The World Health Organization on Wednesday reported the largest single-day increase in coronavirus cases, as US President Donald Trump proposed hosting world leaders for the annual G7 summit as a sign of "normalization."
Trump, who is seeking to revive the battered US economy and his political fortunes ahead of the November election, again lashed out again at China, saying its "incompetence" was responsible for "this mass Worldwide killing."
The WHO, another frequent Trump target, said that 106,662 virus cases reported to the UN agency on Tuesday -- the most in a single day since the outbreak erupted in the Chinese city of Wuhan in December.
As the global death toll topped 325,000 and the number of cases neared five million, WHO chief Tedros Adhanom Ghebreyesus said he was "very concerned" about the situation in low- and middle-income nations.
As the number of cases rises, and the United States added more than 1,500 deaths in the past 24 hours, Trump said the country was "Transitioning back to Greatness" and he may host the G7 summit in June at Camp David.
"I am considering rescheduling the G-7, on the same or similar date, in Washington, D.C., at the legendary Camp David," he said on Twitter.
"The other members are also beginning their COMEBACK. It would be a great sign to all -- normalization!"
White House spokeswoman Kayleigh McEnany said a face-to-face summit, rather than one by videoconference as had been planned, would be a "show of strength and optimism."
G7 countries -- Britain, Canada, France, Germany, Italy, Japan and the United States -- take turns organizing the annual gathering.
French President Emmanuel Macron's office said he would attend the summit if "health conditions allow."
German Chancellor Angela Merkel said she would "wait and see what happens."
- Promising studies -
There was encouraging news on the scientific front Wednesday, as two studies on monkeys offered hope that humans can develop protective immunity to the virus.
Researchers reported progress from one study which looked at a prototype vaccine, and another on whether infection with COVID-19 provides immunity against re-exposure.
"We demonstrate in rhesus macaques that prototype vaccines protected against SARS-CoV-2 infection and that SARS-CoV-2 infection protected against re-exposure," said senior author Dan Barouch of the Beth Israel Deaconess Medical Center in Boston.
Many governments see the development of an effective vaccine as the only surefire way to fully reopen their economies without risking increased death tolls.
Latin America has seen infections surge and, in some cases, countries have reinstated lockdown measures that had been eased.
Brazil has been hardest hit, rising to the third-highest number of cases in the world. Peru, Mexico and Chile have also seen steady increases in infections.
Health officials in Brazil reported 1,179 new coronavirus deaths on Tuesday, the first time the daily toll exceeded 1,000, but far-right President Jair Bolsonaro remains bitterly opposed to lockdowns, having described them as unnecessary over a "little flu."
With the outbreak in the world's sixth-largest country expected to accelerate until early June, Bolsonaro has refused to accept experts' advice, pressing regional governors to end stay-at-home measures.
And like Trump, he has promoted the use of anti-malaria drugs against the virus despite studies showing they have no benefit and could have dangerous side effects.
There are worrying signs in Argentina too, with authorities in Cordoba having to backtrack on easing lockdown measures following a sharp spike in infections.
Peru saw its case count shoot past 100,000 and deaths top 3,000.
- Europe hopes to save tourism -
Europe is meanwhile hoping the worst is behind it, with the number of new cases and deaths on a steady decline.
The global death toll now stands at more than 325,000. More than 93,400 deaths have occurred in the United States, the hardest-hit country, according to Johns Hopkins University.
Lockdown measures are being eased in many parts of Europe, with residents enjoying some of their old freedoms.
"I haven't seen the sea for two months," said Helena Prades at a beach in Barcelona. "We just really wanted to hear the sound of the waves."
As Spain emerges from one of the world's toughest lockdowns, face masks are now mandatory for anyone aged six and over in public where social distancing is not possible.
European officials are scrambling to try to save the summer tourism season, which is crucial for the continent's economies.
European Union tourism ministers held a virtual meeting on Wednesday as Greece announced plans to restart its travel season.
Prime Minister Kyriakos Mitsotakis said seasonal hotels could reopen from June 15 and international flights would resume from July 1.
In Italy, airports were given the green light to reopen from June 3, including for international flights.
- Gradual reopening in Asia -
Countries in Asia have also been gradually reopening, with South Korean students lining up for temperature checks and given hand sanitizer as they returned to school after two months off.
And India said domestic air travel will resume on May 25 after a two-month shutdown, even as the world's second-most populous country reported its biggest daily jump in coronavirus infections, with 5,611 new cases in 24 hours.
Nearly 107,000 cases have been reported in India and more than 3,300 people have died, with experts predicting that infections will peak in June-July.