"We will continue to monitor post-injection reactions," said Dang Quang Ta, head of the General Department of Preventive Medicine under the Health Ministry.

The annoucement came amid rising global concerns over the safety of the vaccine, after European drug regulators on Wednesday confirmed a link between it and rare blood clots.

Yet the European Medicines Agency (EMA) said blood clots were very rare side effects of the AstraZeneca vaccine, and that countries should continue to use it anyway.

The World Health Organization echoed the opinion, adding the vaccine's benefits far outweigh its risks.

Vietnam's mass Covid-19 vaccination program was launched a month ago and the country has received 900,000 AstraZeneca vaccine doses from the producer and via the global Covax scheme.

As of Thursday, around 55,000 Vietnamese, mostly frontline workers in the Covid-19 fight, had received their first shots, and no cases of blood clotting have been recorded.

Reports about rare blood clots following inoculation with the Covid-19 vaccine produced by British-Swedish firm AstraZeneca had recently surfaced in certain countries, prompting some to suspend its use for people from 55 or 65 years old.

Vietnam aims to secure around 150 million doses this year to cover 70 percent of its 98 million population from the EU, U.S., Japan, China, India, and Russia.

AstraZeneca shots in Vietnam are delivered in two doses, four weeks apart.