US shortens Covid-19 quarantine advice from 14 days to 'easier' 10

US health officials on Wednesday recommended a shortened quarantine period for people exposed to Covid-19, from 14 to 10 days if they haven't taken a test and have not developed symptoms.

This can be further reduced to just seven days if the exposed person receives a negative test, Centers for Disease Control and Prevention (CDC) scientist Henry Walke said.

"Reducing the length of quarantine may make it easier for people to take this critical public health action, reducing the economic hardship associated with a longer period, especially if they cannot work during that time," he said.

15 countries with the highest number of cases, deaths due to the Covid-19 pandemic

"We believe that if we can reduce the burden a little bit, accepting that it comes at a small cost, we may get a greater compliance overall."

The US is seeing more than 150,000 new cases a day and is bracing for a coronavirus super-surge following extensive travel over the Thanksgiving holiday.

The new guidance, which will be posted on the CDC's website and passed on to state and other local jurisdictions, was based on the latest research regarding infectiousness and how the disease progresses.

But, Walke stressed, it isn't risk-free and people who end quarantine early should continue to monitor for symptoms for the full 14 days.

Reducing the quarantine period from 14 to 10 days comes with a "residual risk" the person leaving early could transmit to someone else at between 1-12 per cent, according to CDC calculations.

CORONAVIRUS SPECIAL COVERAGE ONLY ON DH

For the seven-day quarantine with a negative test, the residual risk of onward transmission is 5-10 per cent.

In addition, the CDC also announced testing guidance in light of Thanksgiving travel and in anticipation of more of the same over the Christmas holiday period.

CDC epidemiologist Cindy Friedman stressed that the safest option was to postpone all plans.

But if people do decide to travel, the agency recommends they get a viral test one to three days before their trip, and consider getting tested after their trip within three to five days.

This should be accompanied by reducing non-essential activities for a full seven days after travel, even if the test is negative.

"Testing does not eliminate all risks, but when it's combined with reducing non-essential activities, symptom screening, other precautions such as wearing masks and social distancing, it can make travel safer," she said.