US FDA staff say COVID-19 vaccines being developed and manufactured for the 2023-2024 campaign should target one of the currently dominant XBB variants.
According to data collected by the Centers for Disease Control and Prevention, the XBB sublineage of the virus is now responsible for most cases in the United States. Existing COVID-19 vaccines also target the XBB subvariants, and it’s expected that this year’s updates will be more effective than last year’s bivalent shots in preventing the most severe forms of the virus.
However, these vaccines may not protect against the most recent XBB Omicron variant and its recent subvariants. As a result, the FDA is expected to issue an emergency authorization (EUA) for a new bivalent vaccine later this week.
That EUA will be based on relevant safety and effectiveness data from participants who received an earlier version of the recommended bivalent vaccine and pre-clinical animal data supporting its efficacy. In addition, the new vaccine will be approved based on the evidence that its antigens are more closely matched to circulating variants than those contained in the original bivalent vaccine.
This is the first time the FDA has issued an EUA for a bivalent COVID-19 vaccine. Previously, all vaccines approved for use in the United States were monovalent, containing only one strain of the virus.
While the federal Public Health Emergency declaration has expired, the threat of severe and potentially deadly COVID-19 infections persists. Experts advise that everyone six months of age and older get vaccinated. The best defense against the virus combines vaccination, essential hygiene habits, and following the CDC’s vaccination guidelines.
Vaccine makers Pfizer/BioNtech (PFE.N), Moderna Inc (MRNA.O), and Novavax Inc (NVAX.O) are developing versions of their vaccines to target XBB variants like Omicron. They are also expected to update their shots once the upcoming U.S. government-backed panel of outside experts selects the strain composition for the next COVID-19 campaign.
The committee is expected to recommend that the updated COVID-19 booster contain the XBB.1.5, XBB.1.16, and XBB.2.3 strains of the virus. Those strains are collectively the most prevalent in the United States, the agency’s reviewers said on Monday. The XBB sublineages of the virus are considered some of the most immune-evasive variants to date, and their presence is why many scientists believe that an updated Covid-19 vaccine should target these strains in particular.
The decision on what strain an updated COVID-19 booster should target will be announced on Thursday at a panel of FDA’s independent experts meeting. The panel will review all the available vaccine evidence, including studies of their performance against the current crop of circulating variants. The committee could also make recommendations for simplifying the immunization schedule and allowing two doses of the Moderna vaccine series for young children, a single Moderna dose for adults 65 or older, and individuals with compromised immunity.