IVAC Director Duong Huu Thai was quoted as saying that the second phase involves 375 volunteers who will be divided into two age groups, one aged above 18 and the other aged over 60.

The volunteers will receive shots of varying doses: 3mcg and 6 mcg. 

Covivac underwent pre-clinical trials in India, the U.S., and Viet Nam, the IVAC Director said, adding that the results from those trials showed that the vaccine has satisfied all conditions for testing on humans.

In the first stage of human trials, 120 volunteers aged between 18 and 59 participated in the trials of Covivac made by the IVAC based in Nha Trang city, Khanh Hoa province. They were divided into five groups - 20 who receive the placebo, and 100 who are injected with the vaccine at three different levels of 1, 3 and 10 micrograms.

An interim report which was sent to the National Council of Ethics in Biomedical Research assessed that the vaccine is safe, well tolerated, and immunogenic across all age groups. 

Previously, Viet Nam's first candidate, Nanocovax, started Phase 2 trials on February 26, with 560 volunteers divided into four groups for the placebo injection and doses of 25, 50 and 75 micrograms.

Last Saturday, the ministry's Ethical Evaluation Committee in Biomedical Research said that Nanocovax was "safe and able to elicit an immune response" but it had not assessed the vaccine's protection efficacy. 

Authorities are expected to grant emergency approval for Nanocovax as long as all the study results are approved by the ethical committee. If everything goes as planned, Viet Nam will have its first domestic COVID-19 vaccine in the fourth quarter of the year.

The phase 3 human trials of Nanocovax is currently being carried out on 13,000 people in Ha Noi, northern Hung Yen province and the Mekong Delta provinces of Tien Giang and Long An.