KP.3 Variant Now Leads Nationwide COVID-19 Cases
The new KP.3 variant has surged to account for 25% of new COVID-19 cases across the U.S., becoming the dominant strain, according to the Centers for Disease Control and Prevention (CDC). This rise coincides with a general uptick in key virus spread metrics that the CDC is monitoring.
Rising metrics and regional increases
The CDC’s wastewater surveillance data indicates accelerating virus levels in the West. Emergency room visits for COVID-19 have also increased slightly for all age groups. The CDC estimates that COVID-19 infections are growing in 30 states and territories.
Similarity to previous strains
KP.3 has overtaken the KP.2 variant, which previously led in case numbers but now represents 22.5% of cases. Both variants are “very, very similar” to the JN.1 variant that dominated last winter’s infections. Natalie Thornburg, chief lab official at the CDC’s Coronavirus and Other Respiratory Viruses Division, highlighted that KP.3 has slight differences from KP.2, potentially making it better at evading immunity.
Vaccine updates and decisions
As KP.3 ascends, the FDA has opted to update fall vaccines for the JN.1 variant, despite considering a newer formula targeting KP.2. Moderna’s animal studies suggested its KP.2-targeted shot offered similar protection against current variants. Pfizer’s shot for KP.2 showed better antibody responses for JN.1 variants, including KP.3. However, the FDA decided against the KP.2 shots, with advisors expressing concern about their ability to broaden immunity for future strains.
The decision underscores the challenges in staying ahead of rapidly evolving variants and highlights the ongoing efforts to adapt vaccines to provide the most effective protection. As the situation evolves, public health authorities continue to monitor and respond to these changes to manage the pandemic effectively.