Austrian army members and volunteers wait during a rapid antigen test before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

Austrian army members and volunteers perform a rapid antigen test before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

Austrian army members and volunteers perform a rapid antigen test before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

A health care worker collects a swab sample from a man during a rapid antigen test for army members and volunteers before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

Austrian army members wait during a rapid antigen test before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

Austrian army members and volunteers perform a rapid antigen test before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

Austrian army members and volunteers perform a rapid antigen test before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

A passenger walks past a testing centre sign in the terminal building of Manchester Airport amid the outbreak of the coronavirus disease (COVID-19) in Manchester, Britain, December 3, 2020. REUTERS/Phil Noble

A passenger walks past a testing centre sign in the terminal building of Manchester Airport amid the outbreak of the coronavirus disease (COVID-19) in Manchester, Britain, December 3, 2020. REUTERS/Phil Noble

A passenger walks past a testing centre outside the terminal building of Manchester Airport amid the outbreak of the coronavirus disease (COVID-19) in Manchester, Britain, December 3, 2020. REUTERS/Phil Noble

Passengers sit beneath a testing centre sign in the terminal building of Manchester Airport amid the outbreak of the coronavirus disease (COVID-19) in Manchester, Britain, December 3, 2020. REUTERS/Phil Noble

A passenger walks past a testing centre outside the terminal building of Manchester Airport amid the outbreak of the coronavirus disease (COVID-19) in Manchester, Britain, December 3, 2020. REUTERS/Phil Noble

Austrian army members and volunteers perform a rapid antigen test before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

Austrian army members and volunteers perform a rapid antigen test before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

People are reflected in the window of a testing centre outside the terminal building of Manchester Airport amid the outbreak of the coronavirus disease (COVID-19) in Manchester, Britain, December 3, 2020. REUTERS/Phil Noble

People are reflected in the window of a testing centre outside the terminal building of Manchester Airport amid the outbreak of the coronavirus disease (COVID-19) in Manchester, Britain, December 3, 2020. REUTERS/Phil Noble

Austrian army members and volunteers perform a rapid antigen test before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

A passenger walks past a testing centre outside the terminal building of Manchester Airport amid the outbreak of the coronavirus disease (COVID-19) in Manchester, Britain, December 3, 2020. REUTERS/Phil Noble

Nurse David Spicer carries out a test on a member of staff at a testing centre outside the terminal building of Manchester Airport amid the outbreak of the coronavirus disease (COVID-19) in Manchester, Britain, December 3, 2020. REUTERS/Phil Noble

Nurse David Spicer carries out a test on a member of staff at a testing centre outside the terminal building of Manchester Airport amid the outbreak of the coronavirus disease (COVID-19) in Manchester, Britain, December 3, 2020. REUTERS/Phil Noble

Testing centre signage is seen outside the terminal building of Manchester Airport amid the outbreak of the coronavirus disease (COVID-19) in Manchester, Britain, December 3, 2020. REUTERS/Phil Noble

Austrian army members and volunteers perform a rapid antigen test before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

Lori Spencer visits her mom Judie Shape, 81, who Spencer says has tested positive for COVID-19, at Life Care Center of Kirkland, the Seattle-area nursing home, during the coronavirus disease (COVID-19) outbreak in the United States, in Kirkland, Washington, U.S. March 11, 2020. REUTERS/Jason Redmond/File Photo TPX IMAGES OF THE DAY SEARCH "GLOBAL COVID-19" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

A health care worker collects a swab sample from a man during a rapid antigen test for army members and volunteers before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

A health care worker collects a swab sample from a man during a rapid antigen test for army members and volunteers before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

An aerial view of vehicles waiting at a drive-thru COVID-19 testing site in the parking lot of Miller Park, during the coronavirus disease (COVID-19) outbreak, in Milwaukee, Wisconsin, U.S., November 5, 2020. Picture taken with a drone. REUTERS/Bing Guan/File Photo TPX IMAGES OF THE DAY SEARCH "GLOBAL COVID-19" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

