An advertisement truck, operated by Tokyo Metropolitan Government office, displaying messages that warns against the spread of the N501Y mutant COVID-19 strain, drives on the street in Tokyo, Japan May 14, 2021. REUTERS/Naoki Ogura

Keiko Yamamura, 58, a yoga instructor, poses for a portrait at Hie Shrine, after attending a tea ceremony in Tokyo, Japan, May 12, 2021. Yamamura is conflicted about the Games taking place. "Variant strains could enter, creating a terrible situation," she said. "But when I think of the athletes who have worked so hard, I'd like to let them do it." REUTERS/Kim Kyung-Hoon SEARCH "KYUNG-HOON PORTRAITS" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES

Vendors strain raisin juice at a shop during the holy month of Ramadan in Mosul, Iraq, April 17, 2021. Picture taken April 17, 2021. REUTERS/Khalid Al-Mousily

Vendors strain raisin juice at a shop during the holy month of Ramadan in Mosul, Iraq, April 17, 2021. Picture taken April 17, 2021. REUTERS/Khalid Al-Mousily

Vendors strain raisin juice at a shop during the holy month of Ramadan in Mosul, Iraq, April 17, 2021. Picture taken April 17, 2021. REUTERS/Khalid Al-Mousily

A vendor strains raisin juice at a shop during the holy month of Ramadan in Mosul, Iraq, April 17, 2021. Picture taken April 17, 2021. REUTERS/Khalid Al-Mousily

Dr Aaron Davis shows a previously lost species of coffee, Coffea stenophylla, that could be the climate change resilient strain the coffee industry has been looking for according to the botanist, at the Royal Botanic Gardens Kew, in London, Britain, April 15, 2021. Picture taken April 15, 2021. REUTERS/Stuart McDill

Dr Aaron Davis examines an arabica coffee tree at the Royal Botanic Gardens Kew, in London, Britain, April 15, 2021. A previously lost species of coffee could be the climate change resilient strain the coffee industry has been looking for according to the botanist. Picture taken April 15, 2021. REUTERS/Stuart McDill

Dr Aaron Davis shows a previously lost species of coffee, Coffea stenophylla, that could be the climate change resilient strain the coffee industry has been looking for according to the botanist, at the Royal Botanic Gardens Kew, in London, Britain, April 15, 2021. Picture taken April 15, 2021. REUTERS/Stuart McDill

Demonstrators hold placards depicting Brazilian President Jair Bolsonaro, which reads "The Bolsonaro strain, world danger", outside Brazil's embassy in Buenos Aires, Argentina April 14, 2021. REUTERS/Agustin Marcarian

A demonstrator holds a placard depicting Brazilian President Jair Bolsonaro, that reads "The Bolsonaro strain, world danger", outside Brazil's embassy in Buenos Aires, Argentina April 14, 2021. REUTERS/Agustin Marcarian

Cannabis entrepreneur Fetti smokes a hybrid strain joint of his marijuana brand "PowerPuff" at a home in the Queens borough of New York, U.S. April 1, 2021. Picture taken April 1, 2021. REUTERS/Shannon Stapleton

Bags of Cannabis hybrid strains from the marijuana brand "PowerPuff" are seen at a home in the Queens borough of New York, U.S. April 1, 2021. Picture taken April 1, 2021. REUTERS/Shannon Stapleton

Cannabis entrepreneur Fetti lights a hybrid strain joint of his marijuana brand "PowerPuff" at a home in the Queens borough of New York, U.S. April 1, 2021. Picture taken April 1, 2021. REUTERS/Shannon Stapleton

Cannabis entrepreneur Solo smokes a hybrid strain joint of his marijuana brand "HellaPuff" at a home in the Queens borough of New York, U.S. April 6, 2021. Picture taken April 6, 2021. REUTERS/Shannon Stapleton

Cannabis entrepreneur Solo looks down after smoking a hybrid strain joint of his marijuana brand "HellaPuff" at a home in the Queens borough of New York, U.S. April 6, 2021. Picture taken April 6, 2021. REUTERS/Shannon Stapleton

