Almost 988,000 new covid cases were reported on average worldwide between December 22 and 29. Several countries numbers at an all-time high during the previous 24 hours, including Argentina, Australia, Bolivia, the United States and many nations in Europe. The Omicron variant sprinted out of control as governments try to contain its spread without paralysing fragile economies.

Though research shows Omicron is less deadly than some previous variants, the number of cases could overwhelm hospitals in some countries.

Many countries, to reduce the economic impact of keeping workers at home, were considering shortening the period required for isolation after a positive COVID test or exposure.

Spain said on Wednesday it was reducing the quarantine period to seven days from 10, while Italy said it was planning to relax isolation rules for those who came into close contact with sufferers of the virus. U.S. health authorities released new guidance shortening the isolation period for people with a confirmed infection to five days from 10, so long as they are asymptomatic. South Africa also recalled rules that no longer required people without symptoms of COVID-19 to isolate or test if they have been in contact with a positive case, the government announced on Tuesday.

"I am highly concerned that Omicron, being highly transmissible and spreading at the same time as Delta, is leading to a tsunami of cases," WHO Director-General Tedros Adhanom Ghebreyesus told a news briefing. He warned it was the "twin threat" of the two variants that was behind the overall case load. "This is and will continue to put immense pressure on exhausted health workers, and health systems on the brink of collapse," the WHO chief added.

Many nations witnessed rise in cases. France was seeing a "dizzying" rise in cases, with 208,000 reported in the space of 24 hours - a national and European record. Every second, two people in France are testing positive for COVID-19, Health Minister Olivier Veran said, adding that the situation in hospitals was worrying because of the Delta variant, with Omicron yet to have an impact.

Italy, Spain, Portugal, Greece, Cyprus and Malta all registered record numbers of new cases on Tuesday.

Britain reported 183,037 COVID-19 cases on Wednesday, a new record and over 50,000 more than the previous high registered just a day earlier, government statistics showed. Ireland, too, reported record cases on Wednesday, with more than 16,000 new infections.

Australia registered almost 18,300 new cases, eclipsing Tuesday's previous pandemic high of around 11,300.

China stuck to its policy of zero tolerance, keeping 13 million people in Xian, capital of central Shaanxi province, under rigid lockdown for a seventh day with 151 new cases on Tuesday, reportedly none with the Omicron variant.

Doctors in India are bracing for a potential third wave driven by the highly contagious Omicron variant, as cases rise and political leaders hold mass gatherings ahead of key elections. In the past week, India's Omicron case numbers have more than tripled, with 781 infections now recorded, compared to 236 last Tuesday.

The federal Health Ministry warned last week of "initial signs of a surge in cases of Covid-19," with researchers at the Indian Institute of Technology projecting a third wave could peak between late winter and early spring. And from early January, India will start vaccinating children ages 15 to 18, as well as distributing booster shots for priority groups such as health care workers and the elderly.

In India the risk of the virus spreading rapidly is compounded by the fact that many people have stopped wearing face masks, are getting tested less frequently than before, and are congregating in large numbers. In an address to the nation on Saturday, the Prime Minister warned Indians to exercise precautions but not to panic as the new variant spreads.
-with inputs from CNN, Reuters, BBC