Despite low COVID cases in the U.S., vaccine experts are already preparing for winter to prevent a seasonal surge.
FDA Panel Recommend Updating COVID Vaccines
On Wednesday, a Food and Drug Administration advisory panel collectively recommended updating the COVID vaccines for the fall to target the highly contagious JN.1 variant or one of its descendants.
JN.1 arose in the U.S. in late August and became a powerful strain by January.
Various offshoots of JN.1, including the FLiRT variants KP.1.1 and KP.2, soon followed. By mid-May, KP.2 had overtaken JN.1 as the dominant strain, now accounting for over 25% of new cases, according to the Centers for Disease Control and Prevention (CDC).
Natalie Thornburg, a research microbiologist at the CDC, noted at Wednesday's meeting that the coronavirus appears to follow a consistent pattern: a dominant "parent" strain takes hold in early winter, and by spring, several descendants emerge. She cited the example of the XBB strain last year, which dominated in winter but gave rise to offshoots in spring.
The panel's recommendation did not specify whether to include the JN.1 strain or one of its descendants, but most members favored JN.1.
During a discussion following the vote, Dr. Bruce Gellin, a panel member and the chief of global public health strategy at the Rockefeller Foundation, remarked, "The trunk of the tree is probably our best bet for now."
Dr. Peter Marks, the FDA's top vaccine regulator, boosted the committee to contemplate a more current strain, such as KP.2.
Marks stated that we are paying a significant premium for mRNA vaccines to ensure they are the most current. He also emphasized the rapid development and production of new mRNA-based vaccine shots.
"Will we regret not having been a little bit closer?" he added.
FDA To Decide Soon Which Strain to Recommend for Vaccine Update
The FDA is expected to make a final decision soon on which strain to advise drugmakers to target. This action is set to start producing updated vaccines for the fall vaccination campaign.
Pfizer announced Wednesday it could have updated Covid shots available "immediately upon approval" from the FDA; Moderna said it could have shots ready for distribution by mid-August. Novavax says that it can manufacture an updated JN.1 vaccine, which will be ready by August.
However, if the FDA selects a different strain, the company will not have an updated shot ready for the fall campaign, as its protein-based vaccine takes longer to manufacture than the mRNA-based vaccines from Pfizer and Moderna.
All three drugmakers presented data on Wednesday showing that a JN.1 vaccine would generate higher antibody levels against circulating strains compared to the current vaccine, which targets XBB.1.5, a subvariant no longer in circulation. The older vaccine will be canceled once the modified one is accessible.
COVID hospitalizations have remained at their minimum levels since the pandemic started in 2020, though there are symptoms that cases may be beginning to rise.
According to CDC data, the weekly test positivity rate was 4.2% as of May 25, an increase from 3.4% the week before. In early 2022, during the fast transmission of the omicron variant, the weekly test positivity rate was around 30%.
Thornburg noted that virtually all Americans have developed some immunity to Covid, either through infection, vaccination, or both.
"We're sitting at about just below 100% seroprevalence," she said, citing the proportion of people exposed to the virus.
Later this month, a CDC advisory group will give approvals on who should get the vaccine in the fall.
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