Cannabis entrepreneur Solo smokes a hybrid strain joint of his marijuana brand "HellaPuff" at a home in the Queens borough of New York, U.S. April 6, 2021. Picture taken April 6, 2021. REUTERS/Shannon Stapleton

A man walks past a graffiti of two people kissing while wearing face masks and the writing "In the face of the new strain, face mask for sure" amid a spike in infections of the coronavirus disease (COVID-19) that has led the government to extend lockdown measures, in Caracas, Venezuela April 6, 2021. REUTERS/Leonardo Fernandez Viloria

Hybrid strains of cannabis are pictured in a jar at a home in New York, U.S. in this illustration picture taken April 1, 2021. REUTERS/Shannon Stapleton/Illustration

A man holds hybrid strains of cannabis at a home in New York, U.S. in this illustration picture taken April 1, 2021. REUTERS/Shannon Stapleton/Illustration

A man holds hybrid strains of cannabis at a home in New York, U.S. in this illustration picture taken April 1, 2021. REUTERS/Shannon Stapleton/Illustration

Hybrid strains of cannabis are pictured in a jar at a home in New York, U.S. in this illustration picture taken April 1, 2021. REUTERS/Shannon Stapleton/Illustration

Hybrid strains of cannabis are pictured in a jar at a home in New York, U.S. in this illustration picture taken April 1, 2021. REUTERS/Shannon Stapleton/Illustration

A man smokes a hybrid strain joint of cannabis at his home in New York, U.S. April 1, 2021. New York Governor Andrew Cuomo signed a bill on Wednesday to legalize adult use of marijuana, making it the 15th U.S. state to allow recreational use of the drug. REUTERS/Shannon Stapleton

A man smokes a hybrid strain joint of cannabis at his home in New York, U.S. April 1, 2021. New York Governor Andrew Cuomo signed a bill on Wednesday to legalize adult use of marijuana, making it the 15th U.S. state to allow recreational use of the drug. REUTERS/Shannon Stapleton TPX IMAGES OF THE DAY

A man lights a hybrid strain joint of cannabis at his home in New York, U.S. April 1, 2021. New York Governor Andrew Cuomo signed a bill on Wednesday to legalize adult use of marijuana, making it the 15th U.S. state to allow recreational use of the drug. REUTERS/Shannon Stapleton

A man smokes a hybrid strain joint of cannabis at his home in New York, U.S. April 1, 2021. New York Governor Andrew Cuomo signed a bill on Wednesday to legalize adult use of marijuana, making it the 15th U.S. state to allow recreational use of the drug. REUTERS/Shannon Stapleton

A hybrid strain of cannabis sits in a bag at a home in New York, U.S. April 1, 2021. New York Governor Andrew Cuomo signed a bill on Wednesday to legalize adult use of marijuana, making it the 15th U.S. state to allow recreational use of the drug. REUTERS/Shannon Stapleton

A man breaks up a piece of flower from a hybrid strain to roll a joint of cannabis to smoke at his home in New York, U.S. April 1, 2021. New York Governor Andrew Cuomo signed a bill on Wednesday to legalize adult use of marijuana, making it the 15th U.S. state to allow recreational use of the drug. REUTERS/Shannon Stapleton

A man breaks up a piece of flower from a hybrid strain to roll a joint of cannabis to smoke at his home in New York, U.S. April 1, 2021. New York Governor Andrew Cuomo signed a bill on Wednesday to legalize adult use of marijuana, making it the 15th U.S. state to allow recreational use of the drug. REUTERS/Shannon Stapleton

A man rolls a hybrid strain joint of cannabis to smoke at his home in New York, U.S. April 1, 2021. New York Governor Andrew Cuomo signed a bill on Wednesday to legalize adult use of marijuana, making it the 15th U.S. state to allow recreational use of the drug. REUTERS/Shannon Stapleton

A man smokes a hybrid strain joint of cannabis at his home in New York, U.S. April 1, 2021. New York Governor Andrew Cuomo signed a bill on Wednesday to legalize adult use of marijuana, making it the 15th U.S. state to allow recreational use of the drug. REUTERS/Shannon Stapleton

