Members of a helicopter tranport crew watch a 2.600kg ferroconcret block rolling down during rockfall experiments of the WSL Institute for Snow and Avalanche Research (SLF) in Schiers, Switzerland April 15, 2021. Picture taken April 15, 2021. REUTERS/Arnd Wiegmann

Members of a helicopter tranport crew bring a 2.600kg ferroconcret block in position during rockfall experiments of the WSL Institute for Snow and Avalanche Research (SLF) in Schiers, Switzerland April 15, 2021. Picture taken April 15, 2021. REUTERS/Arnd Wiegmann

A member of a helicopter tranport crew stands behind as ferroconcret block is lifted up during rockfall experiments of the WSL Institute for Snow and Avalanche Research (SLF) in Schiers, Switzerland April 15, 2021. Picture taken April 15, 2021. REUTERS/Arnd Wiegmann

Andrin Caviezel, researcher at the WSL Institute for Snow and Avalanche Research (SLF) checks a 3.200kg ferroconcret block before rockfall experiments in Schiers, Switzerland April 15, 2021. Picture taken April 15, 2021. REUTERS/Arnd Wiegmann

A member of a helicopter tranport crew watches a 2.600kg ferroconcret block rolling down during rockfall experiments of the WSL Institute for Snow and Avalanche Research (SLF) in Schiers, Switzerland April 15, 2021. Picture taken April 15, 2021. REUTERS/Arnd Wiegmann

A 2.600kg ferroconcret block is seen during rockfall experiments of the WSL Institute for Snow and Avalanche Research (SLF) in Schiers, Switzerland April 15, 2021. Picture taken April 15, 2021. REUTERS/Arnd Wiegmann

Members of a helicopter tranport crew watch a 2.600kg ferroconcret block rolling down during rockfall experiments of the WSL Institute for Snow and Avalanche Research (SLF) in Schiers, Switzerland April 15, 2021. Picture taken April 15, 2021. REUTERS/Arnd Wiegmann

A 2.600kg ferroconcret block is seen during rockfall experiments of the WSL Institute for Snow and Avalanche Research (SLF) in Schiers, Switzerland April 15, 2021. Picture taken April 15, 2021. REUTERS/Arnd Wiegmann

An Eurocopter As 332 L Super Puma helicopter is seen during transports ferroconcret blocks before rockfall experiments of the WSL Institute for Snow and Avalanche Research (SLF) in Schiers, Switzerland April 15, 2021. Picture taken April 15, 2021. REUTERS/Arnd Wiegmann

A 2.600kg ferroconcret block is seen during rockfall experiments of the WSL Institute for Snow and Avalanche Research (SLF) in Schiers, Switzerland April 15, 2021. Picture taken April 15, 2021. REUTERS/Arnd Wiegmann

A 2.600kg ferroconcret block is seen during rockfall experiments of the WSL Institute for Snow and Avalanche Research (SLF) in Schiers, Switzerland April 15, 2021. Picture taken April 15, 2021. REUTERS/Arnd Wiegmann

An Eurocopter As 332 L Super Puma helicopter transports a ferroconcret block before rockfall experiments of the WSL Institute for Snow and Avalanche Research (SLF) in Schiers, Switzerland April 15, 2021. Picture taken April 15, 2021. REUTERS/Arnd Wiegmann

Andrin Caviezel (L), researcher at the WSL Institute for Snow and Avalanche Research (SLF) places a measuring sensor into a 3.200kg ferroconcret block before rockfall experiments in Schiers, Switzerland April 15, 2021. Picture taken April 15, 2021. REUTERS/Arnd Wiegmann

A health worker wears personal protective equipment (PPE) prior to conducting swab tests in a household where coronavirus disease (COVID-19) positive cases have been recorded, in Quezon City, Metro Manila, Philippines, April 20, 2021. REUTERS/Lisa Marie David

A makeshift barrier and a sign indicating that the street is under lockdown are seen, amid rising coronavirus disease (COVID-19) cases, in Quezon City, Metro Manila, Philippines, April 20, 2021. REUTERS/Lisa Marie David

A health worker collects a swab sample for a coronavirus disease (COVID-19) test from a woman with a COVID-19 positive household member, as part of the government's contact tracing program, in Quezon City, Metro Manila, Philippines, April 20, 2021. REUTERS/Lisa Marie David

Health workers prepare to conduct coronavirus disease (COVID-19) tests in a household where positive cases have been recorded, as part of the government's contact tracing program, in Quezon City, Metro Manila, Philippines, April 20, 2021. REUTERS/Lisa Marie David

A woman mourns with her son after her husband died due to the coronavirus disease (COVID-19) outside a mortuary of a COVID-19 hospital in Ahmedabad, India, April 20, 2021. REUTERS/Amit Dave

A health worker collects a swab sample for a coronavirus disease (COVID-19) test from a man with a COVID-19 positive household member, as part of the government's contact tracing program, in Quezon City, Metro Manila, Philippines, April 20, 2021. REUTERS/Lisa Marie David

A worker stands as a tanker is filled with liquid oxygen to be transported to a COVID-19 hospital, amidst the spread of the coronavirus disease (COVID-19) in Ahmedabad, India, April 20, 2021. REUTERS/Amit Dave

Ng Yu Zhi, a director of Envy Global Trading, arrives at the State Court in Singapore April 20, 2021. REUTERS/Edgar Su

