CDC: people who test positive for Covid with no symptoms should isolate just five days

US health authorities have halved, to five days, the recommended isolation time for people with asymptomatic Covid.

The US is facing a huge surge in Covid cases, driven by the Omicron variant, which contributed to travel chaos over Christmas and stoked worries about damage to the economy and education.

The CDC said that after isolation, asymptomatic people should wear a mask around others for another five days.

It also recommended a five-day quarantine for those exposed while unvaccinated, more than six months out from their second dose or more than two months out from a single-dose Johnson & Johnson shot and not yet boosted.

Others pointed to the need to avoid significant disruption to daily life.

Amid cancellations caused in part by Omicron, Anthony Fauci said a mandate might confer stronger protection on flights, for which federal regulations require all those aged two and older to wear a mask.

Two officials told the Associated Press advisers had yet to make a recommendation, as a mandate could trigger logistical and legal concerns.