The U.S. Centers for Disease Control and Prevention's (CDC) advisory committee on Friday recommended that expectant mothers receive the Pfizer vaccine against respiratory syncytial virus (RSV) during the late stage of their pregnancies.
Dr. Cohen called the vaccine "another new tool" that can be used this fall and winter "to help protect lives."
RSV is responsible for numerous hospitalizations and fatalities among infants in the United States. Last week, the CDC warned that a combination of COVID-19, RSV, and influenza at the same time could overwhelm hospitals and place a burden on the U.S. health care system this winter.
In August, the Pfizer bivalent vaccine, known as Abrysvo, received approval from the Food and Drug Administration (FDA) for use in pregnant women, having already received approval in July for use in adults aged 60 and older.
Abrysvo is a first-of-its-kind single-dose injection administered into the muscle and was specifically approved for use at 32 through 36 weeks of pregnancy.
According to the FDA, pregnant women who receive immunity from the shot will pass that immunity along to their unborn baby before birth via the placenta, thus protecting them from lower respiratory tract disease (LRTD) and severe LRTD caused by RSV until at least the age of six months.
RSV is typically mild in healthy adults but poses a significant threat to children under the age of five.
In most healthy adults it usually causes mild illness and symptoms such as a runny nose, decreased appetite, coughing, wheezing, and fever. Generally, individuals recover within a couple of weeks, according to the CDC.
While it often causes cold-like symptoms in infants and young children, as it does in adults, it can also lead to serious LRTD such as pneumonia and bronchiolitis (swelling of the small airway passages in the lungs).
In the United States, RSV is responsible for up to 80,000 hospitalizations and up to 300 deaths annually among young children, with nearly 80 percent of affected children having no underlying medical conditions, according to the CDC.
Last year, a surge in severe RSV infections overwhelmed children's hospitals.
The CDC advisory committee recommended that pregnant women receive the Abrysvo vaccine between September and January, a period when RSV rates are historically at their highest.
Additionally, another RSV protection option for babies, an injectable drug called Beyfortus, was approved during the summer.
Beyfortus delivers a dose of antibodies directly into the infant's bloodstream and is recommended for all babies up to eight months old entering their first RSV season, as well as for infants aged eight to 19 months at higher risk of severe disease during their second season.
The committee noted that most babies won't require both Abrysvo and Beyfortus.
Concerns Over Side EffectsMeanwhile, some concerns have been raised regarding the potential safety risks of the Pfizer maternal RSV vaccine.
During a phase three trial, a slightly higher rate of premature births occurred among mothers who received the vaccine compared to those who received a placebo.
This difference was not considered statistically significant.
The clinic trial data presented by the FDA was conducted among approximately 3,500 pregnant women. For pregnant women in the study who were 32 to 36 weeks pregnant, Abrysvo led to a 34.7 percent reduction in LRTD risk and a 91.1 percent reduction in severe LRTD risk within 90 days after birth, according to the FDA.
However, certain side effects were reported among pregnant women who received the shot, including pain at the injection site, headache, muscle pain, and nausea, the FDA said.
Additionally, although not commonly reported, a dangerous hypertensive disorder, known as pre-eclampsia—a serious blood pressure condition that sometimes develops during pregnancy—occurred in 1.8 percent of pregnant individuals who received Abrysvo compared to 1.4 percent of pregnant individuals who received a placebo, the FDA said.
Pre-eclampsia can be life-threatening to both the mother and the baby.
Pfizer has submitted additional data suggesting a decrease in premature births among women who received the vaccine within the approved dosing time frame.
As a precaution, the FDA will include a warning not to administer the vaccine before 32 weeks of pregnancy due to the observed numerical imbalance in premature births.
Franny Strong Association CEO Veronica McNally, a member of the CDC's advisory committee, said on Friday that she "struggled" with making the recommendation.
"I struggled with this recommendation today for the reason that I don't know what the counseling looks like for the mother who asks her OB if she should get this vaccine, and the mother who would ask the child's pediatrician what she should do," she said.
The CDC has also required Pfizer to conduct post-marketing studies to further evaluate the risk of premature births and pregnancy-related complications following vaccination, such as eclampsia.
To facilitate ongoing monitoring of the vaccine's safety, Pfizer will launch a pregnancy registry, allowing women and obstetricians to report any adverse events after vaccine administration.