A syringe with a dose of the vaccine against the coronavirus disease (COVID-19) is displayed at the Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital in Tokyo, Japan March 5, 2021. Yoshikazu Tsuno/Pool via REUTERS

Medical staffs prepare syringes with doses of the vaccine against the coronavirus disease (COVID-19) at the Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital in Tokyo, Japan March 5, 2021. Yoshikazu Tsuno/Pool via REUTERS

Medical workers rest after they received doses of the vaccine against the coronavirus disease (COVID-19) at the Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital in Tokyo, Japan March 5, 2021. Yoshikazu Tsuno/Pool via REUTERS

Syringes with doses of the coronavirus disease (COVID-19) vaccine are displayed at the Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital in Tokyo, Japan March 5, 2021. Yoshikazu Tsuno/Pool via REUTERS

A medical worker receives a dose of the vaccine against the coronavirus disease (COVID-19) at the Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital in Tokyo, Japan March 5, 2021. Yoshikazu Tsuno/Pool via REUTERS

A medical worker receives a dose of the vaccine against the coronavirus disease (COVID-19) at the Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital in Tokyo, Japan March 5, 2021. Yoshikazu Tsuno/Pool via REUTERS

A medical worker receives a dose of the vaccine against the coronavirus disease (COVID-19) at the Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital in Tokyo, Japan March 5, 2021. Yoshikazu Tsuno/Pool via REUTERS

A medical worker receives a dose of the vaccine against the coronavirus disease (COVID-19) at the Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital in Tokyo, Japan March 5, 2021. Yoshikazu Tsuno/Pool via REUTERS

A medical worker receives a dose of the vaccine against the coronavirus disease (COVID-19) at the Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital in Tokyo, Japan March 5, 2021. Yoshikazu Tsuno/Pool via REUTERS

Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital's president Terumi Kamisawa receives a dose of the vaccine against the coronavirus disease (COVID-19) in Tokyo, Japan March 5, 2021. Yoshikazu Tsuno/Pool via REUTERS

Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital's president Terumi Kamisawa receives a dose of the vaccine against the coronavirus disease (COVID-19) in Tokyo, Japan March 5, 2021. Yoshikazu Tsuno/Pool via REUTERS

Medical workers receive doses of the vaccine against the coronavirus disease (COVID-19) at the Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital in Tokyo, Japan March 5, 2021. Yoshikazu Tsuno/Pool via REUTERS

Healthcare workers of the Hospital de Clinicas hold placards and a mock coffin reading "Corruption kills", as they protest against the healthcare system collapse due to lack of medicines and vaccines, amid the coronavirus disease (COVID-19) outbreak, in San Lorenzo, Paraguay March 4, 2021. REUTERS/Cesar Olmedo

A medical staff member moves a patient at the Hospital de Clinicas in San Lorenzo, amid the coronavirus disease (COVID-19) outbreak, in Paraguay March 4, 2021. REUTERS/Cesar Olmedo

Relatives of patients suffering from the coronavirus disease (COVID-19) wait at the Hospital de Clinicas in San Lorenzo, as the outbreak continues, in Paraguay March 4, 2021. REUTERS/Cesar Olmedo

A healthcare worker of the Hospital de Clinicas holds a placard reading "Get out corrupt" as she protests the healthcare system collapse due to lack of medicines and vaccines, amid the coronavirus disease (COVID-19) outbreak, in San Lorenzo, Paraguay March 4, 2021. REUTERS/Cesar Olmedo

Health workers of the Hospital de Clinicas stand with a mock coffin reading "Corruption kills", as they protest the healthcare system collapse due to lack of medicines and vaccines, amid the coronavirus disease (COVID-19) outbreak, in San Lorenzo, Paraguay March 4, 2021. REUTERS/Cesar Olmedo

Healthcare workers of the Hospital de Clinicas carry a mock coffin reading "Corruption kills", as they protest the healthcare system collapse due to lack of medicines and vaccines, amid the coronavirus disease (COVID-19) outbreak, in San Lorenzo, Paraguay March 4, 2021. REUTERS/Cesar Olmedo

Healthcare workers of the Hospital de Clinicas carry a mock coffin reading "Corruption kills", as they protest the healthcare system collapse due to lack of medicines and vaccines, amid the coronavirus disease (COVID-19) outbreak, in San Lorenzo, Paraguay March 4, 2021. REUTERS/Cesar Olmedo

