The first vaccine to protect children from respiratory syncytial virus, or RSV, moved one step closer to Food and Drug Administration approval with positive votes Thursday from a panel of experts.

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Kateryna Kon/Getty Images/Scientific Photo Library

The first vaccine to protect children from respiratory syncytial virus, or RSV, moved one step closer to Food and Drug Administration approval with positive votes Thursday from a panel of experts.

Kateryna Kon/Getty Images/Scientific Photo Library

Food and Drug Administration advisers have recommended the agency approve the first vaccine to protect children from RSV, or respiratory syncytial virus. But some of the experts have expressed reservations about the adequacy of the data to support the vaccine’s safety.

In a two-part ballot, the experts voted unanimously, 14-0, that the available data supports the efficacy of Pfizer’s vaccine in preventing serious RSV-related respiratory disease. They then voted 10-4 that the data support the safety of the vaccine.

RSV is a leading cause of childhood hospitalization in the U.S. Each year, 58,000 to 80,000 children under the age of 5 are hospitalized with RSV infections, according to the Centers for Disease Control and Prevention. Children 6 months of age and younger are at high risk of severe RSV disease.

The votes came after a day of testimony and discussions at a public meeting of the agency’s vaccine expert panel. The FDA is not required to follow the advice of its expert panels, but it usually does. A decision on the vaccine for newborns is expected by the end of August.

The vaccine is not given to children. Instead, pregnant people are immunized during the late second and third trimesters of pregnancy. The antibodies that develop against RSV pass to the fetus in utero and subsequently protect the newborn.

A clinical trial involving 7,400 people found that the vaccine was 81.8% effective in preventing severe respiratory illness caused by RSV within three months of birth and 69.4% in the first six months.

There was some evidence that those who were vaccinated might have been more likely to give birth prematurely. And committee members were concerned about pregnant people receiving the vaccine at the same time as other vaccines, such as TDAP (tetanus-diphtheria-pertussis), because it could interfere with their effectiveness.

« I fear that if preterm births were somehow a consequence of this vaccine, it would be tragic, » said Dr. Paul Offit, a professor of pediatrics at Children’s Hospital of Philadelphia. He voted no on the adequacy of safety data.

Pfizer’s vaccine itself is under review by the FDA to protect people 60 and older from RSV. Councilors voted to approve the vaccine at their February meeting.

Separately, in a first, the the agency approved an RSV vaccine from drugmaker GSK in early May for people aged 60 and over.