They are part of the 80 million doses that U.S. President Joe Biden has pledged to donate to various countries.

Around 41 million will be shared through Covax, with Vietnam being among the Asian beneficiaries, and the rest are meant for "regional priorities and other recipients," also including Vietnam.

Speaking at a ceremony marking the arrival, Charge d’Affaires, a.i., Christopher Klein, said: "The shipment gives us hope that there is an end in sight to our fight against Covid-19. It gives us hope that we will be able to return to our normal lives," according to a statement from the U.S. Embassy in Hanoi.

The government last month approved the emergency use of the Moderna vaccine, the fifth after Russia's Sputnik V and those made by the U.S.'s Pfizer and Germany's BioNTech, China's Sinopharm and British-Swedish firm AstraZeneca.

Moderna is developed from messenger RNA, or mRNA, which contains instructions for human cells to construct a harmless piece of the coronavirus called the spike protein that triggers an immune response in humans.

Some 53 countries and territories have been using it including the U.S., Canada, the European Union, the U.K., Israel, and Singapore.

According to the Ministry of Health, about 105 million doses from various sources have been committed for use in Vietnam, where vaccination using the AstraZeneca vaccine began in March.

Around four million of the country’s 96 million people have got shots, with 258,274 of them getting both doses.