India on Monday became the country with the third-highest Covid-19 caseload in the world, as a group of scientists said there was now overwhelming evidence that the disease can be airborne – and for far longer than originally thought.
With the globe's hardest hit nation, the United States, struggling to come to grips with the new normal of social distancing and mask-wearing, officials there warned that some of the country's hospitals were in danger of being overwhelmed by a surge in infections.
Despite signs of progress in parts of Europe – where the Louvre museum in Paris reopened Monday – total global infections surged past 11.5 million, with more than 535,000 deaths, since the pandemic first emerged in China late last year.
The Indian government, like many around the world, has gradually lifted virus restrictions to help the battered economy, but the number of cases has continued to climb – to over 720,000 on Tuesday (and over 20,000 deaths), with the total now greater than Russia.
India's major cities including New Delhi and Mumbai are suffering the most, and critics say not enough tests are being conducted – meaning that many Covid-19 infections are likely to go undiagnosed.
The surge has forced authorities in India to convert hotels, wedding halls, a spiritual centre and even railway coaches to help provide care to coronavirus patients.
And in Australia, where the virus outbreak had largely been brought under control, new outbreaks in Melbourne forced authorities to effectively seal off the state of Victoria from the rest of the country.
Around the world, governments are struggling to balance the need to reopen economies wrecked by weeks of lockdown measures against the risk of new infections as people return to normal life.
In Europe, the pandemic appears more under control, though officials have ordered new local lockdowns in Spain's northwestern Galicia and another northeastern town to curb fresh outbreaks.
The Louvre, the world's most visited museum, reopened with nearly a third of its galleries shut and crowding banned around the Mona Lisa and other masterpieces.
"It is very important that cultural establishments can welcome the public because we need it," said Arzel Bertrand, visiting from a town southeast of Paris.
"They need the public, too, to survive," he added.
Amid the reopenings came a stern warning from experts who said governments must recognise that coronavirus can spread through the air far beyond the two metres (six feet) urged in social distancing guidelines.
"There is significant potential for inhalation exposure to viruses in microscopic respiratory droplets at short to medium distances (up to several metres, or room scale)," wrote 239 scientists in the Oxford Academic journal Clinical Infectious Diseases.
They recommended new measures including installing high-grade air filters and preventing overcrowding in buildings and transport systems.
"Hand washing and social distancing are appropriate, but in our view, insufficient to provide protection from virus-carrying respiratory micro-droplets released into the air by infected people," they said.
The United States has struggled to respond to the devastation wrought by the virus, with its national death toll surpassing 130,000 out of 2.9 million confirmed cases, and many states hit by increasing infections after lockdowns were eased.
Hospital beds are full in parts of Texas, while calls for fresh stay-at-home orders are growing.
Some mayors have said their cities reopened too early, as President Donald Trump tried to downplay the severity of the crisis, instead prioritising economic reopening.
The annual July 4 holiday weekend – during which Trump eschewed wearing a mask and falsely asserted that "99%" of cases are not serious – was overshadowed by growing evidence that the fractured pandemic response has exacted a heavy price across the US south and west.
"Our hospitals here in Harris County, Houston, and 33 other cities... they're into surge capacities. So their operational beds are taken up," said Lina Hidalgo, chief executive of Texas's Harris County, which includes Houston.
"Restaurants are still open. Indoor events can take place no matter the size," she told ABC. "What we need right now is to do what works, which is a stay-home order."
The US is now recording tens of thousands of new cases a day, with a peak of 57,000 on Friday alone.
In South Africa, dozens of military medics were deployed on Sunday after a surge in infections in East Cape province.
Like India, South Africa imposed some of the strictest stay-at-home measures in late March in a bid to limit Covid-19's spread, but infection numbers are rising daily as lockdown rules are gradually eased.
Iran on Monday announced 160 new deaths, just three shy of the country's highest official one-day toll, registered the day before.