A medical worker collects a sample from a woman at a school which was turned into a centre to conduct tests for COVID-19, during the coronavirus disease (COVID-19) outbreak, in New Delhi, India, June 22, 2020. REUTERS/Adnan Abidi/File Photo TPX IMAGES OF THE DAY SEARCH "GLOBAL COVID-19" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES

A health care worker collects a swab sample during a rapid antigen test for army members and volunteers before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

A health care worker waits during a rapid antigen test for army members and volunteers before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

Austrian Health Minister Rudolf Anschober and Interior Minister Karl Nehammer, wearing protective face masks inspect a rapid antigen test before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

A health care worker collects a swab sample from a man during a rapid antigen test for army members and volunteers before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

A health care worker collects a swab sample from a man during a rapid antigen test for army members and volunteers before the start of a mass test of Vienna's population, as the spread of the coronavirus disease (COVID-19) continues, in Vienna, Austria, December 3, 2020. REUTERS/Leonhard Foeger

Lauren Louks, 24, is given a PCR coronavirus test, as the global outbreak of the coronavirus disease (COVID-19) continues, in Malibu, California, U.S., December 2, 2020. REUTERS/Lucy Nicholson

Wayne Ribnick, 69, is given a PCR coronavirus test, as the global outbreak of the coronavirus disease (COVID-19) continues, in Malibu, California, U.S., December 2, 2020. REUTERS/Lucy Nicholson

Hugo Boserup, 22, is given a PCR coronavirus test, as the global outbreak of the coronavirus disease (COVID-19) continues, in Malibu, California, U.S., December 2, 2020. REUTERS/Lucy Nicholson

PCR coronavirus tests are seen at a testing site, as the global outbreak of the coronavirus disease (COVID-19) continues, in Malibu, California, U.S., December 2, 2020. REUTERS/Lucy Nicholson

Hugo Boserup, 22, is given a PCR coronavirus test, as the global outbreak of the coronavirus disease (COVID-19) continues, in Malibu, California, U.S., December 2, 2020. REUTERS/Lucy Nicholson

Alex Vazquez, 42, is given a PCR coronavirus test, as the global outbreak of the coronavirus disease (COVID-19) continues, in Malibu, California, U.S., December 2, 2020. REUTERS/Lucy Nicholson

Selin Minas, 37, is given a PCR coronavirus test, as the global outbreak of the coronavirus disease (COVID-19) continues, in Malibu, California, U.S., December 2, 2020. REUTERS/Lucy Nicholson

Alex Vazquez, 42, is given a PCR coronavirus test, as the global outbreak of the coronavirus disease (COVID-19) continues, in Malibu, California, U.S., December 2, 2020. REUTERS/Lucy Nicholson

A traveler passes a COVID-19 testing sign as she arrives into the United States through the pedestrian entry at the San Ysidro - Tijuana, Mexico, border crossing during the outbreak of the coronavirus disease, in San Diego, California, U.S., December 2, 2020. REUTERS/Mike Blake

Travelers pass a COVID-19 testing sign as they arrive into the United States through the pedestrian entry at the San Ysidro - Tijuana, Mexico, border crossing during the outbreak of the coronavirus disease, in San Diego, California, U.S., December 2, 2020. REUTERS/Mike Blake

Travelers pass a COVID-19 testing sign as they arrive into the United States through the pedestrian entry at the San Ysidro - Tijuana, Mexico, border crossing during the outbreak of the coronavirus disease, in San Diego, California, U.S., December 2, 2020. REUTERS/Mike Blake

Resident Theresa Snelling hugs her daughter Serena as they are allowed to visit with physical contact for the first time at The Chiswick Nursing Centre, which has introduced a coronavirus disease (COVID-19) test with results ready in thirty minutes, in London, Britain December 2, 2020. REUTERS/Kevin Coombs

Resident Theresa Snelling hugs her daughter Serena as they are allowed to visit with physical contact for the first time at The Chiswick Nursing Centre, which has introduced a coronavirus disease (COVID-19) test with results ready in thirty minutes, in London, Britain December 2, 2020. REUTERS/Kevin Coombs

