Wondering about an RSV vaccine? Studies show promising results

Older adults and infants could soon be immunized against RSV as regulators consider the latest data from Pfizer on safety and effectiveness.
A child suffering from RSV (respiratory syncytial virus) in the hospital.
Posted at 2:09 PM, Apr 06, 2023

Two studies released Wednesday in the New England Journal of Medicine indicate the prospects of a vaccine for RSV are promising. 

The studies looked at Pfizer’s RSV vaccine candidates.One study on adultsages 60 and up found the vaccine was 66.7% effective against RSV. The study noted no evident safety concerns. 

Pfizer said it expects regulators to decide whether to authorize the vaccine for older adults at a meeting in May. In February, an FDA advisory committee voted by a 7-4 margin that the vaccine is safe and effective. 

At the committee’s Feb. 28 meeting, official meeting minutes indicated “several committee members noted that there was a paucity of evidence of the effectiveness in preventing severe outcomes, such as hospitalization, particularly in the highest at-risk populations.”

University of Southern California student pharmacist Bethanie Pan

Why isn't there an RSV vaccine?

In a press release, Pfizer says its maternal shot was 69% effective in preventing severe RSV infection in infants 0-6 months.


A second study involved administering the vaccine to pregnant women, who then would pass on the antibodies to their children. The study found the vaccine to be 81.8% effective in infants 90 days after birth, and 69.4% effective 180 days after birth. 

Like the study in older adults, there were no known safety concerns. 

Pfizer said it expects the vaccine to be up for consideration in August.

According to the Centers for Disease Control and Prevention, RSV causes 58,000 hospitalizations annually among children under age 5.

The CDC said those most at risk for RSV include premature infants; very young infants, especially those 6 months and younger; and children younger than 2 years old with chronic lung disease or congenital heart disease. 

Adults and older children who are healthy tend to have mild cases if infected. Early symptoms tend to include a runny nose, a decrease in appetite, and cough. Those symptoms can worsen, causing inflammation of the small airways in the lung.