A man smokes a hybrid strain joint of cannabis at his home in New York, U.S. April 1, 2021. New York Governor Andrew Cuomo signed a bill on Wednesday to legalize adult use of marijuana, making it the 15th U.S. state to allow recreational use of the drug. REUTERS/Shannon Stapleton

A man smokes a hybrid strain joint of cannabis at his home in New York, U.S. April 1, 2021. New York Governor Andrew Cuomo signed a bill on Wednesday to legalize adult use of marijuana, making it the 15th U.S. state to allow recreational use of the drug. REUTERS/Shannon Stapleton

A man smokes a hybrid strain joint of cannabis at his home in New York, U.S. April 1, 2021. New York Governor Andrew Cuomo signed a bill on Wednesday to legalize adult use of marijuana, making it the 15th U.S. state to allow recreational use of the drug. REUTERS/Shannon Stapleton

Phillip Alviola, a bat ecologist, hikes towards a bat roost at Mount Makiling in Los Banos, Laguna province, Philippines, February 18, 2021. "What we're trying to look into are other strains of coronavirus that have the potential to jump to humans," said Alviola. "If we know the virus itself and we know where it came from, we know how to isolate that virus geographically." REUTERS/Eloisa Lopez SEARCH "LOPEZ BATS" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES

Phillip Alviola, a bat ecologist, holds a bat that was captured from Mount Makiling in Los Banos, Laguna province, Philippines, March 5, 2021. "What we're trying to look into are other strains of coronavirus that have the potential to jump to humans," said Alviola. "If we know the virus itself and we know where it came from, we know how to isolate that virus geographically." REUTERS/Eloisa Lopez SEARCH "LOPEZ BATS" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES TPX IMAGES OF DAY

Phillip Alviola, a bat ecologist, takes an oral swab from a bat that was captured at Mount Makiling in Los Banos, Laguna province, Philippines, March 5, 2021. "What we're trying to look into are other strains of coronavirus that have the potential to jump to humans," said Alviola. "If we know the virus itself and we know where it came from, we know how to isolate that virus geographically." REUTERS/Eloisa Lopez SEARCH "LOPEZ BATS" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES

Phillip Alviola, a bat ecologist, takes an oral swab from a bat that was captured from a building at the University of the Philippines Los Banos (UPLB), in Los Banos, Laguna province, Philippines, February 19, 2021. "What we're trying to look into are other strains of coronavirus that have the potential to jump to humans," said Alviola. "If we know the virus itself and we know where it came from, we know how to isolate that virus geographically." REUTERS/Eloisa Lopez SEARCH "LOPEZ BATS" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES TPX IMAGES OF DAY

Phillip Alviola, a bat ecologist, takes a rectal swab from a bat that was captured from a building at the University of the Philippines Los Banos (UPLB), in Los Banos, Laguna province, Philippines, February 19, 2021. "What we're trying to look into are other strains of coronavirus that have the potential to jump to humans," said Alviola. "If we know the virus itself and we know where it came from, we know how to isolate that virus geographically." REUTERS/Eloisa Lopez SEARCH "LOPEZ BATS" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES

Phillip Alviola, a bat ecologist, measures a bat that was captured from a building at the University of the Philippines Los Banos (UPLB) in Los Banos, Laguna province, Philippines, February 19, 2021. "What we're trying to look into are other strains of coronavirus that have the potential to jump to humans," said Alviola. "If we know the virus itself and we know where it came from, we know how to isolate that virus geographically." REUTERS/Eloisa Lopez SEARCH "LOPEZ BATS" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES

Phillip Alviola, a bat ecologist, checks the wing of a bat that was captured from a building at the University of the Philippines Los Banos (UPLB), in Los Banos, Laguna province, Philippines, February 19, 2021. "What we're trying to look into are other strains of coronavirus that have the potential to jump to humans," said Alviola. "If we know the virus itself and we know where it came from, we know how to isolate that virus geographically." REUTERS/Eloisa Lopez SEARCH "LOPEZ BATS" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES

