WASHINGTON—Hailing the exclusive gathering as an opportunity to usher in an era of peace and goodwill, Health Secretary Robert F. Kennedy Jr. hosted a lively meet-and-greet Thursday with a variety of ...

SARS-CoV-2 has been evolving the ability to evade the immune system about twice as fast as the fastest-evolving flu virus. It averages more than a dozen significant changes every year.

Here's what experts say is turning Southern California's speedy wildfires into a deadly urban conflagration that is defying the calendar.