Japan banned fans from the Olympic Games on Thursday as the Delta variant drove devastating Covid-19 outbreaks in parts of Asia-Pacific and Africa, and cases rose again in Europe and the United States.
Delta is the most infectious strain of the virus since the start of the global pandemic in early 2020.
Originally detected in India months ago, it has quickly spread and today is accelerating outbreaks even in countries with high vaccination rates. That led the World Health Organization to warn that the world was at a "perilous point" as the official global death toll passed four million.
Japan, where the strain currently accounts for around 30 percent of cases, on Thursday banned spectators from Olympic venues in Tokyo — where most competitions will take place.
Earlier, Prime Minister Yoshihide Suga announced that the capital will be under a state of emergency throughout the Games, until August 22, though far looser than the lockdowns seen in other parts of the world such as Australia.
The government there said Thursday it would rush 300,000 vaccine doses to Sydney as Australia's largest city — in its third week of lockdown — struggled to bring a Delta outbreak under control.
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South Korea, once considered a coronavirus response model along with Australia, reported nearly 1,300 new infections on Thursday, the highest since the pandemic began.
Elsewhere in Asia, Vietnam's Ho Chi Minh City has gone into lockdown. The virus threat also forced organisers Thursday to postpone the Southeast Asian Games that had been due to take place in Vietnam.
Indonesia has become a global Covid-19 hotspot with death rates rising tenfold in a month to more than 1,000 on Wednesday.
Hospitals in the vast archipelago of 270 million have been pushed to the brink by the flood of coronavirus cases.
The out-of-control virus surge has led to a run on ivermectin, an anti-parasite drug backed by leading politicians and social media influences as a "miracle cure" despite little evidence and health warnings.
Across the globe in Brazil, which has the world's second-highest known Covid-19 death toll after the US, authorities said Wednesday that the variant has started spreading rapidly in the country's most populous state Sao Paulo.
And in Africa, the WHO warned the worst was yet to come after the most disastrous week in its history of pandemics.
"Africa has just marked the continent's most dire pandemic week ever. But the worst is yet to come as the fast-moving third wave continues to gain speed and new ground," said Dr Matshidiso Moeti, the WHO's regional director for Africa.
And in Tunisia, authorities said the North African country's health system has "collapsed" under the weight of the pandemic, describing the current health situation as "catastrophic."
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The WHO announced Wednesday that more than four million people have died from Covid-19, but cautioned that the figure was an underestimate of the true toll.
"The world is at a perilous point in this pandemic," said the UN body's chief Tedros Adhanom Ghebreyesus, urging "extreme caution" and accusing rich countries of hoarding vaccines and of acting "as though the pandemic is already over".
Delta is making itself felt even in places where vaccination drives have been robust, like the United States and Europe.
France on Thursday advised its citizens against travelling to Spain and Portugal because of a Delta-caused spike in cases.
In Russia, where Delta has driven the death rate to pandemic highs recently among a vaccine-hesitant population, Moscow police have launched dozens of criminal probes to crack down on fake inoculation certificates.
And Delta-fuelled cases were also on the rise in the US, where a once-rapid immunisation campaign has dropped off steeply since April.
The seven-day average of new cases rose 21 percent compared with two weeks ago, Centers for Disease Control data showed Wednesday.
Regions in the Midwest and South with lower vaccination rates are experiencing higher case rates than regions with high vaccination rates such as the Northeast.
Amesh Adalja of the Johns Hopkins Center for Health Security told AFP that the likely trend now is that Covid-19 will be more of a problem in areas where vaccinations are low.
"In other parts of the country, the pandemic is largely going to be something that's managed as more of an ordinary respiratory virus."
One such area is New York City, where on Wednesday a ticker-tape parade honoured the essential worker "heroes" who kept the city running through the pandemic.