Taking an act-now-ask-questions-later approach, countries around the world slammed their doors shut again to try to keep the new omicron variant at bay Monday as more cases of the mutant coronavirus emerged and scientists raced to figure out just how dangerous it might be.Taking an act-now-ask-questions-later approach, countries around the world slammed their doors shut again to try to keep the new omicron variant at bay Monday as more cases of the mutant coronavirus emerged and scientists raced to figure out just how dangerous it might be.