Britain's Prime Minister Boris Johnson looks at a water sample in a classroom during a visit to Severn Trent Academy in Coventry, West Midlands, Britain, May 7, 2021. REUTERS/Phil Noble/Pool

A woman reacts as a healthcare worker takes a nasal swab sample for a coronavirus disease (COVID-19) test at a government-run hospital, amidst the spread of the disease in Kolkata, India, May 6, 2021. REUTERS/Rupak De Chowdhuri TPX IMAGES OF THE DAY

A woman blows into a plastic bag as she takes her breath sample to be tested for the coronavirus disease (COVID-19) using the GeNose C19 (GeNose) COVID-19 detection tool, during "mudik" rush when people return to their hometowns ahead of the Eid al-Fitr celebration, at the train station in Jakarta, Indonesia, May 5, 2021. Picture taken through glass. REUTERS/Ajeng Dinar Ulfiana

A health worker takes a nasal swab sample from a man from Klong Toey community, for a coronavirus disease (COVID-19) test, in Bangkok, Thailand, May 4, 2021. REUTERS/Soe Zeya Tun

Former senator Bill Nelson points to the Lunar sample from Apollo 16 collected by astronaut John Young, accompanied by his wife Grace, his son Bill Jr., and his daughter Nan Ellen, after being sworn in by Vice President Kamala Harris as NASA's 14th administrator, with guests Pam Melroy, nominee for Deputy NASA Administrator, and Charlie Bolden, former NASA Administrator, holding a laptop with former administrator Jim Bridenstine on the screen, in the Eisenhower Executive Office Building at the White House in Washington, U.S., May 3, 2021. REUTERS/Cheriss May

A healthcare worker takes a nasal swab sample from a person for a coronavirus disease (COVID-19) test, at a temple near Klong Toey slum community in Bangkok, Thailand, May 3, 2021. REUTERS/Juarawee Kittisilpa

Pharmacist Maite Baleri collects a swab sample from Isabel Mier, 21, during a rapid antigen test before dancing inside La Merce cultural center during Open Girona initiative, which aims to provide a pilot digital health pass scheme to reopen restaurants and businesses amid the coronavirus disease (COVID-19) pandemic, in Girona, Spain May 1, 2021. Picture taken May 1, 2021. REUTERS/Nacho Doce

Pharmacist Maite Baleri collects a swab sample from Oriol Garreta, 22, during a rapid antigen test before dancing inside La Merce cultural center during Open Girona initiative, which aims to provide a pilot digital health pass scheme to reopen restaurants and businesses amid the coronavirus disease (COVID-19) pandemic, in Girona, Spain May 1, 2021. Picture taken May 1, 2021. REUTERS/Nacho Doce

A healthcare worker shows a swab sample taken to test the coronavirus disease (COVID-19) at a COVID-19 testing centre at Brussels' International airport premises, in Zaventem, Belgium April 28, 2021. REUTERS/Yves Herman

A healthcare worker shows a swab sample taken to test the coronavirus disease (COVID-19) at a COVID-19 testing centre at Brussels' International airport premises, in Zaventem, Belgium April 28, 2021. REUTERS/Yves Herman

A healthcare worker takes a swab sample from a woman to test for the coronavirus disease (COVID-19) at a COVID-19 testing centre at Brussels' International airport premises, in Zaventem, Belgium April 28, 2021. REUTERS/Yves Herman

A healthcare worker takes a swab sample from a man to test for the coronavirus disease (COVID-19) at a COVID-19 testing centre at Brussels' International airport premises, in Zaventem, Belgium April 28, 2021. REUTERS/Yves Herman

A healthcare worker takes a swab sample from a man to test for the coronavirus disease (COVID-19) at a COVID-19 testing centre at Brussels' International airport premises, in Zaventem, Belgium April 28, 2021. REUTERS/Yves Herman

Tokyo 2020 Games Delivery Officer Hidemasa Nakamura holds a sample of the Version Two of Tokyo 2020 Playbook during a media conference in Tokyo, Japan April 28, 2021. Franck Robichon/Pool via REUTERS

A coronavirus disease (COVID-19) antigen test sample is placed in the care of a tester in central Copenhagen, Denmark, April 23, 2021. Picture taken on April 23, 2021. REUTERS/Tim Barsoe

A schoolboy gives a sample during a COVID-19 saliva test at Lepeltier primary school in La Trinite, near Nice, amid the coronavirus disease (COVID-19) outbreak in France, April 26, 2021. REUTERS/Eric Gaillard

A schoolgirl gives a sample during a COVID-19 saliva test at Lepeltier primary school in La Trinite, near Nice, amid the coronavirus disease (COVID-19) outbreak in France, April 26, 2021. REUTERS/Eric Gaillard

A schoolboy gives a sample during a COVID-19 saliva test at Lepeltier primary school in La Trinite, near Nice, amid the coronavirus disease (COVID-19) outbreak in France, April 26, 2021. REUTERS/Eric Gaillard

