The U.S. Food and Drug Administration (FDA) has expanded its emergency use authorizations (EUAs) for the Pfizer and Moderna bivalent vaccines, opening the door for additional booster shots for certain vulnerable groups. These groups include individuals aged 65 and over and those with compromised immune systems. The changes are meant to prepare for the upcoming fall vaccination drive.
The bivalent vaccines, which have been available in the U.S. since September, provide protection against both the original strain of Covid-19 and the Omicron variant. Despite their availability, the EUAs placed heavy restrictions on how these vaccines could be administered. The recent changes by the FDA will allow certain individuals to receive an extra dose ahead of the general population.
Specifically, adults aged 65 and older who have already received one dose of the bivalent vaccine can get an additional shot four months after their first dose. Similarly, immunocompromised individuals who have received their first dose can get a second dose two months later. Additional doses may be provided based on the discretion of their healthcare provider.
Dr. Peter Hotez, co-director of the Center for Vaccine Development at Texas Children’s Hospital, has been urging the FDA to widen access to bivalent boosters. He generally supports the agency’s new guidelines but questions the age cutoff of 65. He suggests that the limit should be lowered to 60 or even 50.
The FDA also updated its guidelines for unvaccinated individuals. Now, most unvaccinated people can receive a single dose of a bivalent vaccine instead of multiple doses of the original single-strain vaccines. This change is due to most Americans having some level of immunity against Covid-19, either from vaccination or past infection.
In children, those aged six months to four years with compromised immune systems can receive additional doses of the bivalent vaccine, depending on what vaccine they previously received. Unvaccinated children in the same age range can now start with a two-dose series of the Moderna bivalent vaccine or a three-dose series of the Pfizer-BioNTech bivalent vaccine.
The FDA emphasized that most individuals who have received one dose of a bivalent vaccine are currently not eligible for a second dose and encouraged those who haven't yet received their first dose to do so. Currently, less than 20% of eligible individuals in the U.S. have received a recommended dose.
As the effectiveness of the bivalent vaccines begins to wane, many older adults and those with underlying health conditions have started questioning the need for an additional dose. The updated EUAs now allow the Centers for Disease Control and Prevention (CDC) and its Advisory Committee on Immunization Practices to recommend additional doses. A meeting is scheduled to discuss these changes and potentially endorse the FDA's modifications.
The FDA plans to make further decisions on future vaccinations after receiving advisory committee recommendations on the fall strain composition in June. Other countries, including Canada and the United Kingdom, have already begun offering another round of bivalent boosters to those at the highest risk from Covid-19 this spring.