Moderna and Pfizer win approval for KP.2 vaccine as KP.3 variants account for about half of current cases

The FDA has approved Moderna’s and Pfizer’s updated COVID-19 vaccines targeting the KP.2 variant, an offshoot of the Omicron strain that was dominant in the U.S. in May 2024. More recently, KP.3 variants are gaining ground. As of August 20, 2024, CDC Nowcast projections estimate KP.3.1.1 accounts for approximately 37% of new COVID-19 cases in the U.S. KP.3.1.1. and KP.3 jointly make up about 54% of cases. Meanwhile, KP.2’s descendant, KP.2.3, is responsible for about 14.4%. Another variant, LB.1, represents about 14% of cases.

A pre-print study found that the KP.3.1.1, a subvariant of the SARS-CoV-2 JN.1 variant exhibits higher relative effective reproduction numbers (Re) than other JN.1 sublineages in countries including the U.S., U.K., Spain, France, and Canada.

The CDC has advised everyone aged six months and older to receive the 2024-2025 COVID-19 vaccine. The updated vaccines are likely to be more effective than the current vaccines, which target XBB.1.5, a subvariant that is no longer circulating.

An evolving variant landscape and vaccine strategy

The approval and emergency use authorization for the vaccines covers a monovalent (single) component based on the KP.2 variant. This decision comes as the number of SARS-CoV-2 variants continues to diversify, but with JN.1 having emerged as the dominant strain of SARS-CoV-2 in late 2023, displacing previous XBB lineages whose offshoots included XBB.1.5 (dubbed “Kraken” in the media) and XBB.1.16 (“Arcturus”) that circulated primarily in 2023.

“Based on the further evolution of SARS-CoV-2 and a rise in cases of COVID-19, the [FDA] subsequently determined and advised manufacturers that the preferred JN.1-lineage for the COVID-19 vaccines (2024-2025 formula) is the KP.2 strain, if feasible,” the FDA noted in a press release.

KP.2 and KP.3 feature immune-evasive spike mutations nicknamed “FLiRT.” The KP.2 and KP.3 variants share many core mutations.

The FDA’s decision to target the KP.2 variant for the updated COVID-19 vaccines reflects a shift in strategy based on the evolving virus landscape. Initially, the agency recommended targeting the JN.1 lineage, but as KP.2-related variants gained prevalence, the agency opted for KP.2 owing to its close relationship to these emerging strains.

A surging COVID summer

This summer, COVID-19 cases have surged across the U.S.. The CDC reported an 18.1% test positivity rate for the week ending August 10, 2024, the highest since January 2022. Wastewater surveillance data indicates “very high” viral activity in 27 states. Positivity rates are potentially higher than reported. That said, the virus appears to have lost some of its ability to cause severe disease. Hospitalizations are up only slightly to 3.3 per 100,000 population for the week ending July 20, 2024, up from 3.2 the previous week. That said, deaths attributed to COVID-19 are also up modestly, accounting for 1.9% of all deaths in the U.S. for the week ending August 10, 2024, compared to 1.6% the previous week.

 

Data citations:

1. CDC COVID Data Tracker
2. Gangavarapu, K., Latif, A. A., Mullen, J. L., Alkuzweny, M., Hufbauer, E., Tsueng, G., Haag, E., Zeller, M., Aceves, C. M., Zaiets, K., Cano, M., Zhou, X., Qian, Z., Sattler, R., Matteson, N. L., Levy, J. I., Lee, R. T. C., Freitas, L., Maurer-Stroh, S., … Hughes, L. D. (2023). Outbreak.info genomic reports: scalable and dynamic surveillance of SARS-CoV-2 variants and mutations. Nature Methods. https://doi.org/10.1038/s41592-023-01769-3

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Filed Under: Infectious Disease
Tagged With: COVID-19 variants, FDA vaccine approval, KP.2 variant, pharma industry trends, SARS-CoV-2 evolution
 

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