A patient suffering from the coronavirus disease (COVID-19) is seen at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

A medical worker treats patients suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

Medical workers treat a patient suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

A medical worker is seen after treating patients suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

Medical workers treat a patient suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

Medical workers treat a patient suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

A patient suffering from the coronavirus disease (COVID-19) is seen at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

A patient suffering from the coronavirus disease (COVID-19) is seen at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

A medical worker treats a patient suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

Patients suffering from the coronavirus disease (COVID-19) are seen at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

Medical workers test a man for the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

People wait for testing for the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

A medical worker is seen after treating patients suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

People wait for testing for the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

A patient suffering from the coronavirus disease (COVID-19) is seen at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

A medical worker treats patients suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

Medical workers treat patients suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

Medical workers treat patients suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

Medical workers treat patients suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

A medical worker treats a patient suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

A medical worker treats a patient suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

Medical workers treat a patient suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

Medical worker is seen after treating patients suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

A medical worker treats a patient suffering from the coronavirus disease (COVID-19) at Clinical Hospital Center Zemun in Belgrade, Serbia, November 26, 2020. REUTERS/Marko Djurica

Miomir Korac, lead archaeologist, poses for a picture at the remains of Roman legion's headquarters at the ancient city of Viminacium, near Kostolac, Serbia, November 25, 2020. Picture taken November 25, 2020. REUTERS/Marko Djurica

An archaeologist excavates the remains of Roman legion's headquarters at the ancient city of Viminacium, near Kostolac, Serbia, November 25, 2020. Picture taken November 25, 2020. REUTERS/Marko Djurica

Silver coins found at the remains of a Roman legion's headquarters are seen at the ancient city of Viminacium, near Kostolac, Serbia, November 25, 2020. Picture taken November 25, 2020. REUTERS/Marko Djurica

Archaeologists excavate the remains of Roman legion's headquarters at the ancient city of Viminacium, near Kostolac, Serbia, November 25, 2020. Picture taken November 25, 2020. REUTERS/Marko Djurica

Archaeologists excavate the remains of Roman legion's headquarters at the ancient city of Viminacium, near Kostolac, Serbia, November 25, 2020. Picture taken November 25, 2020. REUTERS/Marko Djurica

Archaeologists excavate the remains of Roman legion's headquarters at the ancient city of Viminacium, near Kostolac, Serbia, November 25, 2020. Picture taken November 25, 2020. Picture taken with a drone. REUTERS/Marko Djurica

Archaeologists excavate the remains of Roman legion's headquarters at the ancient city of Viminacium, near Kostolac, Serbia, November 25, 2020. Picture taken November 25, 2020. Picture taken with a drone. REUTERS/Marko Djurica

Archaeologists excavate the remains of Roman legion's headquarters at the ancient city of Viminacium, near Kostolac, Serbia, November 25, 2020. Picture taken November 25, 2020. Picture taken with a drone. REUTERS/Marko Djurica

Archaeologists excavate the remains of Roman legion's headquarters at the ancient city of Viminacium, near Kostolac, Serbia, November 25, 2020. Picture taken November 25, 2020. Picture taken with a drone. REUTERS/Marko Djurica

Youth rides his bike along a pedestrian street in downtown Belgrade, Serbia, November 23, 2020. REUTERS/Marko Djurica

Woman poses next to a Christmas decoration, during the COVID-19 pandemic in downtown Belgrade, Serbia, November 23, 2020. REUTERS/Marko Djurica

Reza, an 18-year-old Afghan migrant, draws at an art studio in Belgrade, Serbia, November 21, 2020. Unlike throngs of migrants from the Middle East and Asia which since 2015 passed through the Balkans to reach Western Europe, Reza decided to stay in Serbia where he was granted asylum. Reza arrived to Serbia from Iran in 2017 as an unaccompanied minor and now he is studying to become an artist. Picture taken November 21, 2020. REUTERS/Marko Djurica

Reza, an 18-year-old Afghan migrant, poses for a picture at an art studio in Belgrade, Serbia, November 21, 2020. Unlike throngs of migrants from the Middle East and Asia which since 2015 passed through the Balkans to reach Western Europe, Reza decided to stay in Serbia where he was granted asylum. Reza arrived to Serbia from Iran in 2017 as an unaccompanied minor and now he is studying to become an artist. Picture taken November 21, 2020. REUTERS/Marko Djurica

Reza, an 18-year-old Afghan migrant, poses for a picture outside an art studio in Belgrade, Serbia, November 21, 2020. Unlike throngs of migrants from the Middle East and Asia which since 2015 passed through the Balkans to reach Western Europe, Reza decided to stay in Serbia where he was granted asylum. Reza arrived to Serbia from Iran in 2017 as an unaccompanied minor and now he is studying to become an artist. Picture taken November 21, 2020. REUTERS/Marko Djurica

Reza, an 18-year-old Afghan migrant, poses for a picture outside an art studio in Belgrade, Serbia, November 21, 2020. Unlike throngs of migrants from the Middle East and Asia which since 2015 passed through the Balkans to reach Western Europe, Reza decided to stay in Serbia where he was granted asylum. Reza arrived to Serbia from Iran in 2017 as an unaccompanied minor and now he is studying to become an artist. Picture taken November 21, 2020. REUTERS/Marko Djurica

Reza, an 18-year-old Afghan migrant, draws at an art studio in Belgrade, Serbia, November 21, 2020. Unlike throngs of migrants from the Middle East and Asia which since 2015 passed through the Balkans to reach Western Europe, Reza decided to stay in Serbia where he was granted asylum. Reza arrived to Serbia from Iran in 2017 as an unaccompanied minor and now he is studying to become an artist. Picture taken November 21, 2020. REUTERS/Marko Djurica

