They are the first among 120 volunteers in the trials to receive the second shot, which is administered 28 days after the first one.

Since the start of the trials, 96 volunteers have been injected with the first shot and the rest is expected to be inoculated by April 18.

In July, a mid-term report on the vaccine's trials is expected to be done.

Sixty six volunteers showed slight reactions like swelling in injected area and headache, which disappeared within 24 hours after injection without need for treatment, and no serious side effects were seen during the seven days after injection, according to Associate Professor, Dr. Pham Thi Van Anh, Head of the Ha Noi Medical University’s Centre of Clinical Pharmacology.

At present, Viet Nam has four vaccines under research and development by Nanogen Pharmaceutical Biotechnology JSC, the Institute of Vaccines and Medical Biologicals (IVAC), Vaccine and Biological Production Company No. 1 (Vabiotech) and the Center for Research and Production of Vaccines and Biologicals (Polyvac).

Nanocovax by Nanogen entered its second phase of human trials last month. The Covid-19 vaccine by Vabiotech is expected to begin human trials soon.

Viet Nam rolled out its mass COVID-19 vaccination campaign on March 8 by using British-Swedish firm AstraZeneca vaccine.

The country aims to obtain a total of 150 million vaccine doses this year to cover 70% its population./.