FILE - In this file photo dated Thursday June 24, 2021, European Council President Charles Michel, left, greets Luxembourg's Prime Minister Xavier Bettel during an EU summit at the European Council building in Brussels. The government of Luxembourg said Monday June 28, 2021, that Prime Minister Xavier Bettel has tested positive for COVID-19 and is in isolation for 10 days. (AP Photo/Olivier Matthys, FILE)

A medical worker collects a nasal swab sample during a mass screening for coronavirus at North Sumatra University Hospital in Medan, North Sumatra, Indonesia, Monday, June 28, 2021. The world's fourth most populous country has seen COVID-19 infections surge in recent weeks, putting pressure on hospitals and has added urgency to the government's plan to inoculate 1 million people each day by next month. (AP Photo/Binsar Bakkara)

People wear face masks to help protect against the spread of the coronavirus and go shopping at a traditional market after the COVID-19 alert rose to level 3 in Taipei, Taiwan, Monday, June 28, 2021. (AP Photo/Chiang Ying-ying)

Staff prepare to take COVID-19 tests at a testing station in Nelson Bay, Australia, Monday, June 28, 2021. Australia was battling to contain several COVID-19 clusters around the country on Monday in what some experts have described as the nation’s most dangerous stage of the pandemic since the earliest days. (AP Photo/Mark Baker)

People receive a dose of the COVID-19 vaccine at a mass vaccination clinic at Scotiabank Arena in Toronto on Sunday, June 27, 2021. (Cole Burston/The Canadian Press via AP)

People wear face masks to help protect against the spread of the coronavirus and go shopping at a traditional market after the COVID-19 alert rose to level 3 in Taipei, Taiwan, Monday, June 28, 2021. (AP Photo/Chiang Ying-ying)

A man rides a bicycle past a closed dance floor belted with police tape due to coronavirus in a park in Moscow, Russia, Sunday, June 27, 2021. Russia on Saturday, June 26, 2021 reported its highest daily COVID-19 death toll of the year as the country grapples with a sharp spike in infections that has brought new restrictions in some regions. (AP Photo/Alexander Zemlianichenko)

People walk along Regent Street in central London during a peaceful #FreedomToDance march organised by Save Our Scene, calling for easing of restrictions for music events, in London, Sunday June 27, 2021. Large crowds gathered in central London to protest over what they called the government's perceived disregard for the live music industry throughout the coronavirus pandemic. (Aaron Chown/PA via AP)

A bed it rolled out from an emergency tent erected to accommodate a surge of COVID-19 patients at a hospital in Bekasi, West Java, Indonesia, Monday, June 28, 2021. (AP Photo/Achmad Ibrahim)

Medical workers carry a woman on stretcher from an emergency tent erected to accommodate a surge of COVID-19 patients at a hospital in Bekasi, West Java, Indonesia, Monday, June 28, 2021.(AP Photo/Achmad Ibrahim)

A Sri Lankan health worker administers the second dose of Covishield, Serum Institute of India's version of the AstraZeneca vaccine to an elderly woman during a public vaccination drive against the coronavirus in Colombo, Sri Lanka, Monday, June 28, 2021. (AP Photo/Eranga Jayawardena)

A couple prepare to receive a COVID-19 test at a testing station in Nelson Bay, Australia, Monday, June 28, 2021. Australia was battling to contain several COVID-19 clusters around the country on Monday in what some experts have described as the nation’s most dangerous stage of the pandemic since the earliest days. (AP Photo/Mark Baker)

A woman sits inside an emergency tent accommodating a surge of COVID-19 patients at a hospital in Bekasi, West Java, Indonesia, Monday, June 28, 2021. (AP Photo/Achmad Ibrahim)

People gather near to parliament in central London during a #FreedomToDance march organised by Save Our Scene, calling for easing of restrictions for music events, in London, Sunday June 27, 2021. Large crowds gathered in central London to protest over what they called the government's perceived disregard for the live music industry throughout the coronavirus pandemic. (Aaron Chown/PA via AP)

People walk along Regent Street in central London during a #FreedomToDance march organised by Save Our Scene, calling for easing of restrictions for music events, in London, Sunday June 27, 2021. Large crowds gathered in central London to protest over what they called the government's perceived disregard for the live music industry throughout the coronavirus pandemic. (Aaron Chown/PA via AP)

People line up to register themselves and to get inoculated against COVID-19 at an urban health centre in Ahmedabad, India, Monday, June 28, 2021. (AP Photo/Ajit Solanki)

Police precede protesters, leading them along Regent Street in central London during a #FreedomToDance march organised by Save Our Scene, calling for easing of restrictions for music events, in London, Sunday June 27, 2021. Large crowds gathered in central London to protest over what they called the government's perceived disregard for the live music industry throughout the coronavirus pandemic. (Aaron Chown/PA via AP)

People walk along Regent Street in central London during a #FreedomToDance march organised by Save Our Scene, calling for easing of restrictions for music events, in London, Sunday June 27, 2021. Large crowds gathered in central London to protest over what they called the government's perceived disregard for the live music industry throughout the coronavirus pandemic. (Aaron Chown/PA via AP)