A schoolgirl gives a sample during a COVID-19 saliva test at Lepeltier primary school in La Trinite, near Nice, amid the coronavirus disease (COVID-19) outbreak in France, April 26, 2021. REUTERS/Eric Gaillard

An employee of Vulcan Energy Resources works on a sample of geothermal water in Eggenstein near Karlsruhe, Germany, April 23, 2021. Picture taken April 23, 2021. REUTERS/Ralph Orlowski

An employee of Vulcan Energy Resources works on a sample of geothermal water in Eggenstein near Karlsruhe, Germany, April 23, 2021. Picture taken April 23, 2021. REUTERS/Ralph Orlowski

An employee of Vulcan Energy Resources works on a sample of geothermal water in Eggenstein near Karlsruhe, Germany, April 23, 2021. Picture taken April 23, 2021. REUTERS/Ralph Orlowski

An employee of Vulcan Energy Resources works on a laboratory sample of lithium chloride in Eggenstein near Karlsruhe, Germany, April 23, 2021. Picture taken April 23, 2021. REUTERS/Ralph Orlowski

Katharina Gerber, product manager of Vulcan Energy Resources, works on a sample of geothermal water in Eggenstein near Karlsruhe, Germany, April 23, 2021. Picture taken April 23, 2021. REUTERS/Ralph Orlowski

Katharina Gerber, product manager of Vulcan Energy Resources, works on a sample of geothermal water in Eggenstein near Karlsruhe, Germany, April 23, 2021. Picture taken April 23, 2021. REUTERS/Ralph Orlowski

Cho Mi-heui, vice president of PoongLim Pharmatech Inc. showcases a sample of a low dead space (LDS) syringe after an interview with Reuters at a company office in Gunsan, South Korea, April 5, 2021. Picture taken April 5, 2021. REUTERS/Heo Ran

Citizen scientist Sarah Cook (R) examines a floating sample for microplastics in Kiama, Australia, March 30, 2021. Picture taken March 30, 2021. REUTERS/James Redmayne

Citizen scientist Sarah Cook examines a sample for microplastics in Kiama, Australia, March 30, 2021. Picture taken March 30, 2021. REUTERS/James Redmayne

Citizen scientists use tweezers to remove microplastics from a sample to a separate container at Manly Cove Beach in Sydney, Australia, April 17, 2021. Picture taken April 17, 2021. REUTERS/James Redmayne

Pula operations manager Daniel Mbuvi and field officer Ruth Wambua take measurements for the area that will be used as a sample for insurance payout, at Waki Munyalo's farm in Kitui county, Kenya, March 17, 2021. Picture taken March 17, 2021. REUTERS/Monicah Mwangi

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

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 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

Geologist Zach Zenns examines copper ore samples from the exploratory mine shaft 10 in the geological facility of Resolution Copper in Superior, Arizona, U.S., March 30, 2021. Picture taken March 30, 2021. REUTERS/Caitlin O'Hara

Copper ore samples from the exploratory mine shaft 10 are packaged in the geological facility of Resolution Copper in Superior, Arizona, U.S., March 30, 2021. Picture taken March 30, 2021. REUTERS/Caitlin O'Hara

Copper ore samples from the exploratory mine shaft 10 are seen in the geological facility of Resolution Copper in Superior, Arizona, U.S., March 30, 2021. Picture taken March 30, 2021. REUTERS/Caitlin O'Hara

A healthcare worker in personal protective equipment (PPE) collects a swab sample from a woman, amidst the spread of the coronavirus disease (COVID-19), at a railway station in Mumbai, India, April 16, 2021. REUTERS/Francis Mascarenhas

Director of Smart Climate Innovation Academy Simon Tugumisiriza samples fibre extracted from the sheaths of banana trunks as he airs them in the sun before they are woven into different products, at the TexFad plant in Sonde settlement of Mukono near Kampala, Uganda, April 3, 2021. Picture taken April 3, 2021. REUTERS/Abubaker Lubowa

Director of Smart Climate Innovation Academy Simon Tugumisiriza samples fibre extracted from the sheaths of banana trunks at the TexFad plant in Sonde settlement of Mukono near Kampala, Uganda, April 3, 2021. Picture taken April 3, 2021. REUTERS/Abubaker Lubowa

Healthcare workers take nasal swab samples from people, as they need to be tested to pass the barricade for the non-stop "Covid-free" direct train from Rome to Milan, as the outbreak of the coronavirus disease (COVID-19) continues, in Rome, Italy, April 16, 2021. REUTERS/Yara Nardi

A healthcare worker takes a nasal swab sample from a man, as he needs to be tested to pass the barricade for the non-stop "Covid-free" direct train from Rome to Milan, as the outbreak of the coronavirus disease (COVID-19) continues, in Rome, Italy, April 16, 2021. REUTERS/Yara Nardi

A healthcare worker takes a nasal swab sample from a person for a coronavirus disease (COVID-19) test, as the country deals with a fresh wave of infections after tackling earlier outbreaks, in Bangkok, Thailand April 16, 2021. REUTERS/Athit Perawongmetha

