A staff member holds a QR code for the "LeaveHomeSafe" COVID-19 contact-tracing app to consumers at a restaurant, following the coronavirus disease (COVID-19) outbreak, in Hong Kong, China February 18, 2021. REUTERS/Tyrone Siu

QR codes for the "LeaveHomeSafe" COVID-19 contact-tracing app are posted at a restaurant, following the coronavirus disease (COVID-19) outbreak, in Hong Kong, China February 18, 2021. REUTERS/Tyrone Siu

Consumers scan QR codes for the "LeaveHomeSafe" COVID-19 contact-tracing app at a restaurant, following the coronavirus disease (COVID-19) outbreak, in Hong Kong, China February 18, 2021. REUTERS/Tyrone Siu

A staff member holds a QR code for the "LeaveHomeSafe" COVID-19 contact-tracing app to consumers at a restaurant, following the coronavirus disease (COVID-19) outbreak, in Hong Kong, China February 18, 2021. REUTERS/Tyrone Siu

A QR code for the "LeaveHomeSafe" COVID-19 contact-tracing app is posted at a shopping mall, following the coronavirus disease (COVID-19) outbreak, in Hong Kong, China February 16, 2021. REUTERS/Tyrone Siu

A QR code for the "LeaveHomeSafe" COVID-19 contact-tracing app is posted at a shopping mall, following the coronavirus disease (COVID-19) outbreak, in Hong Kong, China February 16, 2021. REUTERS/Tyrone Siu

A QR code for the "LeaveHomeSafe" Covid-19 contact-tracing app is posted during Lunar New Year fair at Victoria Park, following the coronavirus disease (COVID-19) outbreak, in Hong Kong, China February 11, 2021. REUTERS/Tyrone Siu

A QR code for the "LeaveHomeSafe" Covid-19 contact-tracing app is posted during Lunar New Year fair at Victoria Park, following the coronavirus disease (COVID-19) outbreak, in Hong Kong, China February 11, 2021. REUTERS/Tyrone Siu

A mock sample of a QR-coded vaccination pass that will be distributed to all people that receive the vaccine against the coronavirus disease (COVID-19) is pictured in the eastern Bavarian district of Altoetting, Germany February 5, 2021. REUTERS/Marcus Nagle

A mock sample of a QR-coded vaccination pass that will be distributed to all people that receive the vaccine against the coronavirus disease (COVID-19) is pictured in the eastern Bavarian district of Altoetting, Germany February 5, 2021. REUTERS/Marcus Nagle

A mock sample of a QR-coded vaccination pass that will be distributed to all people that receive the vaccine against the coronavirus disease (COVID-19) is pictured in the eastern Bavarian district of Altoetting, Germany February 5, 2021. REUTERS/Marcus Nagle

A chart indicating colour coding systems for different oxygen delivery percentages is seen on a wall in the HDU (High Dependency Unit) at Milton Keynes University Hospital, amid the spread of the coronavirus disease (COVID-19) pandemic, Milton Keynes, Britain, January 20, 2021. Picture taken January 20, 2021. REUTERS/Toby Melville

A screenshot obtained January 20, 2021, shows HTML code on https://www.whitehouse.gov/ containing an invitation to join the U.S. Digital Service, a technology unit within the White House. REUTERS

People show their health code to a man guarding an entry checkpoint of a market as they register their visit, following the new outbreak of the coronavirus disease (COVID-19), in Beijing, China January 15, 2021. REUTERS/Tingshu Wang

A woman scans a health QR code on her smartphone to register her visit to a market before crossing the entry checkpoint, following the new outbreak of the coronavirus disease (COVID-19), in Beijing, China January 15, 2021. REUTERS/Tingshu Wang

People show their health code to a man guarding an entry checkpoint of a market as they register their visit, following the new outbreak of the coronavirus disease (COVID-19), in Beijing, China January 15, 2021. REUTERS/Tingshu Wang

A QR code for passengers to register health information is seen on a plastic shield inside a ride-hailing vehicle, following the coronavirus disease (COVID-19) outbreak in Beijing, China January 14, 2021. REUTERS/Florence Lo

A taxi driver shows a QR code of health registration for a passenger to scan before a ride, following new cases of the coronavirus disease (COVID-19) in the country, in Beijing, China January 11, 2021. REUTERS/Tingshu Wang

People scan a QR code for checking health condition as they enter a market, following new cases of the coronavirus disease (COVID-19) in the country, in Beijing, China January 11, 2021. REUTERS/Tingshu Wang

