Emerging Flu Variant Raises Concerns Amid Seasonal Influenza Trends in Florida

Flu is on the rise in much of Florida and across the U.S. Health care experts have noted a significant increase in flu-related illnesses this holiday season. All eyes are on a mutated form of the influenza A strain H3N2, known as clade K or subclade K, which has caused severe flu seasons in several countries and is contributing to many of the reported flu cases in the U.S.

Andrew Pekosz, co-director of the Johns Hopkins Center of Excellence in Influenza Research and Response, stated during an online news conference that this subclade K variant has mutations that may allow it to evade some of the vaccine-induced protections.

Reports indicate that flu and influenza-like illness remain elevated across Florida, although some areas, including Miami-Dade and Monroe counties, have seen a decline in cases. The Florida Department of Health reports that the predominant strain in the state is influenza A H3.

The CDC notes that as of December 12, Florida has reported sequences of subclade K this flu season. The 2025-2026 flu vaccine, formulated to protect against H1N1, A(H3N2), and a B/Victoria lineage virus, still offers some protection against the circulating subclade K variant.

Experts are urging that it is not too late to get vaccinated, emphasizing the importance of vaccination to reduce the risk of severe illness. As of the latest estimates, the CDC has reported approximately 2.9 million flu illnesses, 30,000 hospitalizations, and 1,200 deaths this season.

In terms of other respiratory illnesses, while flu activity is increasing, COVID-19 levels remain low nationally, and RSV activity appears to be rising, particularly among children under 4 years old. Recommendations for avoiding illness include good hygiene practices, vaccination, and monitoring symptoms closely.

Dr. Carlos Penaherrera from Baptist Health South Florida suggests that individuals should seek medical advice early if symptoms appear, particularly if accompanied by high fever or body aches. The flu season generally runs from October through May, and experts expect flu cases to rise as holiday travel increases.

The situation remains dynamic, and public health officials are closely monitoring the trends in influenza and other respiratory viruses across Florida and the nation.