A bus moves outside St Bartholomew's Hospital, where Britain's Prince Philip has been admitted, in London, Britain March 4, 2021. REUTERS/Peter Cziborra

A view of St Bartholomew's Hospital, where Britain's Prince Philip has been admitted, in London, Britain March 4, 2021. REUTERS/Peter Cziborra

A woman smokes outside St Bartholomew's Hospital, where Britain's Prince Philip has been admitted, in London, Britain March 4, 2021. REUTERS/Peter Cziborra

People stand outside a hospital in Damascus, amid concerns over the spread of the coronavirus disease (COVID-19), in Damascus, Syria March 3, 2021. Picture taken March 3, 2021. REUTERS/Firas Makdesi

People stand outside a hospital in Damascus, amid concerns over the spread of the coronavirus disease (COVID-19), in Damascus, Syria March 3, 2021. Picture taken March 3, 2021. REUTERS/Firas Makdesi

Police officers stand outside St Bartholomew's Hospital, where Britain's Prince Philip has been admitted, in London, Britain March 4, 2021. REUTERS/Peter Cziborra

A police officer walks outside St Bartholomew's Hospital, where Britain's Prince Philip has been admitted, in London, Britain March 4, 2021. REUTERS/Peter Cziborra

An ambulance arrives at the St Bartholomew's Hospital, where Britain's Prince Philip has been admitted, in London, Britain March 4, 2021. REUTERS/Peter Cziborra

Police officers stand outside St Bartholomew's Hospital, where Britain's Prince Philip has been admitted, in London, Britain March 4, 2021. REUTERS/Peter Cziborra

Police officers stand outside St Bartholomew's Hospital, where Britain's Prince Philip has been admitted, in London, Britain March 4, 2021. REUTERS/Peter Cziborra

An ambulance leaves the St Bartholomew's Hospital, where Britain's Prince Philip has been admitted, in London, Britain March 4, 2021. REUTERS/Peter Cziborra

Police officers stand outside St Bartholomew's Hospital, where Britain's Prince Philip has been admitted, in London, Britain March 4, 2021. REUTERS/Peter Cziborra

A view of St Bartholomew's Hospital, where Britain's Prince Philip has been admitted, in London, Britain, March 4, 2021. REUTERS/Peter Cziborra

Cambodian Prime Minister Hun Sen arrives at Calmette hospital before receiving a dose of the AstraZeneca coronavirus disease (COVID-19) vaccine supplied by India, in Phnom Penh, Cambodia, March 4, 2021. REUTERS/Cindy Liu

Jeanine Mucci, RN, administers the Johnson & Johnson's coronavirus disease (COVID-19) vaccine to Susan Maxwell-Trumble, 67, at Northwell Health's South Shore University Hospital in Bay Shore, New York, U.S., March 3, 2021. REUTERS/Shannon Stapleton

Jeanine Mucci, RN, prepares to administer the Johnson & Johnson's coronavirus disease (COVID-19) vaccine to Susan Maxwell-Trumble, 67, at Northwell Health's South Shore University Hospital in Bay Shore, New York, U.S., March 3, 2021. REUTERS/Shannon Stapleton

Jeanine Mucci, RN, administers the Johnson & Johnson's coronavirus disease (COVID-19) vaccine to Susan Maxwell-Trumble, 67, at Northwell Health's South Shore University Hospital in Bay Shore, New York, U.S., March 3, 2021. REUTERS/Shannon Stapleton

Susan Maxwell-Trumble, 67, holds her vaccination card after receiving the Johnson & Johnson's coronavirus disease (COVID-19) vaccine at Northwell Health's South Shore University Hospital in Bay Shore, New York, U.S., March 3, 2021. REUTERS/Shannon Stapleton

Susan Maxwell-Trumble, 67, holds her vaccination card after receiving the Johnson & Johnson's coronavirus disease (COVID-19) vaccine at Northwell Health's South Shore University Hospital in Bay Shore, New York, U.S., March 3, 2021. REUTERS/Shannon Stapleton

A vial of the Johnson & Johnson's coronavirus disease (COVID-19) vaccine is seen at Northwell Health's South Shore University Hospital in Bay Shore, New York, U.S., March 3, 2021. REUTERS/Shannon Stapleton

