A Nigerian man, who was repatriated from Saudi Arabia, wearing a protective face mask, looks on upon his arrival at Nnamdi Azikiwe international airport in Abuja, Nigeria January 28, 2021. REUTERS/Afolabi Sotunde

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

A Nigerian woman, who was repatriated from Saudi Arabia, has her temperature checked upon arrival at Nnamdi Azikiwe international airport in Abuja, Nigeria January 28, 2021. REUTERS/Afolabi Sotunde

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

Olga Mikhailova and Vadim Kobzev, lawyers of Russian opposition leader Alexei Navalny, speak to the media after a court hearing to consider an appeal on his arrest outside Moscow, Russia January 28, 2021. REUTERS/Maxim Shemetov

Olga Mikhailova and Vadim Kobzev, lawyers of Russian opposition leader Alexei Navalny, speak to the media after a court hearing to consider an appeal on his arrest outside Moscow, Russia January 28, 2021. REUTERS/Maxim Shemetov

Olga Mikhailova and Vadim Kobzev, lawyers of Russian opposition leader Alexei Navalny, speak to the media after a court hearing to consider an appeal on his arrest outside Moscow, Russia January 28, 2021. REUTERS/Maxim Shemetov

Nigerians, who were repatriated from Saudi Arabia, walk upon their arrival at Nnamdi Azikiwe international airport in Abuja, Nigeria January 28, 2021. REUTERS/Afolabi Sotunde

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson meets troops as they set up a vaccination centre in the Castlemilk district of Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

A Nigerian woman, who was repatriated from Saudi Arabia, has her temperature checked upon arrival at Nnamdi Azikiwe international airport in Abuja, Nigeria January 28, 2021. REUTERS/Afolabi Sotunde

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

Olga Mikhailova and Vadim Kobzev, lawyers of Russian opposition leader Alexei Navalny, speak to the media after a court hearing to consider an appeal on his arrest outside Moscow, Russia January 28, 2021. REUTERS/Maxim Shemetov

Olga Mikhailova and Vadim Kobzev, lawyers of Russian opposition leader Alexei Navalny, speak to the media after a court hearing to consider an appeal on his arrest outside Moscow, Russia January 28, 2021. REUTERS/Maxim Shemetov

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

A woman, part of a group of Nigerian migrants who were repatriated from Saudi Arabia, walks upon her arrival at Nnamdi Azikiwe international airport in Abuja, Nigeria January 28, 2021. REUTERS/Afolabi Sotunde

Nigerian migrants, who were repatriated from Saudi Arabia, are seen upon their arrival at Nnamdi Azikiwe international airport in Abuja, Nigeria January 28, 2021. REUTERS/Afolabi Sotunde

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

A protester gestures from a makeshift camp on a treetop as Extinction Rebellion activists occupy tunnels under Euston Square Gardens to protest against the HS2 high-speed railway, in London, Britain January 28, 2021. REUTERS/Toby Melville

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS

British Prime Minister Boris Johnson is shown the Lighthouse Laboratory used for processing PCR samples, during a visit to the Queen Elizabeth University Hospital campus in Glasgow, Scotland, Britain January 28, 2021. Jeff J Mitchell/Pool via REUTERS