A man receives shot of Sinovac COVID-19 vaccine during mass vaccination in Jakarta, Indonesia. Thursday, April 15, 2021. (AP Photo/ Achmad Ibrahim)

In this March 12, 2021 photo provided by Unity Health Care, Othon Sosua, right, talks with a patient during a vaccination drive in Washington, D.C. Homeless Americans who have been left off priority lists for coronavirus vaccinations — or even bumped aside as states shifted eligibility to older age groups — are finally getting their shots as vaccine supplies increase. Walk-up vaccine events are crucial for a population with limited access to cars, cellphones or Wi-Fi, organizers say. (Unity Health Care via AP)

World Health organization Director for Europe Hans Kluge speaks to media during a press conference where he said he would take an AstraZeneca vaccine when his turn comes for inoculation, at a vaccination center in Bucharest, Romania, Wednesday, April 7, 2021. British authorities recommended Wednesday that the AstraZeneca COVID-19 vaccine not be given to adults under 30 where possible because of strengthening evidence that the shot may be linked to rare blood clots, a recommendation that came as regulators both in the United Kingdom and the European Union emphasized that the benefits of receiving the vaccine continue to outweigh the risks for most people — even though the European Medicines Agency said it had found a "possible link" between the shot and the rare clots.(AP Photo/Andreea ALexandru)

People queue to receive a COVID-19 vaccine, outside the Stockholmsmassan exhibition center turned mass vaccination center, in Stockholm, Sweden, Thursday April 8, 2021. (Fredrik Sandberg/TT News Agency via AP)

Russian President Vladimir Putin speaks during a meeting via video conference at the Novo-Ogaryovo residence outside Moscow, Russia, Thursday, April 15, 2021. (Alexei Druzhinin, Sputnik, Kremlin Pool Photo via AP)

A man receives shot of Sinovac COVID-19 vaccine during mass vaccination in Jakarta, Indonesia. Thursday, April 15, 2021. (AP Photo/ Achmad Ibrahim)

In this image released by World Press Photo, Thursday April 15, 2021, by Henrik Hansson, titled Faces of Bridge, part of a series which won second prize in the Sports Stories category, shows An 11-year-old boy plays a 92-year-old man, at the Borlange Bridge Club, Borlange, Sweden, on 28 June 2020. (Henrik Hansson, World Press Photo via AP)

People queue to receive a dose of a COVID-19 vaccine, outside the Stockholmsmassan exhibition center turned mass vaccination center, in Stockholm, Sweden, Thursday April 8, 2021. (Fredrik Sandberg/TT News Agency via AP)

California Gov. Gavin Newsom, left, grabs a flyer as Tiburcio Vasquez Health Center CEO Andrea Schwab-Galindo, right, looks on during a visit with staff members at the health center's vaccination site at Our Lady of the Rosary church in Union City, Calif., on Thursday, April 15, 2021. The state expanded vaccine eligibility to all Californians aged 16 and older on Thursday. (Anda Chu/Bay Area News Group via AP)

FILE - In this April 10, 2021, file photo, registered nurse Ashleigh Velasco, right, administers the Johnson & Johnson COVID-19 vaccine to Olga Perez at a clinic held by Healthcare Network, in Immokalee, Fla. With coronavirus shots now in the arms of nearly half of American adults, the parts of the U.S. that are excelling and those that are struggling with vaccinations are starting to look like the nation’s political map: deeply divided between red and blue states. (AP Photo/Lynne Sladky, File)

FILE - In this April 12, 2021, file photo, Freeson Wong, 31, takes a selfie as he receives a dose of the Moderna vaccine at a vaccination center in the Chinatown neighborhood of Los Angeles. The United States opened more distance between itself and much of the rest of the world on Thursday, April 15, nearing the 200 millionth vaccine administered in a months-long race to protect the population against COVID-19, even as other countries, rich and poor, struggle with stubbornly high infection rates and deaths. (AP Photo/Jae C. Hong, File)

FILE— In this Feb. 9, 2021, file photo, Parsa Namaki, center, son of Health Minister Saeed Namaki, left, is injected with the Russian Sputnik V coronavirus vaccine in a staged event at Imam Khomeini hospital in Tehran, Iran, Iran. Iran has finalized a deal with Russia over purchasing 60 million doses Sputnik V Coronavirus vaccine, state-run IRNA news agency reported Thursday, April 15, 2021. (AP Photo/Vahid Salemi, File)

