A staff member displays samples of the COVID-19 inactivated vaccine at Sinovac Biotech Ltd., in Beijing, capital of China, March 16, 2020. (Xinhua/Zhang Yuwei)

A Chinese-developed inactivated vaccine for COVID-19 has presented positive preliminary results in phase one and two clinical trials, becoming the first vaccine candidate in the world to show favorable immunogenicity and safety.

The Wuhan Institute of Biological Products, affiliated to China National Pharmaceutical Group (Sinopharm), announced on Tuesday that the company's COVID-19 inactivated vaccine candidate has not shown any cases of severe adverse effects in the first two phases of clinical trials.

The results show that the vaccine induced neutralizing antibodies for all 1,120 injected volunteers, aged from 18 to 59 years old. The neutralizing antibody seroconversion rate reached 100 percent, which shows the vaccine candidate can induce a positive immune response, according to a statement Sinopharm sent to the Global Times.

"It is the most comprehensive and effective clinical study of a COVID-19 vaccine so far, providing scientific data for epidemic prevention and control and emergency use in China, said the statement.

The clinical trials were designed as randomized, double-blind and placebo-controlled studies.

On April 12, the inactivated vaccine gained approval to enter the phase one and two clinical trials in Wuzhi county, Central China's Henan Province.

Meanwhile, Sinopharm has actively promoted phase three clinical trials for overseas cooperation and is currently contacting a number of vaccine producers and research teams regarding co-developing the vaccine.

Sinopharm has also established a high-level biosafety laboratory for the production of the COVID-19 vaccine to meet the needs of emergency use.