European Council President Charles Michel, second left, talks to Spanish Prime Minister Pedro Sanchez, right on a screen, during a video conference ahead of a EU summit at the European Council headquarters in Brussels, Wednesday, March 24, 2021. (Stephanie Lecocq, Photo Pool via AP)

FILE - In this Feb. 25, 2021, Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, listens as President Joe Biden speaks during an event to commemorate the 50 millionth COVID-19 shot in Washington. Fauci said Sunday, March 14, he wishes former President Donald Trump would use his popularity among Republicans to persuade his followers to get the COVID-19 vaccine. In a round of interviews on the morning news shows, Fauci lamented polling showing that Trump supporters are more likely to refuse to get vaccinated, saying politics needs to be separated from “commonsense, no-brainer” public health measures. (AP Photo/Evan Vucci, File)

Allison Oler, 17, receives her Pfizer vaccination, Wednesday, March 24, 2021, in Sandy, Utah. All adults in Utah aged 16 and older became eligible to receive COVID-19 vaccinations Wednesday. (AP Photo/Rick Bowmer)

Staff of Ochsner Health gather around a table to administer the Johnson & Johnson COVID-19 vaccine at the Castine Center in Pelican Park in Mandeville, La., on Wednesday, March 10, 2021. (Chris Granger /The Advocate via AP)

A health worker holds a dose of the AstraZeneca COVID-19 vaccine, during a mass vaccination campaign at San Pedro Hospital, in Logrono, northern Spain, Wednesday, March 24, 2021. Spain resumed the use of the AstraZeneca vaccine on Wednesday. (AP Photo/Alvaro Barrientos)

FILE - In this March 17, 2021, file photo, health worker administers a dose of a Pfizer COVID-19 vaccine during a vaccination clinic at the Grand Yesha Ballroom in Philadelphia. More than three months into the U.S. vaccination drive, many of the numbers paint an increasingly encouraging picture as dozens of states have thrown open vaccinations to all adults or are planning to do so in a matter of weeks. (AP Photo/Matt Rourke, File)

Belgium's Prime Minister Alexander De Croo speaks during a media conference after a meeting of the consultative committee of government ministers in Brussels, Wednesday, March 24, 2021. Ministers met on Wednesday to discuss a possible tightening of COVID-19 measures as infections are once again on the rise. (Benoit Doppagne, Pool via AP)

Health workers of the COVID-19 area embrace at the end of their shift at the Ana Francisca Perez de Leon II public Hospital in Caracas, Venezuela, Tuesday, March 23, 2021. (AP Photo/Matias Delacroix)

Soldiers stand guard during a vaccination campaign for the elderly in Iquitos, Peru, Thursday, March 18, 2021. Despite a scandal that shook the government in Peru's capital when over 480 government officials took advantage of their privileged positions to secretly receive early inoculations ahead of healthcare workers battling the new coronavirus pandemic, 66 people with connections in Iquitos jumped the queue this week to be vaccinated against COVID-19. (AP Photo/Rodrigo Abd)

In this photo provided by the Malacanang Presidential Photographers Division, Philippine President Rodrigo Duterte speaks to members of the Inter-Agency Task Force on the Emerging Infectious Diseases at the Malacanang presidential palace in Manila, Philippines on Wednesday March 24, 2021. The Philippine president has ordered at least nine city and town mayors investigated for possible charges after they reportedly jumped ahead of a priority list led by 1.7 million health workers and got injected with COVID-19 vaccine amid a shortage in supply. (King Rodriguez/ Malacanang Presidential Photographers Division via AP)

A demonstrator places a Brazil national flag on a mattress symbolizing COVID-19 victims, during a protest against the Government's handling of the COVID-19 pandemic, organized by the Rio de Paz NGO, in front of the Ronaldo Gazolla hospital in Rio de Janeiro, Brazil, Wednesday, March 24, 2021. (AP Photo/Silvia Izquierdo)

FILE - In this Saturday, March 20, 2021 file photo, few people walk on the streets after Poland reintroduced a partial nationwide lockdown on Saturday to curb a sudden spike in new COVID-19 cases, in Warsaw, Poland. Many regions in Central Europe and the Balkans are facing one of the most difficult moments since the coronavirus pandemic struck over a year ago. Poland recorded its highest daily number of new coronavirus infections Wednesday March 24, 2021, as hospitals buckled under a new surge. (AP Photo/Czarek Sokolowski, File)

Healthcare workers run testing on volunteers of the Soberana-02 COVID-19 vaccine as part of Phase III of one of two experimental Cuban vaccines in Havana, Cuba, Wednesday, March 24, 2021. (Ramon Espinosa/Pool Photo via AP)

A woman receives a dose of the AstraZeneca COVID-19 vaccine, during a mass vaccination campaign at San Pedro Hospital, in Logrono, northern Spain, Wednesday, March 24, 2021. Spain resumed the use of the AstraZeneca vaccine on Wednesday. (AP Photo/Alvaro Barrientos)

A woman walks with her shopping trolley after receiving a weekly pack of donated food and supplies in Barcelona, Spain, Wednesday, March 24, 2021. Food requests have increased considerably in the last months as Spain has been in lockdown due to the coronavirus pandemic. (AP Photo/Emilio Morenatti)

German Chancellor Angela Merkel, center, answers questions from lawmakers at German parliament Bundestag in Berlin, Germany, Wednesday, March 24, 2021. (AP Photo/Markus Schreiber)

James Veit, 33, rolls up his sleeve before receiving his Pfizer vaccination, Wednesday, March 24, 2021, in Sandy, Utah. All adults in Utah aged 16 and older became eligible to receive COVID-19 vaccinations Wednesday. (AP Photo/Rick Bowmer)

Eurogroup President Paschal Donohoe, top, European Central Bank President Christine Lagarde, bottom left, and European Commission President Ursula von der Leyen join an inter-institutional actors video conference meeting with European Council President Charles Michel at the European Council headquarters in Brussels, Thursday, March 11, 2021. (Aris Oikonomou, Pool Photo via AP)

A health worker holds up a vial of the AstraZeneca vaccine for COVID-19 at a vaccination center set up at the Allianz Stadium in Turin, northern Italy, Wednesday, March 24, 2021. Italian Government officials said on Wednesday doses of AstraZeneca vaccine at a packaging plant in central Italy were destined for Belgium, a statement that appeared to refute reports that the 29 million “hidden doses” were planned for export to Britain. (Fabio Ferrari/LaPresse via AP)

Children play in an inundated area of the Belen community in Iquitos, Peru, Saturday, March 20, 2021. Despite a scandal that shook the government in Peru's capital when over 480 government officials took advantage of their privileged positions to secretly receive early inoculations ahead of healthcare workers battling the new coronavirus pandemic, 66 people with connections in Iquitos jumped the queue this week to be vaccinated against COVID-19. (AP Photo/Rodrigo Abd)