BEIJING -- An inactivated COVID-19 vaccine candidate developed by the Institute of Medical Biology under the Chinese Academy of Medical Sciences has entered phase-2 clinical trials in China, the Science and Technology Daily reported on June 20.

The phase-2 trials, which further evaluate the immunogenicity and safety of the vaccine in humans, are conducted in the southwestern province of Yunnan.

The institute started the phase-1 clinical trials in May. Nearly 200 volunteers aged between 18 and 59 received the vaccine in West China Second University Hospital in Sichuan Province. The study was randomized, double-blind and placebo-controlled.

A COVID-19 vaccine manufacturing plant of the institute in Kunming, capital city Yunnan Province, will be put into use in the second half of 2020, according to the report.

The institute has rich experience and strong capabilities in vaccine research. It has developed and produced attenuated live vaccines and inactivated vaccines against polio, shielding hundreds of thousands of Chinese children from being disabled, the report said.

So far, five COVID-19 vaccine candidates have been approved for clinical trials in China, accounting for 40 percent of the total vaccines in clinical trials worldwide, according to the Ministry of Science and Technology.