A surge in COVID-19 cases in the United States and around the globe is sparking concern among health officials who are warning that more severe variants of the virus may be coming. “COVID-19 is still ...

The COVID-19 variant KP.3.1.1 rose 12.7% and now makes up over 50% of COVID cases, the CDC Nowcast data tracker shows.

Understanding this “checkerboard” pattern may help determine when best to get a COVID-19 vaccine booster, researchers said.

Epidemiologists have not yet identified exactly how a person in Missouri contracted bird flu last week, said the U.S. Centers ...