Reza, an 18-year-old Afghan migrant, takes a break at an art studio in Belgrade, Serbia, November 21, 2020. Unlike throngs of migrants from the Middle East and Asia which since 2015 passed through the Balkans to reach Western Europe, Reza decided to stay in Serbia where he was granted asylum. Reza arrived to Serbia from Iran in 2017 as an unaccompanied minor and now he is studying to become an artist. Picture taken November 21, 2020. REUTERS/Marko Djurica

Reza, an 18-year-old Afghan migrant, draws at an art studio in Belgrade, Serbia, November 21, 2020. Unlike throngs of migrants from the Middle East and Asia which since 2015 passed through the Balkans to reach Western Europe, Reza decided to stay in Serbia where he was granted asylum. Reza arrived to Serbia from Iran in 2017 as an unaccompanied minor and now he is studying to become an artist. Picture taken November 21, 2020. REUTERS/Marko Djurica

Reza, an 18-year-old Afghan migrant, draws at an art studio in Belgrade, Serbia, November 21, 2020. Unlike throngs of migrants from the Middle East and Asia which since 2015 passed through the Balkans to reach Western Europe, Reza decided to stay in Serbia where he was granted asylum. Reza arrived to Serbia from Iran in 2017 as an unaccompanied minor and now he is studying to become an artist. Picture taken November 21, 2020. REUTERS/Marko Djurica

Serbian gendarmerie officers stand guard during the funeral of Serbia's late Patriarch Irinej, who died of the coronavirus disease (COVID-19), in front of Belgrade's St. Sava templein Belgrade, Serbia, November 22, 2020. REUTERS/Marko Djurica

Mourners attend the funeral of Serbia's late Patriarch Irinej, who died of the coronavirus disease (COVID-19), in front of Belgrade's St. Sava templein Belgrade, Serbia, November 22, 2020. REUTERS/Marko Djurica

Mourners attend the funeral of Serbia's late Patriarch Irinej, who died of the coronavirus disease (COVID-19), in front of Belgrade's St. Sava templein Belgrade, Serbia, November 22, 2020. REUTERS/Marko Djurica

Mourners attend the funeral of Serbia's late Patriarch Irinej, who died of the coronavirus disease (COVID-19), in front of Belgrade's St. Sava templein Belgrade, Serbia, November 22, 2020. REUTERS/Marko Djurica

Mourners attend the funeral of Serbia's late Patriarch Irinej, who died of the coronavirus disease (COVID-19), in front of Belgrade's St. Sava templein Belgrade, Serbia, November 22, 2020. REUTERS/Marko Djurica

Mourners pay their respect near the casket of Serbia's late Patriarch Irinej, who died of the coronavirus disease (COVID-19), during funeral rites at Belgrade's St. Sava temple, in Belgrade, Serbia, November 22, 2020. REUTERS/Marko Djurica

Priests stand by the casket of Serbia's late Patriarch Irinej, who died of the coronavirus disease (COVID-19), during funeral rites at Belgrade's St. Sava temple, in Belgrade, Serbia, November 22, 2020. REUTERS/Marko Djurica

Serbian President Aleksandar Vucic pays his respect by the casket of Serbia's late Patriarch Irinej, who died of the coronavirus disease (COVID-19), during funeral rites at Belgrade's St. Sava temple, in Belgrade, Serbia, November 22, 2020. REUTERS/Marko Djurica

Serbian President Aleksandar Vucic pays his respect by the casket of Serbia's late Patriarch Irinej, who died of the coronavirus disease (COVID-19), during funeral rites at Belgrade's St. Sava temple, in Belgrade, Serbia, November 22, 2020. REUTERS/Marko Djurica

Serbian President Aleksandar Vucic pays his respect by the casket of Serbia's late Patriarch Irinej, who died of the coronavirus disease (COVID-19), during funeral rites at Belgrade's St. Sava temple, in Belgrade, Serbia, November 22, 2020. REUTERS/Marko Djurica

Serbian President Aleksandar Vucic pays his respect by the casket of Serbia's late Patriarch Irinej, who died of the coronavirus disease (COVID-19), during funeral rites at Belgrade's St. Sava temple, in Belgrade, Serbia, November 22, 2020. REUTERS/Marko Djurica

Priests stand by the casket of Serbia's late Patriarch Irinej, who died of the coronavirus disease (COVID-19), during funeral rites at Belgrade's St. Sava temple, in Belgrade, Serbia, November 22, 2020. REUTERS/Marko Djurica

Serbian Army guardsmen stand next to the casket of Serbia's late Patriarch Irinej, who died of coronavirus infection, during funeral rites at Belgrade's St. Sava temple, in Belgrade, Serbia, November 21, 2020. REUTERS/Marko Djurica

Serbian Army guardsmen carry the casket of Serbia's late Patriarch Irinej, who died of coronavirus infection, during funeral rites at Belgrade's St. Sava temple, in Belgrade, Serbia, November 21, 2020. REUTERS/Marko Djurica

Mourners pay their respect over the casket of Serbia's late Patriarch Irinej, who died of coronavirus infection, during funeral rites at Belgrade's St. Sava temple, in Belgrade, Serbia, November 21, 2020. REUTERS/Marko Djurica

Priests pay their respect over the casket of Serbia's late Patriarch Irinej, who died of coronavirus infection, during funeral rites at Belgrade's St. Sava temple, in Belgrade, Serbia, November 21, 2020. REUTERS/Marko Djurica

A mourner pays her respect over the casket of Serbia's late Patriarch Irinej, who died of coronavirus infection, during funeral rites at Belgrade's St. Sava temple, in Belgrade, Serbia, November 21, 2020. REUTERS/Marko Djurica