Taiwan reacted with an outpouring of thanks to the United States for shipping 2.5 million COVID-19 vaccine doses to the island, more than doubling its arsenal as it deals with a rise in domestic infections.

Washington, competing with Beijing to deepen geopolitical clout through "vaccine diplomacy," initially had promised to donate 750,000 doses but increased that number as President Joe Biden's administration advances its pledge to send 80 million U.S.-made shots around the world.

"What a sight! What a gesture!" Taiwan Foreign Minister Joseph Wu tweeted in thanks late on Saturday, linking to pictures of the vaccines being loaded onto a China Airlines Boeing 777 freighter at Memphis airport.