Jeanine Mucci, RN, prepares to administer the Johnson & Johnson's coronavirus disease (COVID-19) vaccine to Susan Maxwell-Trumble, 67, at Northwell Health's South Shore University Hospital in Bay Shore, New York, U.S., March 3, 2021. REUTERS/Shannon Stapleton

Jeanine Mucci, RN, administers the Johnson & Johnson's coronavirus disease (COVID-19) vaccine to Susan Maxwell-Trumble, 67, at Northwell Health's South Shore University Hospital in Bay Shore, New York, U.S., March 3, 2021. REUTERS/Shannon Stapleton

Doctors Ines Veselinovic and Suzana Stojanovic stand at the intensive care unit of the Clinical Hospital Center, where they treat patients suffering from the coronavirus disease (COVID-19), in Nis, Serbia, March 3, 2021. REUTERS/Marko Djurica

Doctors Ines Veselinovic and Suzana Stojanovic stand at the intensive care unit of the Clinical Hospital Center, where they treat patients suffering from the coronavirus disease (COVID-19), in Nis, Serbia, March 3, 2021. REUTERS/Marko Djurica

A medical worker looks a a tablet at the intensive care unit of the Clinical Hospital Center, where she treats patients suffering from the coronavirus disease (COVID-19), in Nis, Serbia, March 3, 2021. REUTERS/Marko Djurica

Medical workers place a placard reading "The clinic of smiling people" at the intensive care unit of the Clinical Hospital Center, where they treat patients suffering from the coronavirus disease (COVID-19), in Nis, Serbia, March 3, 2021. REUTERS/Marko Djurica

Patients suffering from the coronavirus disease (COVID-19) are seen at the intensive care unit of the Clinical Hospital Center in Nis, Serbia, March 3, 2021. REUTERS/Marko Djurica

Medical workers treat a patient suffering from the coronavirus disease (COVID-19) at the intensive care unit of the Clinical Hospital Center in Nis, Serbia, March 3, 2021. REUTERS/Marko Djurica

Medical workers treat patients suffering from the coronavirus disease (COVID-19) at the intensive care unit of the Clinical Hospital Center in Nis, Serbia, March 3, 2021. REUTERS/Marko Djurica

A medical worker treats a patient suffering from the coronavirus disease (COVID-19) at the intensive care unit of the Clinical Hospital Center in Nis, Serbia, March 3, 2021. REUTERS/Marko Djurica

A patient suffering from the coronavirus disease (COVID-19) is seen at the intensive care unit of the Clinical Hospital Center in Nis, Serbia, March 3, 2021. REUTERS/Marko Djurica

A medical worker treats a patient suffering from the coronavirus disease (COVID-19) at the intensive care unit of the Clinical Hospital Center in Nis, Serbia, March 3, 2021. REUTERS/Marko Djurica

Medical workers treat patients suffering from the coronavirus disease (COVID-19) at the intensive care unit of the Clinical Hospital Center in Nis, Serbia, March 3, 2021. REUTERS/Marko Djurica

A medical worker treats a patient suffering from the coronavirus disease (COVID-19) at the intensive care unit of the Clinical Hospital Center in Nis, Serbia, March 3, 2021. REUTERS/Marko Djurica

Medical workers stand at the intensive care unit of the Clinical Hospital Center, where they treat patients suffering from the coronavirus disease (COVID-19), in Nis, Serbia, March 3, 2021. REUTERS/Marko Djurica

Medical workers stand at the intensive care unit of the Clinical Hospital Center, where they treat patients suffering from the coronavirus disease (COVID-19), in Nis, Serbia, March 3, 2021. REUTERS/Marko Djurica

An ambulance drives outside St Bartholomew's Hospital, where Britain's Prince Philip has been admitted, in London, Britain, March 3, 2021. REUTERS/Henry Nicholls

A vial of the Johnson & Johnson's coronavirus disease (COVID-19) vaccine is seen next to hand sanitizer at Northwell Health's South Shore University Hospital in Bay Shore, New York, U.S., March 3, 2021. REUTERS/Shannon Stapleton

Johnson & Johnson's coronavirus disease (COVID-19) vaccines are seen at Northwell Health's South Shore University Hospital in Bay Shore, New York, U.S., March 3, 2021. REUTERS/Shannon Stapleton

Johnson & Johnson's coronavirus disease (COVID-19) vaccines are seen at Northwell Health's South Shore University Hospital in Bay Shore, New York, U.S., March 3, 2021. REUTERS/Shannon Stapleton