Daily COVID-19 infections have hit record highs in the United States, swathes of Europe and Australia as the new Omicron variant of the virus races out of control, keeping workers at home and overwhelming testing centres.
Almost two years after China first reported a cluster of "viral pneumonia" cases in the city of Wuhan, the regularly mutating coronavirus is wreaking havoc in many parts of the world, forcing governments to rethink quarantine and test rules.
Although some studies have suggested the Omicron variant is less deadly than some of its predecessors, the huge numbers of people testing positive mean that hospitals in some countries might soon be overwhelmed, while businesses might struggle to carry on operating because of workers having to quarantine.
France, Britain, Italy, Spain, Portugal, Greece and Malta all registered a record number of new cases on Tuesday.
The average number of daily COVID-19 cases in the United States has also hit a record high over the past seven days, according to a Reuters tally. The previous peak was in January of this year.
New daily infections in Australia spiked to nearly 18,300, on Wednesday eclipsing the previous pandemic high of around 11,300 hit a day earlier.
Australian Prime Minister Scott Morrison said his country needed "a gear change" to manage overburdened laboratories, with long walk-in and drive-in queues reported in a number of areas.
Testing bottlenecks have also built in European nations, including Spain where demand for free COVID-19 testing kits provided by Madrid's regional government far outstripped supply on Tuesday, with long queues forming outside pharmacies.
A number of governments were also increasingly worried by the huge numbers of people being forced into self-isolation because they had been in contact with a coronavirus sufferer.
"We just can't have everybody just being taken out of circulation because they just happen to be at a particular place at a particular time," Mr Morrison told reporters.
Italy was expected to relax some of its quarantine rules on Wednesday over fears the country will soon grind to a halt given how many people are having to self-isolate protectively, with cases doubling on Tuesday from a day earlier to 78,313.
However, China showed no let up in its policy of zero tolerance to outbreaks, keeping 13 million people in the city of Xian under rigid lockdown for a seventh day as new COVID-19 infections persisted, with 151 cases reported on Tuesday.
"I just want to go home," said a 32-year-old mechanic, who was in Xian last week for a business trip when the city was effectively shut off from the outside world.
No cases of Omicron have been announced in Xian so far.
Many countries are still grappling with the earlier Delta variant, including Poland, which reported 794 COVID-related deaths on Wednesday - the highest number in the fourth wave of the pandemic.
Deputy Health Minister Waldemar Kraska said more than 75 per cent of those who died were unvaccinated.
Early data from Britain, South Africa and Denmark suggests there is a reduced risk of hospitalisation for the Omicron compared with the Delta variant, the World Health Organisation said in its latest epidemiological report released overnight.
However, the report said further data was needed to understand how severity of illness may be impacted by vaccination and, or, prior infection.
The surge in cases is coinciding with the New Year holidays, normally a period of parties and travel. Some countries, such as Italy, have cancelled public celebrations, while authorities in Japan urged residents to keep end-of-year gatherings small.
"The highest risk is meeting people without taking adequate measures to prevent infection," said Norio Ohmagari, director of the Disease Control and Prevention Centre and a top health advisor to the Tokyo Metropolitan Government.