QR code of the electronic payment service Alipay that belongs to Ant Group Co Ltd is seen at a market stall in Beijing, China, December 31, 2020. REUTERS/Thomas Peter

Customer uses a phone to scan the QR code of the electronic payment service Alipay that belongs to Ant Group Co Ltd at a market stall in Beijing, China, December 31, 2020. REUTERS/Thomas Peter

A security guard directs people to scan a QR code to track their health status before entering a shopping complex, following the new cases of the coronavirus disease (COVID-19) in Beijing, China December 25, 2020. REUTERS/Tingshu Wang

A military aide carries the nuclear launch codes into the White House, after U.S. President Donald Trump arrived from travel to West Point, New York, on the South Lawn in Washington, U.S., December 12, 2020. REUTERS/Cheriss May

A volunteer writes a confirmation code during a popular consultation launched by opposition leader Juan Guaido to reject Venezuela's December 6 parliamentary election, in Doral, Florida, U.S., December 12, 2020. REUTERS/Marco Bello

A man shows a code confirming his digital vote at a voting center for the popular consultation meant to reject December 6 parliamentary election in Caracas, Venezuela December 12, 2020. REUTERS/Manaure Quintero

The mutations that give rise to new strains occur when the SARS-CoV-2 virus makes copies of itself inside a new host. The virus’ genome is a complete set of genetic instructions that is written in 30,000 “letters” of code.

Customers register before entering the restaurant Comedor de los Milagros after the city government implemented a QR-code registration system to prevent novel coronavirus spread in Mexico City, Mexico November 25, 2020. REUTERS/Henry Romero

Customers register before entering the restaurant Comedor de los Milagros after the city government implemented a QR-code registration system to prevent novel coronavirus spread in Mexico City, Mexico November 25, 2020. REUTERS/Henry Romero

A man wearing a face mask walks past signs of the "LeaveHomeSafe" mobile app, a QR health code system to track people's health status amid the coronavirus disease (COVID-19) outbreak, at a building in Hong Kong, China November 25, 2020. REUTERS/Lam Yik

A sign introducing the "LeaveHomeSafe" mobile app, a QR health code system to track people's health status amid the coronavirus disease (COVID-19) outbreak, is seen on a notice board at a building in Hong Kong, China November 25, 2020. REUTERS/Lam Yik

Travellers scan a QR code to track their itinerary history at Beijing Capital International Airport, following the global outbreak of the coronavirus disease (COVID-19), in Beijing, China November 22, 2020. REUTERS/Tingshu Wang

A QR code is seen before a funeral service with social distancing measures due to the coronavirus disease (COVID-19) outbreak, at St Mary's Church in Milton Keynes, Britain, November 18, 2020. REUTERS/Andrew Boyers

A Code Enforcement officer removes a U.S. President Donald Trump and Vice President Mike Pence campaign sign from the entrance of a polling station during the 2020 U.S. presidential election in Palm Beach, Florida, U.S., November 3, 2020. REUTERS/Marco Bello

A Code Enforcement officer asks to a supporter to stop placing U.S. President Donald Trump and Vice President Mike Pence campaign signs in the limits of a polling station during the 2020 U.S. presidential election in Palm Beach, Florida, U.S., November 3, 2020. REUTERS/Marco Bello TPX IMAGES OF THE DAY

A QR code of digital payment device Alipay by Ant Group, an affiliate of Alibaba Group Holding, is seen at a watch repair shop inside a market, in Beijing, China November 2, 2020. REUTERS/Tingshu Wang

A QR code of digital payment device Alipay by Ant Group, an affiliate of Alibaba Group Holding, is seen at a grocery shop inside a market, in Beijing, China November 2, 2020. REUTERS/Tingshu Wang

A QR code of digital payment device Alipay by Ant Group, an affiliate of Alibaba Group Holding, is seen at a food stall inside a market, in Beijing, China November 2, 2020. REUTERS/Tingshu Wang

A QR code of digital payment device Alipay by Ant Group, an affiliate of Alibaba Group Holding, is seen next to a QR code of WeChat Pay at a food stall inside a market, in Beijing, China November 2, 2020. REUTERS/Tingshu Wang

A QR code of digital payment device Alipay by Ant Group, an affiliate of Alibaba Group Holding, is seen at a food stall inside a market, in Beijing, China November 2, 2020. REUTERS/Tingshu Wang

A QR code of digital payment device Alipay by Ant Group, an affiliate of Alibaba Group Holding, is seen at a grocery shop inside a market, in Beijing, China November 2, 2020. REUTERS/Tingshu Wang