Secretary of State Antony Blinken announces his appointment of Gayle Smith as the new State Department Coordinator for Global COVID-19 Response and Health Security as he speaks about U.S. leadership in fighting the coronavirus pandemic at the State Department in Washington, Monday, April 5, 2021. (Al Drago/Pool via AP)

Kenyans line up to receive a dose of the AstraZeneca COVID-19 vaccine manufactured by the Serum Institute of India and provided through the global COVAX initiative, at Kenyatta National Hospital in Nairobi, Tuesday, April 6, 2021. (AP Photo/Brian Ingasnga)

Serbian President Aleksandar Vucic poses with a vial of the Sputnik V in Belgrade, Serbia, Thursday, April 15, 2021. Serbia has announced it will begin packing and later producing Russia's Sputnik V coronavirus vaccine, which would make it the first European state outside Russia and Belarus to begin manufacturing the jab. (AP Photo/Darko Vojinovic)

Messages written by loved ones and dedicated to the deceased hang from a wall at a memorial for COVID-19 victims installed outside the Basilica of Guadalupe in Mexico City, Wednesday, April 14, 2021. (AP Photo/Eduardo Verdugo)

The colors of the Brazilian Olympic team are projected on the statue of Christ the Redeemer by the Brazilian Olympic Committee as a reminder of how sport can inspire in the fight against COVID-19, one hundred days before the Tokyo Olympic Games, in Rio de Janeiro, Brazil, Wednesday, April 14, 2021. (AP Photo/Lucas Dumphreys)

Vials of the Sputnik V vaccine placed on a table prior to the visit of Serbian President Aleksandar Vucic in Belgrade, Serbia, Thursday, April 15, 2021. Serbia has announced it will begin packing and later producing Russia's Sputnik V coronavirus vaccine, which would make it the first European state outside Russia and Belarus to begin manufacturing the jab. (AP Photo/Darko Vojinovic)

In this photo provided by the Serbian Presidential Press Service, Serbian President Aleksandar Vucic receives a dose of the Chinese Sinopharm vaccine in the village of Rudna Glava, Serbia, Tuesday, April 6, 2021. Vucic finally rolled up his sleeve for a coronavirus vaccine Tuesday and to encourage his country's increasingly skeptical Serbs to get vaccinated themselves. (Serbian Presidential Press Service via AP)

Gayle Smith, the new State Department Coordinator for Global COVID-19 Response and Health Security, speaks about U.S. leadership in fighting the coronavirus pandemic at the State Department in Washington, Monday, April 5, 2021, as Secretary of State Antony Blinken listens. (Al Drago/Pool via AP)

People queue to receive a COVID-19 vaccine, outside the Stockholmsmassan exhibition center turned mass vaccination center, in Stockholm, Sweden, Thursday April 8, 2021. (Fredrik Sandberg/TT News Agency via AP)

FILE - In this March 11, 2021 file photo, directed by a nurse, a COVID-19 patient, back center, stretches her arms as part of a fitness program in a field hospital built inside the Citibanamex convention center in Mexico City. Mexico’s unwillingness to spend money, do more testing, change course or react to new scientific evidence contributed to the country being one of the worst hit by the coronavirus pandemic, according to a report released the third week of April, by the University of California, San Francisco. (AP Photo/Fernando Llano, File)

FILE - In this March 23, 2020 file photo, a victim of the COVID-19 virus is evacuated from the Mulhouse civil hospital, eastern France. The picture is still grim in parts of Europe and Asia as variants of the virus fuel an increase in new cases and the worldwide death toll closes in on 3 million. (AP Photo/Jean-Francois Badias, File)

FILE - In this Dec. 20, 2020, file photo, people stand in lines to get COVID-19 tests in Samut Sakhon, south of Bangkok. Thailand’s lucky streak faded late last year, when a virus cluster was found among migrant workers working in factories and seafood markets and living in crowded dormitories. Severe restrictions and a massive testing campaign near the outbreak's epicenter seemed to contain it after several weeks. (AP Photo/Jerry Harmer, File)