A person receives a dose of China's Sinopharm coronavirus disease (COVID-19) vaccine at a sport centre, as the country continues its mass inoculation campaign, in Stip, North Macedonia May 6, 2021. REUTERS/Ognen Teofilovski

People rest after receiving a dose of China's Sinopharm coronavirus disease (COVID-19) vaccine at a sport centre, as the country continues its mass inoculation campaign, in Stip, North Macedonia May 6, 2021. REUTERS/Ognen Teofilovski

A healthcare worker handles China's Sinopharm coronavirus disease (COVID-19) vaccines at a sport centre, as the country continues its mass inoculation campaign, in Stip, North Macedonia May 6, 2021. REUTERS/Ognen Teofilovski

A healthcare worker handles China's Sinopharm coronavirus disease (COVID-19) vaccines at a sport centre, as the country continues its mass inoculation campaign, in Stip, North Macedonia May 6, 2021. REUTERS/Ognen Teofilovski

A healthcare worker handles China's Sinopharm coronavirus disease (COVID-19) vaccines at a sport centre, as the country continues its mass inoculation campaign, in Stip, North Macedonia May 6, 2021. REUTERS/Ognen Teofilovski

A healthcare worker handles China's Sinopharm coronavirus disease (COVID-19) vaccines at a sport centre, as the country continues its mass inoculation campaign, in Stip, North Macedonia May 6, 2021. REUTERS/Ognen Teofilovski

People wait to get shots of vaccines against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

A woman gets a shot of vaccine against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

People wait to get shots of vaccines against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

People wait to get shots of vaccines against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

People wait to get shots of vaccines against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

People wait to get shots of vaccines against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

People wait to get shots of vaccines against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

People wait to get shots of vaccines against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

People wait to get shots of vaccines against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

People wait to get shots of vaccines against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

People wait to get shots of vaccines against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica TPX IMAGES OF THE DAY

People wait to get shots of vaccines against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

A woman gets a shot of vaccine against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

A woman gets a shot of vaccine against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

People wait to get shots of vaccines against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

Vials of Sinopharm, Sputnik V and Pfizer-BioNTech vaccines against the coronavirus disease (COVID-19) are seen in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

People wait to get shots of vaccines against the coronavirus disease (COVID-19) in the Usce shopping mall, where the first 100 vaccinated will receive a discount voucher worth 3,000 dinars ($30.74) secured by mall's management and retailers, in Belgrade, Serbia, May 6, 2021. REUTERS/Marko Djurica

A 3D-printed Telegram app logo, small toy figurines, a syringe and vial labelled "coronavirus disease (COVID-19) vaccine" are seen in front of India flag in this illustration taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A 3D-printed Telegram app logo and small toy figurines are seen in front of India flag in this illustration taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

3D-printed small toy figurines, a syringe and vial labelled "coronavirus disease (COVID-19) vaccine" are seen in front of India flag in this illustration taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A 3D-printed Telegram app logo and vials labelled "coronavirus disease (COVID-19) vaccine" are seen in front of India flag in this illustration taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

3D-printed small toy figurines are seen in front of India flag in this illustration taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A 3D-printed Telegram app logo, a syringe and vial labelled "coronavirus disease (COVID-19) vaccine" are seen in front of India flag in this illustration taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A 3D-printed Telegram app logo, a syringe and vials labelled "coronavirus disease (COVID-19) vaccine" are seen in front of India flag in this illustration taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

Representation of virtual currency Bitcoin and a padlock are placed on a computer motherboard in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

Mastercard credit cards and a padlock are placed on a computer motherboard in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

Visa credit cards and a padlock are seen placed on a computer motherboard in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A padlock is hooked on a credit card and placed on a keyboard in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

Padlock is hooked on a credit card and placed on a computer motherboard in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A 3D printed Apple TV logo is seen in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A 3D printed Facebook logo and a padlock are placed on a computer motherboard in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A padlock is placed on a computer motherboard in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A 3D printed Twitter logo and a padlock are placed on a computer motherboard in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A 3D printed Android logo is seen in front of a padlock in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A 3D printed Whatsapp logo and a padlock are placed on a computer motherboard in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A 3D printed Zoom logo is seen behind a padlock in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A 3D printed Twitter logo is seen behind a padlock in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A 3D printed Facebook logo is seen in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A 3D printed Facebook logo is seen behind a padlock in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A 3D printed Facebook logo is seen in front of a padlock in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

A 3D printed Facebook logo is seen in front of padlocks in this illustration picture taken May 4, 2021. REUTERS/Dado Ruvic/Illustration

Doses of the Chinese Sinopharm vaccine against the coronavirus disease (COVID-19) are seen at a restaurant in Kragujevac, Serbia, May 4, 2021. At the Biblioteka kod Milutina restaurant whoever decides to get vaccinated is served a free meal on Tuesday, as a one-time offer to promote vaccination and contribute to the reopening of cafes, restaurants and bars. REUTERS/Marko Djurica

