Anticipating another layer of defense against respiratory syncytial virus (RSV), a prevailing cause of infant hospitalizations in the United States, expectant parents may soon have a fresh option to safeguard their newborns. The Food and Drug Administration (FDA) has announced its expansion of approval for Pfizer’s Abrysvo vaccine to encompass expectant mothers, a decision that could significantly impact newborn health.
This expanded approval entails that pregnant women receiving the vaccine can bestow immunity to their infants before birth, providing a protective shield during the initial months of their lives. The FDA’s Dr. Peter Marks, Director of the Center for Biologics Evaluation and Research, stated, “This approval provides an option for healthcare providers and pregnant individuals to protect infants from this potentially life-threatening disease.”
Pfizer’s newly granted approval follows a favorable assessment from the FDA’s external vaccine experts in May. The study showed that the vaccine exhibited 69.4% efficacy in diminishing the risk of severe lower respiratory tract illness in infants up to six months after birth.
Pending approval by the Centers for Disease Control and Prevention (CDC), the vaccine could be added to the roster of “maternal vaccines” recommended before childbirth. This move could substantially bolster the resilience of newborns during their initial, most susceptible months.
Annaliesa Anderson, Chief Scientific Officer of Vaccine Research and Development at Pfizer, expressed, “Today, a long-sought-after goal to deliver a maternal vaccine that will help protect infants six months of age or younger – when they are at greatest risk of possible serious consequences from RSV – has been achieved.”
Despite the fact that nearly all children experience at least one RSV infection by the age of two, the virus poses particularly grave risks for infants contracting their first bout of the disease during their earliest months.
Previously, the FDA had exclusively approved Pfizer’s Abrysvo vaccine for use in older adults. For individuals aged 60 and above, consulting their physicians about receiving the vaccine is recommended.
The CDC’s Advisory Committee on Immunization Practices must convene once more to assess updated recommendations for administering vaccines during pregnancy. While medical practitioners aren’t legally bound by the committee’s suggestions, they play a pivotal role in shaping insurance coverage requirements for vaccines.
Parallel to Pfizer’s Abrysvo, an alternative means of safeguarding infants from RSV has also emerged: nirsevimab, an antibody injection marketed as Beyfortus by Sanofi and AstraZeneca. The CDC has recently recommended parents to opt for the Beyfortus shot for babies entering their first RSV season in the upcoming fall and winter.
Intriguingly, both Abrysvo and Beyfortus have shown safety and efficacy in trials aimed at curbing RSV hospitalizations in infants, as indicated by a work group convened by the agency earlier this year.
However, balancing the cost-effectiveness of recommending both vaccines poses a challenge. Together, the combined cost of both vaccines per child is estimated at $700 before insurance coverage. As a consequence, the CDC might lean towards recommending Abrysvo as the primary option, while Beyfortus would serve as a backup for those with unique circumstances.
Complicating the issue further are a few rare instances of preterm births observed in babies of mothers who received Abrysvo during pregnancy. Although the data from Pfizer’s trial was not statistically significant, a larger increase in preterm births compelled GSK to halt a separate RSV vaccine trial in pregnant women earlier this year.
Despite ongoing discussions about the potential causal relationship, the FDA has mandated Pfizer to conduct post-marketing studies to assess the risk of preterm birth. A warning about the “numerical imbalance” will be incorporated, as the available data is deemed insufficient to establish or dismiss a direct connection between preterm birth and Abrysvo.