A person gets a scan of a phone's QR code of the digital payment services at a food shop, following the coronavirus disease (COVID-19) outbreak, in Shanghai, China October 10, 2020. REUTERS/Aly Song

A QR code of the digital payment service WeChat Pay is seen at a shop, following the coronavirus disease (COVID-19) outbreak, in Shanghai, China October 10, 2020. REUTERS/Aly Song

A woman gets her phone's QR code of the digital payment services scanned at a food shop, following the coronavirus disease (COVID-19) outbreak, in Shanghai, China October 10, 2020. REUTERS/Aly Song

A woman gets her phone's QR code of the digital payment services scanned at a food shop, following the coronavirus disease (COVID-19) outbreak, in Shanghai, China October 10, 2020. REUTERS/Aly Song

A woman gets her phone's QR code of the digital payment services scanned at a food shop, following the coronavirus disease (COVID-19) outbreak, in Shanghai, China October 10, 2020. REUTERS/Aly Song

A QR code for the NHS coronavirus app is seen next to a hand sanitiser dispenser outside a bar following the outbreak of the coronavirus disease (COVID-19) in Manchester, Britain, October 5, 2020. REUTERS/Phil Noble

White House aides, including the military aide carrying the nuclear launch codes known as "the nuclear football," follow U.S. President Donald Trump as he boards the Marine One helicopter to depart the White House and fly to Walter Reed National Military Medical Center, where it was announced he will stay for at least several days after testing positive for the coronavirus disease (COVID-19), on the South Lawn of the White House in Washington, U.S., October 2, 2020. REUTERS/Leah Millis

A woman takes a picture of giant QR code that promotes the new NHS COVID-19 app and it is placed next to the entrance of the MK Gallery, amid the spread of the coronavirus disease (COVID-19) in Milton Keynes, Britain September 25, 2020. REUTERS/Andrew Boyers

A giant QR code that promotes the new NHS COVID-19 app is placed next to the entrance of the MK Gallery, amid the spread of the coronavirus disease (COVID-19) in Milton Keynes, Britain September 25, 2020. REUTERS/Andrew Boyers

A giant QR code that promotes the new NHS COVID-19 app is placed next to the entrance of the MK Gallery, amid the spread of the coronavirus disease (COVID-19) in Milton Keynes, Britain September 25, 2020. REUTERS/Andrew Boyers

A giant QR code that promotes the new NHS COVID-19 app is placed next to the entrance of the MK Gallery, amid the spread of the coronavirus disease (COVID-19) in Milton Keynes, Britain September 25, 2020. REUTERS/Andrew Boyers

People scan a QR code to check their health before entering the Seasons Place Shopping Mall at the Beijing Financial Street, following the coronavirus disease (COVID-19) outbreak, in Beijing, China September 23, 2020. REUTERS/Tingshu Wang

QR codes for WeChat Pay and Alipay are seen at a market in Beijing, China September 18, 2020. REUTERS/Tingshu Wang

A customer scans a QR code to access the Andres Carne de Res restaurant menu, amidst the coronavirus disease (COVID-19) outbreak, in Chia, Colombia August 30, 2020. Picture taken August 30, 2020. REUTERS/Luisa Gonzalez

A staff member holds a thermometer for temperature checks as he requires people to scan a health code at the entrance of the Maple Garden Drive-in Cinema, during Beijing International Film Festival following the coronavirus disease (COVID-19) outbreak, in Beijing, China August 24, 2020. REUTERS/Tingshu Wang

A staff member checks people's health code as they enter the Maple Garden Drive-in Cinema for an outdoor movie projection during Beijing International Film Festival, following the coronavirus disease (COVID-19) outbreak, in Beijing, China August 24, 2020. REUTERS/Tingshu Wang

A worker scans a WeChat Pay QR code to buy a takeaway meal for lunch near a construction site, following the coronavirus disease (COVID-19) outbreak, in Beijing, China August 21, 2020. REUTERS/Tingshu Wang

QR codes of the digital payment services WeChat Pay and its competitor Alipay are seen at a meat stall at a fresh market in Beijing, China August 8, 2020. REUTERS/Thomas Peter

A person scans the QR code of the digital payment services WeChat Pay at a fresh market in Beijing, China August 8, 2020. REUTERS/Thomas Peter

A QR code of the digital payment services WeChat Pay is seen at a fish monger at a fresh market in Beijing, China August 8, 2020. REUTERS/Thomas Peter