The 811,200 doses have been transferred to the National Institute of Hygiene and Epidemiology (NIHE) for storage, awaiting the Health Ministry's instructions on distribution.

Vietnam had been promised 30 million doses of the AstraZeneca vaccine under Covax, a global mechanism for developing, manufacturing and procuring Covid-19 vaccine candidates that help member countries access vaccines as they become available.

The original plan was to deliver 1.37 million doses on March 25. But a lack of supply has meant that just 811,200 doses were made available in the first batch.

India, the world's biggest vaccine maker, has put a temporary hold on exports of AstraZeneca's vaccine being manufactured by the Serum Institute of India (SII), as the country focuses on meeting rising domestic demand.

The Serum Institute was due to deliver 90 million vaccine doses to Covax over March and April.

Rana Flowers, UNICEF's representative in Vietnam, said earlier that the production capability problems have led to delivery delays to all Covax-participating countries, not just Vietnam.

"However, Covax guarantees to give Vietnam over four million vaccine doses by the end of May despite the supply shortage. The remaining batches are scheduled to arrive in the country by the year-end or early 2022," she added.

Vietnamese officials have asked the private sector to step in after the Covax supplies were slashed. The country also wants to cooperate with India and Russia to develop Covid-19 vaccines and asked for China's help to inoculate prioritized groups, Health Minister Nguyen Thanh Long said Wednesday.

In February, Vietnam received about 117,000 AstraZeneca vaccine doses of the 30 million doses it has ordered from the producer, and started its mass vaccination campaign on March 8.

Over 50,000 Vietnamese, mainly frontline workers in the Covid-19 fight, have received their first Covid-19 vaccine shots.