Phillip Alviola, a bat ecologist, attempts to catch a bat that was caught on a mist net that was set up in front of a building with a bat roost at the University of the Philippines Los Banos (UPLB), in Los Banos, Laguna province, Philippines, February 19, 2021. "What we're trying to look into are other strains of coronavirus that have the potential to jump to humans," said Alviola. "If we know the virus itself and we know where it came from, we know how to isolate that virus geographically." REUTERS/Eloisa Lopez SEARCH "LOPEZ BATS" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES

Phillip Alviola, a bat ecologist, catches a bat that was caught in a mist net in front of a building with a bat roost at the University of the Philippines Los Banos (UPLB), in Los Banos, Laguna province, Philippines, February 19, 2021. "What we're trying to look into are other strains of coronavirus that have the potential to jump to humans," said Alviola. "If we know the virus itself and we know where it came from, we know how to isolate that virus geographically." REUTERS/Eloisa Lopez SEARCH "LOPEZ BATS" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES

Soldiers stand at an empty square in front of the Royal Palace, after local authorities closed the seaside walkway and piazzas due to fears over the coronavirus disease (COVID-19) infections and strain on the Campania region's hospitals, in Naples, Italy, March 11, 2021. REUTERS/Ciro de Luca

A military vehicle is seen at an empty square in front of the Royal Palace, after local authorities closed the seaside walkway and piazzas due to fears over the coronavirus disease (COVID-19) infections and strain on the Campania region's hospitals, in Naples, Italy, March 11, 2021. REUTERS/Ciro de Luca

The seaside walkway 'Lungomare' is closed along with piazzas, as fears rise over the coronavirus disease (COVID-19) infections and its strain on the Campania region's hospitals, in Naples, Italy, March 11, 2021. REUTERS/Ciro de Luca

A view of closed businesses near the seaside walkway 'Lungomare', which is closed along with piazzas, as fears rise over the coronavirus disease (COVID-19) infections and its strain on the Campania region's hospitals, in Naples, Italy, March 11, 2021. REUTERS/Ciro de Luca

The seaside walkway 'Lungomare' is closed along with piazzas, as fears rise over the coronavirus disease (COVID-19) infections and its strain on the Campania region's hospitals, in Naples, Italy, March 11, 2021. REUTERS/Ciro de Luca

A police car drives by the closed seaside walkway 'Lungomare', which is close due to fears over the coronavirus disease (COVID-19) infections and its strain on the Campania region's hospitals, in Naples, Italy, March 11, 2021. REUTERS/Ciro de Luca

The seaside walkway 'Lungomare' is closed along with piazzas, as fears rise over the coronavirus disease (COVID-19) infections and its strain on the Campania region's hospitals, in Naples, Italy, March 11, 2021. REUTERS/Ciro de Luca

A view of the closed Villa Comunale park near the seaside walkway 'Lungomare', as fears rise over the coronavirus disease (COVID-19) infections and its strain on the Campania region's hospitals, in Naples, Italy, March 11, 2021. REUTERS/Ciro de Luca

A view of the closed Villa Comunale park near the seaside walkway 'Lungomare', as fears rise over the coronavirus disease (COVID-19) infections and its strain on the Campania region's hospitals, in Naples, Italy, March 11, 2021. REUTERS/Ciro de Luca

A view of closed businesses and parked cars near the seaside walkway 'Lungomare', which is closed along with piazzas, as fears rise over the coronavirus disease (COVID-19) infections and its strain on the Campania region's hospitals, in Naples, Italy, March 11, 2021. REUTERS/Ciro de Luca

A view of a closed children's park as fears rise over the coronavirus disease (COVID-19) infections and strain on the Campania region's hospitals, in Naples, Italy, March 11, 2021. REUTERS/Ciro de Luca

An empty town square is seen after the local authorities closed the seaside walkway and piazzas due to fears over the coronavirus disease (COVID-19) infections and its strain on the Campania region's hospitals, in Naples, Italy, March 11, 2021. REUTERS/Ciro de Luca

The seaside walkway 'Lungomare' is closed along with piazzas, as fears rise over the coronavirus disease (COVID-19) infections and its strain on the Campania region's hospitals, in Naples, Italy, March 11, 2021. REUTERS/Ciro de Luca