By LAURA UNGAR
AP Science Writer
Scientists warn that omicron’s whirlwind spread across the globe practically ensures it won’t be the last worrisome coronavirus variant. Every infection provides a chance for the virus to mutate, and research shows that omicron is at least twice as contagious as delta and at least four times as contagious as the original version of the virus. That means more people in whom the virus can further evolve. Experts don’t know how the next variants might shape the pandemic, and they say there’s no guarantee the sequels of omicron will cause milder illness or that existing vaccines will work against them. So they urge wider vaccination now while today’s shots are still effective.