Coronavirus deaths surged past 100,000 in Europe as the world's top musicians joined forces for a virtual concert, hoping to spread cheer to billions stuck at home under lockdown. A-listers including the Rolling Stones, Taylor Swift, Stevie Wonder and teen superstar Billie Eilish entertained fans with a six-hour online extravaganza celebrating healthcare workers. The event, set up by advocacy group Global Citizen with the World Health Organization, aimed to cultivate a sense of community during the pandemic, which has ravaged the global economy with nearly 2.3 million confirmed infections in total. At least 157,000 people have been killed by Covid-19 with two-thirds of the deaths in Europe, according to an AFP tally, and nearly a quarter of fatalities in the United States, the worst-hit country. The highly contagious disease first emerged late last year in the city of Wuhan in central China. It was likely transmitted to humans at a market where exotic animals were slaughtered, Chinese scientists have said. Conspiracy theories that the virus came from a maximum-security laboratory have been brought into the mainstream in recent days by US government officials. Secretary of State Mike Pompeo said an investigation was underway into how the virus "got out into the world". But the director of the virology institute in Wuhan rejected the claims on Saturday, saying it was "impossible" that the disease could have come from his lab. The US has the highest caseload of any country, with more than 735,000 confirmed infections, and by Sunday had lost 38,910 people to the virus, according to a tally from Johns Hopkins University. Progress was marked in some places, with New York state reporting the lowest number of deaths in weeks, which Governor Andrew Cuomo attributed largely to social distancing. But as Americans and others around the world chafe after weeks under stay-at-home orders, resentment is rising. Anti-lockdown protests on Saturday drew hundreds of people at the capitols of states including Texas, Maryland, New Hampshire and Ohio. Many demonstrators waved American flags and some carried arms. The small but spreading movement demanding a quick end to state-ordered confinement drew encouragement from Trump, who tweeted that three states should be "liberated" from the stay-home orders. The president has called for a rapid return to normality to limit damage to the US economy - while largely leaving the final decision on easing lockdowns to state officials. At a White House briefing, Trump also warned that China could face consequences if it was "knowingly responsible" for the coronavirus outbreak. "It could have been stopped in China before it started and it wasn't," Trump said. "And now the whole world is suffering." "If it was a mistake, a mistake is a mistake," he said. "But if they were knowingly responsible, yeah, then there should be consequences." Mounting evidence suggests that social distancing slowed the pandemic after more than half of humanity - 4.5 billion people - were confined to their homes. Stay-at-home orders have been enforced in Italy and Spain, both still the hardest-hit countries in Europe, with death tolls over 20,000, followed by France, which has recorded more than 19,000 fatalities. As governments around the world grapple with when and how to ease lockdowns, Spain on Saturday extended its nationwide shutdown to May 9. Japan, Britain and Mexico have all expanded their movement restrictions. Yet elsewhere, signs that the outbreak could be easing prompted Switzerland, Denmark and Finland to begin reopening shops and schools this week. Germany has declared the virus "under control" after 3,400 deaths, and is beginning the delicate task of lifting some restrictions without triggering a secondary outbreak - with some shops allowed to reopen Monday, and some children returning to school within weeks. Iran also allowed some Tehran businesses to reopen Saturday despite the Middle East's deadliest outbreak. "How can I keep staying home? My family is hungry," said Hamdollah Mahmoudi, 45, a shopworker in Tehran's Grand Bazaar. Meanwhile, many of the world's 260 million Orthodox Christians are preparing to mark Easter without attending church services. In Zimbabwe, mass rallies and military parades to mark the country's 40th anniversary of independence from British colonial rule were cancelled. And Buckingham Palace announced that Queen Elizabeth II will not mark her birthday on Tuesday with a traditional gun salute. Australia has called for an independent investigation into the global response to the pandemic, including the Worl Health Organization's handling of the crisis. Its foreign minister said the country would "insist" on a review that would probe, in part, China's response to the outbreak.