Staff members transfer the first batch of China's Sinopharm COVID-19 vaccine purchased by Hungary at the Liszt Ferenc International Airport in Budapest, Hungary, Feb 16, 2021. (Photos: Xinhua)

A family doctor shows a box of China's Sinopharm COVID-19 vaccine in Varoslod, Hungary on Feb 24, 2021.

Serbian President Aleksandar Vucic (C) and China's ambassador to Serbia Chen Bo (L) welcome the shipment of China's Sinopharm inactivated coronavirus vaccines at the Belgrade Airport, Serbia, Jan 16, 2021.

Workers unload a container of China's Sinopharm vaccines at the Belgrade Airport, Serbia, Feb 10, 2021. [Photo/Xinhua]

A family doctor administers a dose of China's Sinopharm COVID-19 vaccine to a man in Nagykata, Hungary on Feb 24, 2021.

Serbian Health Minister Zlatibor Loncar receives a dose of Chinese COVID-19 vaccine in Belgrade, Serbia, on Jan 19, 2021.

European Council President Charles Michel (R) and European Commission President Ursula von der Leyen attend a press conference after the first day of a virtual summit in Brussels, Belgium, on Feb 25, 2021. Leaders of the European Union (EU) called for an accelerated production and delivery of COVID-19 vaccines late on Thursday as the bloc is struggling with supply shortfalls.