The second phase of testing will be carried out early June, said Dr. Do Tuan Dat, head of the Hanoi-based VABIOTECH company, which produces vaccines.

During the first testing phase, 50 mice in the lab remained healthy two weeks after they were injected with the vaccine on April 26.

On May 14, researchers sent the mice’s blood samples to the National Institute of Hygiene and Epidemiology for first evaluation.

The vaccine has been developed by collaborating scientists of VABIOTECH and the U.K.’s Bristol University.

Dat said that since the end of January when the Covid-19 pandemic broke out in Vietnam, VABIOTECH researchers have been working with scientists at the Bristol University to produce a vaccine for the disease.

If the tests prove successful on mice, the research team will seek funding from international agencies to take their work further.

The company estimates it will take at least 12-18 months to develop a Covid-19 vaccine that can work safely on humans.

A vaccine is generally considered the most effective way to fight a viral disease.

There is currently no approved vaccine or medication for the Covid-19, which has infected more than five million people with reported deaths rising above 329,000.

Around 150 Covid-19 vaccine development projects are being carried out worldwide. Eight vaccines have begun human testing. On Monday, Moderna, the Massachusetts biotechnology company, announced promising early results from its first human safety tests on eight volunteers.

With no new case confirmed, Wednesday marked day 34 without a new coronavirus infection caused by community transmission in Vietnam.

The nation's Covid-19 tally now stands at 324, with 60 active cases, the rest having recovered.