The U.S. recorded its first confirmed case of the omicron variant Wednesday — in a vaccinated traveler who returned to California after a trip to South Africa — as scientists around the world race to establish whether the new, mutant version of the coronavirus is more dangerous than previous ones. Dr. Anthony Fauci … announced the finding at the White House. … The infected person was identified as a traveler who had returned from South Africa on Nov. 22, developed mild symptoms and tested positive for COVID-19 Monday.