A healthcare worker takes a nasal swab sample from a person for a coronavirus disease (COVID-19) test, as the country deals with a fresh wave of infections after tackling earlier outbreaks, in Bangkok, Thailand April 16, 2021. REUTERS/Athit Perawongmetha

A healthcare worker takes a nasal swab sample from a police officer for a coronavirus disease (COVID-19) test, as the country deals with a fresh wave of infections after tackling earlier outbreaks, in Bangkok, Thailand April 16, 2021. REUTERS/Athit Perawongmetha

A healthcare worker takes a nasal swab sample from a child for a coronavirus disease (COVID-19) test, as the country deals with a fresh wave of infections after tackling earlier outbreaks, in Bangkok, Thailand April 16, 2021. REUTERS/Athit Perawongmetha

A healthcare worker takes a nasal swab sample from a person for a coronavirus disease (COVID-19) test, as the country deals with a fresh wave of infections after tackling earlier outbreaks, in Bangkok, Thailand April 16, 2021. REUTERS/Athit Perawongmetha

A healthcare worker takes a nasal swab sample from a person for a coronavirus disease (COVID-19) test, as the country deals with a fresh wave of infections after tackling earlier outbreaks, in Bangkok, Thailand April 16, 2021. REUTERS/Athit Perawongmetha

A healthcare worker takes a nasal swab sample from a person for a coronavirus disease (COVID-19) test, as the country deals with a fresh wave of infections after tackling earlier outbreaks, in Bangkok, Thailand April 16, 2021. REUTERS/Athit Perawongmetha

A healthcare worker takes a nasal swab sample from a person for a coronavirus disease (COVID-19) test, as the country deals with a fresh wave of infections after tackling earlier outbreaks, in Bangkok, Thailand April 16, 2021. REUTERS/Athit Perawongmetha

A healthcare worker takes a nasal swab sample from a person for a coronavirus disease (COVID-19) test, as the country deals with a fresh wave of infections after tackling earlier outbreaks, in Bangkok, Thailand April 16, 2021. REUTERS/Athit Perawongmetha TPX IMAGES OF THE DAY

A healthcare worker takes a nasal swab sample from a person for a coronavirus disease (COVID-19) test, as the country deals with a fresh wave of infections after tackling earlier outbreaks, in Bangkok, Thailand April 16, 2021. REUTERS/Athit Perawongmetha

A healthcare worker takes a nasal swab sample from a person for a coronavirus disease (COVID-19) test, as the country deals with a fresh wave of infections after tackling earlier outbreaks, in Bangkok, Thailand April 16, 2021. REUTERS/Athit Perawongmetha

A healthcare worker takes a nasal swab sample from a person for a coronavirus disease (COVID-19) test, as the country deals with a fresh wave of infections after tackling earlier outbreaks, in Bangkok, Thailand April 16, 2021. REUTERS/Athit Perawongmetha

Doctor Silvana Zammit takes a swab sample from Rebecca Zammit Lupi, a 14-year-old cancer patient, after Rebecca displayed some symptoms of the coronavirus disease (COVID-19), in her room at Rainbow Ward in Sir Anthony Mamo Oncology Centre at Mater Dei Hospital, during the COVID-19 outbreak, in Tal-Qroqq, Malta, May 5, 2020. The test result was negative. REUTERS/Darrin Zammit Lupi SEARCH "REBECCA LUPI" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES THE IMAGES SHOULD ONLY BE USED TOGETHER WITH THE STORY - NO STAND-ALONE USES

An Allianz employee takes a nasal swab sample for a coronavirus disease (COVID-19) test before working at the Allianz Campus in Berlin, Germany, April 15, 2021. REUTERS/Michele Tantussi

A healthcare worker takes a swab sample from an Ultra-Orthodox Jewish man for the coronavirus disease (COVID-19) test, after returning from overseas, at Ben Gurion International Airport in Lod, near Tel Aviv, Israel April 13, 2021. REUTERS/Ronen Zvulun

Healthcare workers talk as they take a swab sample from an Ultra-Orthodox Jewish man for the coronavirus disease (COVID-19) test, as people return from overseas, at Ben Gurion International Airport in Lod, near Tel Aviv, Israel April 13, 2021. REUTERS/Ronen Zvulun

A healthcare worker collects swab samples for the coronavirus disease (COVID-19) test as people return from overseas, at Ben Gurion International Airport in Lod, near Tel Aviv, Israel April 13, 2021. REUTERS/Ronen Zvulun

A healthcare worker takes a swab sample from an Ultra-Orthodox Jewish man for the coronavirus disease (COVID-19) test, after returning from overseas, at Ben Gurion International Airport in Lod, near Tel Aviv, Israel April 13, 2021. REUTERS/Ronen Zvulun

A healthcare worker takes a swab sample from an Ultra-Orthodox Jewish man for the coronavirus disease (COVID-19) test, after returning from overseas, at Ben Gurion International Airport in Lod, near Tel Aviv, Israel April 13, 2021. REUTERS/Ronen Zvulun