<span style="color: #222222;">US health officials have halved the recommended isolation time for people with asymptomatic Covid-19 from 10 to five days, amid a surge in cases. The Centers for Disease Control (CDC) said this must be followed by five days of wearing a mask around others.<br />''<br />''It said most transmissions happened in the two days before and three days after symptoms develop. The measure is expected to alleviate disruptions caused by staff shortages in many areas because of infections.<br />''<br />''The sharp rise in cases has been fuelled by the Omicron variant of the virus, which is now dominant in the US. Early studies suggest Omicron is milder but more contagious than other variants.<br />''<br />''The growing number of people becoming infected and having to isolate has put pressure on several industries, including air travel, with thousands of flights cancelled during the Christmas holiday.<br />''<br />''Leaders of major US airlines were among those calling for the change, as cancellations continued for a fourth day on Tuesday.<br />''<br />''The CDC said the new recommendation was motivated by science, and the announcement came as more than 200,000 daily infections were confirmed in the past two days nationwide.<br />''<br />''CDC director Dr. Rochelle Walensky said the new guidance balances what we know about the spread of the virus and the protection provided by vaccination and booster doses. These s ensure people can safely continue their daily lives, Dr. Walensky said in a statement.</span><br />