virus, or RSV, is highly effective at protecting newborns when the shot is given to the mothers late in their pregnancy, according to clinical trial data published Tuesday.
RSV is a common respiratory virus that generally causes mild cold-like symptoms, but it can be dangerous for infants younger than 6 months.
The vaccine was well tolerated with no safety concerns for the mothers or their newborns, according to Pfizer.
Infants almost always show symptoms, but for babies younger than six months these symptoms can be more subtle, according to the CDC.
Irritability, decreased activity and appetite, as well as pausing while breathing are all signs that an infant might have RSV, according to the CDC.