More than nine million people have contracted the novel coronavirus since it was discovered in December.
As the World Health Organisation head Tedros Adhanom Ghebreyesus said that Sunday's was the highest single-day tally of new cases to date, he warned that the world was entering the most dangerous phase yet.
The speed at which cases emerged was increasing.
“The Covid-19 pandemic has demonstrated that, indeed, the world was not prepared,” Mr Tedros said on Monday. “Globally, the pandemic is still accelerating.”
The first case was reported in China in early January, and it took until mid-May to reach 4.5 million cases. In the five weeks since May 16, the number of worldwide cases has doubled. More than 1 million new cases were recorded in the past seven days.
While some of that reflected countries' improved testing and screening, it was believed to be a fraction of the true global number, with potentially millions of people going untested and cases unconfirmed.
While Europe and the United States still account for nearly half the now nine million cases, India and Brazil are surging up the scale of the outbreak as they struggle to contain cases.
India on Sunday recorded nearly 15,500 new cases – up nearly 1,000 on the day before, which itself was up 1,000 from Friday.
Global deaths stand at more than 471,000 and have doubled in seven weeks.
In terms of most deaths, the US leads the way with 122,300, followed by Brazil with 50,700 and the UK with 42,700.
China, which had brought cases down to near zero, is also trying to contain another outbreak in Beijing. But the government said it had a capacity to test more than a million people a day in the city alone.
Germany, hailed as a success story for effectively and aggressively tracing every case and for keeping a fatality rate well below the international average before reopening parts of the economy, reported a spike in infections above the rates needed for long-term containment.
Australia, too, was battling new cases in until now largely spared Victoria.
There were, however, bright spots such as Spain, which was reopening its borders, the death rates in former hot spot Italy have plunged, and Greece is set to admit foreign tourists again.
However, Mr Tedros warned against complacency, saying on Monday: "None of us are safe until all of us are safe. This is a lesson we must learn anew."
Just under half of all reported cases have recovered, although the number was likely to be higher as some countries do not report the statistic.
Mr Tedros urged world leaders not to politicise the pandemic but unite to fight it, reminding everyone that the outbreak was still accelerating and producing record daily increases in infections.
“The greatest threat we face now is not the virus itself, it’s the lack of global solidarity and global leadership,” he said. “We cannot defeat this pandemic with a divided world.”
Speaking later in the conference, WHO special envoy on Covid-19, Dr David Nabarro, said he believed it would be “two-and-a-half years until there will be a vaccine for everybody in the world”.
“Even if there’s a candidate by the end of the year, the safety and efficacy tests will take some time,” the British physician said. “And then the effort has to be put into producing large amounts of the vaccine so everyone in the world can get it and then organising the vaccination programmes.”
He added: “I would love it to be proved wrong.”
Additional reporting by agencies