A patient with breathing problem is seen inside an ambulance waiting to enter a COVID-19 hospital for treatment, amidst the spread of the coronavirus disease (COVID-19) in Ahmedabad, India, April 20, 2021. REUTERS/Amit Dave

A woman is consoled after her husband died due to the coronavirus disease (COVID-19) outside a mortuary of a COVID-19 hospital in Ahmedabad, India, April 20, 2021. REUTERS/Amit Dave

A health worker collects a swab sample for a coronavirus disease (COVID-19) test from a man with a COVID-19 positive household member, as part of the government's contact tracing program, in Quezon City, Metro Manila, Philippines, April 20, 2021. REUTERS/Lisa Marie David

Ng Yu Zhi (R), a director of Envy Global Trading, arrives at the State Court in Singapore April 20, 2021. REUTERS/Edgar Su

Health workers prepare to conduct coronavirus disease (COVID-19) tests in a household where positive cases have been recorded, as part of the government's contact tracing program, in Quezon City, Metro Manila, Philippines, April 20, 2021. REUTERS/Lisa Marie David

Ng Yu Zhi, a director of Envy Global Trading, arrives at the State Court in Singapore April 20, 2021. REUTERS/Edgar Su

India leads the world in the daily average number of new infections reported, accounting for one in every four infections worldwide each day.

A view of the Christian Democratic Union party (CDU) headquarters in Berlin, Germany, April 20, 2021. REUTERS/Michele Tantussi

A view of the Christian Democratic Union party (CDU) headquarters in Berlin, Germany, April 20, 2021. REUTERS/Michele Tantussi

A view of the Christian Democratic Union party (CDU) headquarters in Berlin, Germany, April 20, 2021. REUTERS/Michele Tantussi

People stand near the Nissan logo during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

Members of the media stand in front of the Christian Democratic Union party (CDU) headquarters in Berlin, Germany, April 20, 2021. REUTERS/Michele Tantussi

People sit near an electric vehicle (EV) charging point of SAIC Motor's R brand displayed during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

A Chevrolet Corvette-1953 vehicle is seen displayed among other vehicles during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

People visit the Jeep booth during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

Visitors check a Geely Xingyue ePro vehicle displayed at the Geely booth during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

Visitors check an electric vehicle (EV) displayed at the Tesla booth during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

A GAC Trumpchi Empow vehicle is seen displayed during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

Staff members stand behind a counter bearing the Toyota logo and emblems of the Beijing 2022 Winter Olympics, during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

A Honda SUV e:Prototype electric vehicle (EV) is seen displayed during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

A staff member stands near a Baojun Kiwi electric vehicle (EV) equipped with DJI's intelligent driving system displayed during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

A display of Baojun Kiwi electric vehicle (EV) is seen at the booth of General Motors' China brand Baojun during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

People stand near an Aeolus Yixuan Max vehicle displayed at the Dongfeng Motor booth during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

Visitors stand near a Wuling Hong Guang MINI EV Macaron car displayed at its booth during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

The rising sun illuminates a fishing boat on the Yalu river, which separates North Korea's Sinuiju from China, in Dandong, Liaoning province, China April 20, 2021. REUTERS/Tingshu Wang

A worker stands between solar cell panels over the water surface of Sirindhorn Dam in Ubon Ratchathani, Thailand April 8, 2021. Picture taken April 8, 2021 with a drone. REUTERS/Prapan Chankaew

Two coyotes fight on the Mexico border in Gadsden, Arizona, U.S. April 19, 2021. REUTERS/Jim Urquhart

A worker kneels by one of the solar cell panels over the water surface of Sirindhorn Dam in Ubon Ratchathani, Thailand April 8, 2021. Picture taken April 8, 2021 with a drone. REUTERS/Prapan Chankaew

Workers walk between solar cell panels over the water surface of Sirindhorn Dam in Ubon Ratchathani, Thailand April 8, 2021. Picture taken April 8, 2021 with a drone. REUTERS/Prapan Chankaew

Workers walk between solar cell panels over the water surface of Sirindhorn Dam in Ubon Ratchathani, Thailand April 8, 2021. Picture taken April 8, 2021 with a drone. REUTERS/Prapan Chankaew

Workers walk between solar cell panels over the water surface of Sirindhorn Dam in Ubon Ratchathani, Thailand April 8, 2021. Picture taken April 8, 2021 with a drone. REUTERS/Prapan Chankaew

Workers walk between solar cell panels over the water surface of Sirindhorn Dam in Ubon Ratchathani, Thailand April 8, 2021. Picture taken April 8, 2021 with a drone. REUTERS/Prapan Chankaew

A staff member stands at the Jaguar Land Rover booth during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

A Pure Electric sign is seen above a Volvo vehicle displayed during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

A staff member stands in front of Volvo XC60 and XC90 SUVs displayed at its booth during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

A staff member cleans a Volvo S90 sedan displayed during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

Angela Rose Myers, president of the Minneapolis branch of the National Association for the Advancement of Colored People (NAACP), addresses demonstrators during a march through downtown after the closing statements in the trial of former police officer Derek Chauvin, who is facing murder charges in the death of George Floyd, in Minneapolis, Minnesota, U.S., April 19, 2021. REUTERS/Nicholas Pfosi

A Tesla logo is seen on the body of its electric vehicle (EV) during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song

Staff members stand near a Polestar 2 electric vehicle (EV) displayed during a media day for the Auto Shanghai show in Shanghai, China April 20, 2021. REUTERS/Aly Song