The daily business briefing: December 6, 2021

New travel restrictions take effect Monday for people entering the United States. As part of the Biden administration's response to the new Omicron coronavirus variant, the Centers for Disease Control and Prevention has shortened the window for a pre-departure coronavirus test, with all passengers now required to show a negative result from a test conducted within 24 hours of their flight to the U.S. Previously, vaccinated travelers could get a test any time within three days of departure, although the 24-hour rule already applied to unvaccinated travelers. The narrower window will "provide less opportunity to develop an infection with the Omicron variant prior to arrival in the United States," according to the updated CDC order. U.S. airlines also have been asked to collect contact-tracing information for arriving passengers.

Bitcoin plunged by as much as 20 percent over the weekend before regaining some of the lost ground on Sunday. The price of Ether, the second-largest cryptocurrency, fell by more than 15 percent before climbing back Sunday close to where it started the weekend. The volatility came after last week's stock-market selloff, as investors sought safer investments due to rising concerns about fallout from the spread of the new Omicron coronavirus variant. Other cryptocurrencies also struggled. Cryptocurrencies are notoriously volatile. In addition to uneasiness over Omicron, the Federal Reserve's suggestion that it could unwind its economy-boosting asset purchases faster to fight high inflation also might have sparked some selling.

U.S. stock index futures were mixed early Monday after last week's losses. Futures tied to the Dow Jones Industrial Average and the S&P 500 were up by 0.6 percent and 0.3 percent, respectively, at 7 a.m. ET. Futures for the tech-heavy Nasdaq were down by 0.3 percent. The Dow and S&P 500 dropped by 0.2 percent and 0.8 percent, respectively, on Friday, as investors reacted to fears of economic fallout to the new Omicron coronavirus variant and the Federal Reserve's plan to speed up policy tightening to fight high inflation. The Nasdaq plunged by 1.9 percent. Slower-than-expected job growth contributed to the selling. The Labor Department reported that employers added 210,000 jobs last month, well below the 573,000 economists surveyed by Dow Jones expected.

The Biden administration plans to fast-track authorization of COVID-19 vaccines tweaked to fight the Omicron coronavirus variant, which federal regulators said Sunday had been detected in 16 states. Food and Drug Administration officials have met with vaccine makers to start hammering out guidelines for data that will be needed to expedite approval of changes to current vaccines that will be necessary to make them sufficiently effective against the new strain. "The FDA will move swiftly and CDC will move swiftly after," Centers for Disease Control and Prevention Director Rochelle Walensky said on ABC's This Week with George Stephanopoulos. "We're every day hearing about more and more cases." Public health officials say Omicron appears to cause less severe illness than the widespread Delta variant, but concerns about its impact have roiled markets.

Shares of Chinese developer Evergrande plunged by 20 percent on Monday, hitting a record low as the company again approached default. Evergrande warned Friday that it might not have enough money to make looming debt payments, as its 30-day grace period ended and it faced interest payments totaling $82.5 million. As business hours closed in Asia, two bondholders said they had yet to receive payments due from Evergrande. The company declined to comment. Evergrande, once China's top-selling developer, has more than $300 billion in liabilities, and its potential collapse threatens to trigger further damage in China's real estate industry. China's central bank sought to reassure markets by cutting reserve requirements for banks as Beijing vowed to promote the property sector's health.