this is the first confirmed case of covid-19 caused by the omicron variant detected in the united states. reporter: a fully vaccinated person, returning from south africa to san francisco, the first to test positive for the new variant about which it wille is known. have they had a booster shot yet? to my knowledge no. reporter: they returned to the united states on november 22nd and tested positive a week later, and is now isolating as close contacts are being traced and tested. all close contacts thus far have tested negative. reporter: the news coming as the cdc prepares to tighten testing restrictions on all travelers entering the united states shortening the time frame for a negative test from 72 hours to 24. this person, i mean, did what we hope other people would do. they got off and as soon as they became symptomatic, they went and got tested and it was positive. reporter: a mandatory quarantine not under consideration as dr. fauci is calling on the 100 millio
new variant. have they had a booster shot yet? to my knowledge no. reporter: they returned to the united states on november 22nd and tested positive a week later and isolating as close contacts are being traced and tested. all close contacts thus far have tested negative. reporter: the news coming as the cdc prepares to tighten testing restrictions on all travelers entering the united states shortening the time frame for a negative test from 72 hours to 24. this person, i mean, did what we hope other people would do. they got off and as soon as they became symptomatic, they went and got tested and it was positive. reporter: a mandatory quarantine not under consideration as dr. fauci is calling on the 100 million eligible americans who have yet to get boosted to do so. if you look at the peak following the third shot boost, it goes way up here. reporter: fauci warning not to wait for a omicron tailored booster shot. the mistake people make is to say let me wait and s
this is the first confirmed case of covid-19 caused by the omicron variant detected in the united states. reporter: a fully vaccinated person who recently returned from south africa to san francisco, the first to test positive for the new variant about which little is known. had they had a booster shot yet? to my knowledge, no. reporter: this person returned to the united states on november 22nd, tested positive a week later and is now isolating as close contacts are being traced and tested. all close contacts thus far have tested negative. reporter: the news coming as the cdc prepares to tighten testing restrictions on all travelers entering the united states. shortening the time frame for a negative test from 72 hours to 24. this person, i mean, did what we hope other people would do. they got off and as soon as they became symptomatic they went and got tested. reporter: a mandatory quarantine not currently under consideration as dr. fauci is calling on the 100 mill