COVID vaccine makers will be advised to update their shots to target the KP.2 variant, an offshoot of the JN.1 variant that spread widely last winter, the U.S. Food and Drug Administration announced Thursday.

It’s a turnaround for the agency: The new recommendation follows an FDA advisory panel vote last week that unanimously recommended COVID vaccines target the older JN.1 variant this fall.  

Following that vote, panel members and Dr. Peter Marks, the agency’s top vaccine regulator, differed on which variant the agency should choose to target. Most panel members chose JN.1, while Marks preferred selecting a newer strain, such as KP.2.

“We are paying an incredibly high premium for mRNA vaccines to be able to have the freshest vaccines,” Marks said at the time.

Although the FDA said it first advised vaccine makers to target JN.1, the most current data, along with a recent rise in COVID cases, suggests the preferred variant for the updated vaccines to target is now the KP.2 strain, the FDA said.

“[The] FDA has communicated this change to the manufacturers of the licensed and authorized COVID-19 vaccines,” the agency added. “The agency does not anticipate that a change to KP.2 will delay the availability of the vaccines for the United States.”

JN.1 has largely fallen out of circulation in the United States, according to the U.S. Centers for Disease Control and Prevention. KP.2 now accounts for 22.5% of new COVID cases in this country while KP.3, a sister variant, is fueling 25% of new cases.

Three drugmakers produce COVID vaccines: Pfizer, Moderna and Novavax. Pfizer’s and Moderna’s vaccines are mRNA-based, while Novavax’s is protein-based. Because protein-based vaccines take much longer to manufacture, Novavax has indicated it won’t be able to make a KP.2 vaccine in time for the fall, NBC News reported. Instead, it plans to distribute a JN.1 vaccine, which it had already been producing.

The process of selecting the next round of COVID vaccines is falling into a routine that mimics how the annual flu shot is updated.

During the FDA advisory committee meeting, vaccine makers presented data showing that a JN.1 vaccine should generate higher levels of antibodies against circulating strains of the virus compared to the current vaccine, which targets XBB.1.5, a variant no longer in circulation. 

The FDA advisory committee did not recommend who should get the updated shots. That question will be tackled by the CDC, which is holding its own advisory committee meeting on vaccines later this month. 

More information

The CDC has more on COVID vaccines.

SOURCE: U.S. Food and Drug Administration, news release, June 13, 2024; NBC News

Source: HealthDay