More people had Covid-19 diagnosed in the past seven days than in any other week since the start of the pandemic.
Infections topped 5.2 million globally, with the worst outbreaks accelerating in many countries that are ill-equipped to deal with them.
The worrisome trend comes days after the world passed three million deaths, with countries rushing to distribute vaccinations to get the virus under control.
There was a 12 per cent increase in infections this week, Johns Hopkins University said, casting doubt on the hope that the end of the pandemic is in sight.
The weekly increase passed the previous high set in mid-December.
While infection rates have largely slowed in the US and UK, countries in the developing world, particularly India and Brazil, have surging caseloads.
A leading epidemiologist at the World Health Organisation said on Monday that the latest rise in Covid-19 infections worldwide included increases among all age groups.
"We are seeing a slight age shift in some countries, driven by social mixing," Maria van Kerkhove told a WHO briefing.
The global death toll is also gaining momentum again.
Fatalities have increased for the past month and hit about 82,000 for the week ending April 18, an average of almost 12,000 a day.
That was up from a little more than 60,000 in the week ending March 14, or about 8,600 a day.
The world can bring the global Covid-19 pandemic under control in coming months provided it distributes the necessary resources fairly, the director general of the WHO said on Monday.
"We have the tools to bring this pandemic under control in a matter of months if we apply them consistently and equitably," Dr Tedros Adhanom Ghebreyesus said.
But Dr Tedros also expressed concern over the "alarming rate" at which Covid-19 was spreading in those aged between 25 and 59 worldwide, possibly caused by more contagious variants.
"It took nine months to reach one million deaths; four months to reach two million, and three months to reach three million," he said.
India and Brazil are the two largest contributors in driving up cases globally.
Facing a sudden surge in coronavirus infections, India is again home to the world's second-largest outbreak, overtaking Brazil, which moved ahead in March.
Hospitals from Mumbai to Sao Paulo are under increasing pressure as admissions continue to rise.
New variants of the virus have also sent infections surging further.
Brazil is where one of the most potentially deadly coronavirus mutations, the P1 variant, was identified in December.
Studies suggest these strains, along with variants first seen in South Africa and Britain, are more contagious.