A healthcare worker wearing protective equipment holds a sign during a mass coronavirus disease (COVID-19) testing to allow students home for Christmas, at the Sports Hall of Keele University, in Keele, Staffordshire, Britain December 2, 2020. REUTERS/Carl Recine

Resident Theresa Snelling hugs her daughter Serena as they are allowed to visit with physical contact for the first time at The Chiswick Nursing Centre, which has introduced a coronavirus disease (COVID-19) test with results ready in thirty minutes, in London, Britain December 2, 2020. REUTERS/Kevin Coombs

Resident Theresa Snelling hugs her daughter Serena as they are allowed to visit with physical contact for the first time at The Chiswick Nursing Centre, which has introduced a coronavirus disease (COVID-19) test with results ready in thirty minutes, in London, Britain December 2, 2020. REUTERS/Kevin Coombs

Booths for testing are pictured at the Sports Hall of Keele University during a mass coronavirus disease (COVID-19) testing to allow students home for Christmas, in Keele, Staffordshire, Britain December 2, 2020. REUTERS/Carl Recine

A general view shows the Sports Hall of Keele University during a mass coronavirus disease (COVID-19) testing to allow students home for Christmas, in Keele, Staffordshire, Britain December 2, 2020. REUTERS/Carl Recine

A healthcare worker wearing protective equipment is seen as a person gives a swab sample during a mass coronavirus disease (COVID-19) testing to allow students home for Christmas, at the Sports Hall of Keele University, in Keele, Staffordshire, Britain December 2, 2020. REUTERS/Carl Recine

Healthcare workers stand during a mass coronavirus disease (COVID-19) testing to allow students home for Christmas, at the Sports Hall of Keele University, in Keele, Staffordshire, Britain December 2, 2020. REUTERS/Carl Recine

A healthcare worker wearing protective equipment is seen as a person gives a swab sample during a mass coronavirus disease (COVID-19) testing to allow students home for Christmas, at the Sports Hall of Keele University, in Keele, Staffordshire, Britain December 2, 2020. REUTERS/Carl Recine

People give swab samples during a mass coronavirus disease (COVID-19) testing to allow students home for Christmas, at the Sports Hall of Keele University, in Keele, Staffordshire, Britain December 2, 2020. REUTERS/Carl Recine

A healthcare worker wearing protective equipment looks at a person giving a swab sample during a mass coronavirus disease (COVID-19) testing to allow students home for Christmas, at the Sports Hall of Keele University, in Keele, Staffordshire, Britain December 2, 2020. REUTERS/Carl Recine

A person gives a swab sample during a mass coronavirus disease (COVID-19) testing to allow students home for Christmas, at the Sports Hall of Keele University, in Keele, Staffordshire, Britain December 2, 2020. REUTERS/Carl Recine

A person gives a swab sample during a mass coronavirus disease (COVID-19) testing to allow students home for Christmas, at the Sports Hall of Keele University, in Keele, Staffordshire, Britain December 2, 2020. REUTERS/Carl Recine

Bob Underhill, 84, meets with his wife Patricia, 82, suffering from Alzheimer's, as they are allowed to visit with physical contact for the first time at The Chiswick Nursing Centre, which has introduced a coronavirus disease (COVID-19) test with results ready in thirty minutes, in London, Britain December 2, 2020. REUTERS/Kevin Coombs

Bob Underhill, 84, and his wife Patricia, 82, suffering from Alzheimer's, kiss through a face mask as they are allowed to visit with physical contact for the first time at The Chiswick Nursing Centre, which has introduced a coronavirus disease (COVID-19) test with results ready in thirty minutes, in London, Britain December 2, 2020. REUTERS/Kevin Coombs

Bob Underhill, 84, meets with his wife Patricia, 82, suffering from Alzheimer's, as they are allowed to visit with physical contact for the first time at The Chiswick Nursing Centre, which has introduced a coronavirus disease (COVID-19) test with results ready in thirty minutes, in London, Britain December 2, 2020. REUTERS/Kevin Coombs