By ZEKE MILLER, OLGA R. RODRIGUEZ and MICHAEL BALSAMO
SAN FRANCISCO (AP) — The U.S. identified its first known case of the omicron variant Wednesday — in a vaccinated traveler returning to California from South Africa — as scientists around the world raced to establish whether the new, mutant version of the coronavirus is more dangerous than the previous ones. The first U.S. case is a person who returned from South Africa on Nov. 22. The person had mild symptoms that are improving, and has agreed to remain in quarantine. All the individual’s close contacts have been contacted and have tested negative. Nigeria and Saudi Arabia also reported omicron infections Wednesday, marking the first known cases in West Africa and the Persian Gulf region.