A variant of HIV that is faster at progressing to serious illness and more contagious than other versions of the virus has been circulating in the Netherlands for decades, researchers have found. The ...

A global study has found strong evidence that a new form of the coronavirus has spread from Europe to the US. The new mutation makes the virus more likely to infect people but does not seem to make ...

A variant strain of the coronavirus, one that was first discovered in the United Kingdom, is now the dominant strain of the virus circulating throughout the United States, CDC Director Rochelle ...

Bird flu has always worried pandemic planners, but a new twist is raising the stakes: scientists are now tracking variants that can keep multiplying even when a human body turns up the heat. A strain ...

(CNN) — The United States may be heading into its second severe flu season in a row, driven by a mutated strain called subclade K that’s behind early surges in the United Kingdom, Canada and Japan.