A Pfizer vaccine that can protect unborn babies from the common seasonal respiratory syncytial virus (RSV) has been recommended for approval by FDA advisors.
The agency’s expert panel voted unanimously that the shot was effective in preventing severe illness from RSV in infants less than six months of age Thursday.
But four of the 14 panelists expressed concerns about whether the shot was safe, saying there was evidence it could increase the risk of premature labour.
The vaccine is given as a single dose to pregnant women in their second or third trimester and works by stimulating antibodies that fight RSV which can then be passed to babies in the womb via the placenta.
The FDA is still out to rule on the shot but could approve it as early as August just before RSV season, making it the world’s first RSV vaccine for infants. comes after agency He approved the world’s first vaccine for RSV earlier this month.
The FDA’s expert panel voted unanimously that the vaccine was effective, but concerns were raised about its safety profile. A decision from the FDA is expected in August, though it generally follows the advice of the expert panel
Almost all children become infected with RSV at least once by the time they are 2 years old, and most experience a mild, cold-like illness.
But the FDA says babies younger than six months are at particular risk of severe illness from the virus, which may be because their immune systems are still developing or they aren’t able to cough as forcefully as older babies.
The FDA says as many as 1 in 50 children in this age group are hospitalized with the virus, facing treatments including intravenous fluids and ventilators. Several hundred under-fives die from infection each year in the United States.
Pfizer’s vaccine — it’s called RSVpreF — works by exposing the mother to a protein from the surface of RSV, which triggers an immune reaction and the production of antibodies to fight off RSV.
Babies still in the womb can then be entered through the placenta. It can also be transmitted after birth through colostrum – the first milk an infant drinks from its mother.
It can last in an infant for up to six months, boosting defenses as the infant gradually builds up an immune system.
Other vaccines already use this system to stimulate immunity in infants, including the influenza vaccine and whooping cough vaccine.
All 14 members of the FDA panel voted that the vaccine was effective in preventing severe disease in infants when given to pregnant mothers, and ten out of 14 voted that its safety data was ‘generally favorable’ for use in pregnant women.
The US Food and Drug Administration will now decide whether to approve the vaccine, but Malignant usually follows the advice of its expert panel.
However, some members have raised concerns that the vaccine increases the risk of premature births.
Overall, the safety data was “reassuring,” said Dr. Paul Offit, a vaccine expert at Children’s Hospital of Philadelphia who has previously raised concerns about a Covid vaccine.
But he added, as CNBC reports, that “if you are in any way risking premature labor with this vaccine, I think there is going to be a heavy price to pay.”
He also noted that GSK had halted trials of a similar RSV vaccine in pregnant women after noting an uptick in premature births and neonatal deaths, or when a baby dies within the first 28 days of life.
Dr. Offit said that motion was “hung” on Pfizer’s RSV shots for babies.
If GSK really abandons a program on a similar, nearly identical vaccine, that will still be on hold [Pfizer’s] program.’
Dr. Jay Portnoy, medical director at Children’s Mercy Hospital in Kansas City, who voted in favor of the vaccine’s safety and efficacy, also warned that premature births could reduce the vaccine’s benefits.
“The problem is that if the baby is born early, this also reduces the effectiveness of the treatment because early birth means less antibodies are transferred,” he said.
So, this is a very complicated thing because now the harm makes the benefit less. There is an interaction between the two.
Babies born prematurely — before the 37th week of pregnancy — are at a higher risk of developing many health complications, including respiratory problems, infections, and developmental delays.

The graph above shows RSV-related hospitalizations in the United States by month and year. It swings between September and the end of spring – RSV season
The approval was based on data from the vaccine’s Phase 3 trial, which included 7,400 pregnant women — half of whom got the vaccine and the rest got a placebo.
This showed that it was 82 percent effective in preventing severe disease from RSV in newborns within the first 90 days of life.
The shot was also 70 percent effective during the first six months of life against severe disease.
But the study also showed that there was a greater risk of premature birth among mothers who got the vaccine compared to those who got a placebo.
In the vaccine group, nearly six percent of mothers had a premature birth, while in the placebo group, the number was 4.7 percent.
Pfizer said the difference was not statistically significant, but this still raises concerns for scientists.
In support of the safety of their vaccine, Pfizer’s Senior Vice President of Vaccine Research and Development, Dr. William Gruber, said:Certainly, in our view, there is no conclusive evidence to suggest that there is a risk of prematurity.
“So the question is, are you hostage to the potential benefits of the vaccine to something that you don’t have statistical significance at this point?
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