FILE - In this Feb. 17, 2021, file photo, a medical worker fills a syringe with a dose of the Pfizer-BioNTech COVID-19 vaccine at Tokyo Medical Center in Tokyo Wednesday, Feb. 17, 2021. Japan's rollout of COVID-19 vaccines began belatedly in mid-February, months behind the United States and many other countries. Officials blamed a shortage of Pfizer Inc. vaccine from Europe as the main culprit in the delay. But three months later, with shipments stabilized and officials attempting to accelerate vaccinations, Japan remains one of the world's least protected. (Behrouz Mehri/Pool Photo via AP, File)

Vials of the AstraZeneca COVID-19 vaccine sit in a table at the local vaccine center in Dunajska Streda, southern Slovakia, March 14, 2021. The AstraZeneca coronavirus vaccine should remain part of Slovakia’s vaccination program the country’s Health Minister said on Wednesday, May 12. Slovakia on Tuesday halted use of the two-shot AstraZeneca vaccine after Slovakia’s State Institute for Drug Control concluded last week that the death of a 47-year-old woman who received the AstraZeneca was “likely” linked to the vaccine. (Edmund Orzsik/TASR via AP)