US halves Covid isolation time to five days for asymptomatic infections

Asymptomatic Americans who test positive for Covid-19 will have their self-isolation period cut from 10 to five days.

The isolation period starts from the day of the positive test.

Those who have been in close contact with someone who tested positive can also leave isolation after five days of being alerted, the US' Centers for Disease Control and Prevention (CDC) announced on Monday.

People can only leave isolation if they have no symptoms and must wear a mask everywhere - even at home around others - for at least five more days.

The CDC said the guidance comes with growing evidence that Covid-19 is most infectious in the two days before and three days after symptoms appear.

The decision was made amid a surge of cases of the Omicron variant of Covid, which is threatens to put pressure on hospitals and businesses.

CDC Director Rochelle Walensky said the country said: "Not all of those cases are going to be severe. In fact many are going to be asymptomatic.

“We want to make sure there is a mechanism by which we can safely continue to keep society functioning while following the science."

US officials had previously eased isolation rules for health care workers, from 10 to seven days.

New guidance also suggests close contacts who have had booster vaccines can skip quarantine if they wear masks in all settings for at least 10 days. Previously, people with two doses could skip quarantine.

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An expert said the new guidance on isolation time means there will be a significant number of Americans who are contagious but not isolating.

Dr Aaron Glatt, a New York physician who is a spokesman for the Infectious Diseases Society of America, said when people get infected, the risk of spread drops substantially after five days, but it does not disappear for everyone.

He said: “If you decrease it to five days, you're still going to have a small but significant number of people who are contagious."

He explained that is why wearing masks is a critical part of the CDC guidance.

Just before Christmas, the UK government announced vaccinated people who test positive for Covid-19 in England will be able to cut their isolation period from 10 to seven days if they return negative lateral flow tests.