Doses of the Chinese Sinopharm vaccine against the coronavirus disease (COVID-19) are seen at a restaurant in Kragujevac, Serbia, May 4, 2021. At the Biblioteka kod Milutina restaurant whoever decides to get vaccinated is served a free meal on Tuesday, as a one-time offer to promote vaccination and contribute to the reopening of cafes, restaurants and bars. REUTERS/Marko Djurica

Doses of the Chinese Sinopharm vaccine against the coronavirus disease (COVID-19) are seen at a restaurant in Kragujevac, Serbia, May 4, 2021. At the Biblioteka kod Milutina restaurant whoever decides to get vaccinated is served a free meal on Tuesday, as a one-time offer to promote vaccination and contribute to the reopening of cafes, restaurants and bars. REUTERS/Marko Djurica

Doses of the Chinese Sinopharm vaccine against the coronavirus disease (COVID-19) are seen at a restaurant in Kragujevac, Serbia, May 4, 2021. At the Biblioteka kod Milutina restaurant whoever decides to get vaccinated is served a free meal on Tuesday, as a one-time offer to promote vaccination and contribute to the reopening of cafes, restaurants and bars. REUTERS/Marko Djurica

A man receives a dose of the Chinese Sinopharm vaccine against the coronavirus disease (COVID-19) at restaurant in Kragujevac, Serbia, May 4, 2021. At the Biblioteka kod Milutina restaurant whoever decides to get vaccinated is served a free meal on Tuesday, as a one-time offer to promote vaccination and contribute to the reopening of cafes, restaurants and bars. REUTERS/Marko Djurica

Customers have their meals at a restaurant where people are receiving doses of the Chinese Sinopharm vaccine against the coronavirus disease (COVID-19) in Kragujevac, Serbia, May 4, 2021. At the Biblioteka kod Milutina restaurant whoever decides to get vaccinated is served a free meal on Tuesday, as a one-time offer to promote vaccination and contribute to the reopening of cafes, restaurants and bars. REUTERS/Marko Djurica

An ox is roasted in front of a restaurant where people are receiving doses of the Chinese Sinopharm vaccine against the coronavirus disease (COVID-19) in Kragujevac, Serbia, May 4, 2021. At the Biblioteka kod Milutina restaurant whoever decides to get vaccinated is served a free meal on Tuesday, as a one-time offer to promote vaccination and contribute to the reopening of cafes, restaurants and bars. REUTERS/Marko Djurica

A man prepares roasted ox in front of a restaurant where people are receiving doses of the Chinese Sinopharm vaccine against the coronavirus disease (COVID-19) in Kragujevac, Serbia, May 4, 2021. At the Biblioteka kod Milutina restaurant whoever decides to get vaccinated is served a free meal on Tuesday, as a one-time offer to promote vaccination and contribute to the reopening of cafes, restaurants and bars. REUTERS/Marko Djurica

People wait to receive doses of the Chinese Sinopharm vaccine against the coronavirus disease (COVID-19) at restaurant in Kragujevac, Serbia, May 4, 2021. At the Biblioteka kod Milutina restaurant whoever decides to get vaccinated is served a free meal on Tuesday, as a one-time offer to promote vaccination and contribute to the reopening of cafes, restaurants and bars. REUTERS/Marko Djurica REFILE - CORRECTING MONTH


A man prepares to receive a dose of the Chinese Sinopharm vaccine against the coronavirus disease (COVID-19) at restaurant in Kragujevac, Serbia, May 4, 2021. At the Biblioteka kod Milutina restaurant whoever decides to get vaccinated is served a free meal on Tuesday, as a one-time offer to promote vaccination and contribute to the reopening of cafes, restaurants and bars. REUTERS/Marko Djurica REFILE - CORRECTING MONTH


A woman prepares to receive a dose of the Chinese Sinopharm vaccine against the coronavirus disease (COVID-19) at restaurant in Kragujevac, Serbia, May 4, 2021. At the Biblioteka kod Milutina restaurant whoever decides to get vaccinated is served a free meal on Tuesday, as a one-time offer to promote vaccination and contribute to the reopening of cafes, restaurants and bars. REUTERS/Marko Djurica REFILE - CORRECTING MONTH

People wait to receive doses of the Chinese Sinopharm vaccine against the coronavirus disease (COVID-19) at a restaurant in Kragujevac, Serbia, May 4, 2021. At the Biblioteka kod Milutina restaurant whoever decides to get vaccinated is served a free meal on Tuesday, as a one-time offer to promote vaccination and contribute to the reopening of cafes, restaurants and bars. REUTERS/Marko Djurica REFILE - CORRECTING MONTH


A man receives a dose of the Chinese Sinopharm vaccine against the coronavirus disease (COVID-19) at a restaurant in Kragujevac, Serbia, May 4, 2021. At the Biblioteka kod Milutina restaurant whoever decides to get vaccinated is served a free meal on Tuesday, as a one-time offer to promote vaccination and contribute to the reopening of cafes, restaurants and bars. REUTERS/Marko Djurica REFILE - CORRECTING MONTH