COVID-19 variant XFG accounted for 0% of U.S. cases in May. By late-June, it became the third-most common strain.

A new strain of Covid, with an apparently telltale symptom, has reached the UK, and already accounts for a high proportion of new recorded cases in England. The arrival of the Stratus strain comes as ...

WASHINGTON (AP) — Flu is rising rapidly across the U.S., driven by a new variant of the virus — and cases are expected to keep growing with holiday travel. That variant, known as “subclade K,” led to ...

Add Yahoo as a preferred source to see more of our stories on Google. Getty Images An alleged warning has spread online for years about a supposed "new COVID-Omicron XBB variant" — a new strain of the ...

Massachusetts could be headed for a sharp uptick in flu cases in the coming weeks, public health experts warn, as a newly mutated strain is surging in the United Kingdom and appears to be only a ...

A new form of the flu, which is highly contagious and aggressive, is sweeping the nation this season. A mutation of influenza A H3N2, called subclade K, has been detected as the culprit in rising ...