A riddle wrapped in mystery inside an enigma

Omicron—and related travel restrictions—are spreading faster than virologists can determine how the new strain's mutations manifest.

There isn’t much more to know yet about Omicron—other than how rapidly it’s spreading. The virus has now been found in arrivals to 20 nations (though not yet in the United States) and now appears to have been detected in the Netherlands several days before South Africa announced its discovery of the new strain of Covid-19. Worse, passengers arriving in …