An inactivated vaccine candidate for the novel coronavirus developed by the Chinese Academy of Medical Sciences' Institute of Medical Biology entered phase two of clinical trials in China on Saturday, the Science Daily reported on Monday.

The second phase of clinical trials was launched in Honghe Hani and Yi autonomous prefecture in Southwest China's Yunnan province. The provincial disease control and prevention center is in charge of organizing the trials, and two city-level CDC centers in the prefecture's Mile and Gejiu have started screening for volunteers.

The institute is located in Kunming, capital of Yunnan.

During the second phase, researchers will further evaluate the experimental vaccine's efficacy in stimulating immune response in humans and its safety, and determine the proper procedures for giving shots and the dosage.

The institute gained approval from the National Medical Products Administration for rolling out the first and second phases of human trials for its experimental COVID-19 vaccine on May 13.

The first phase was recently completed in Sichuan University's West China Second University Hospital in Sichuan province, enrolling nearly 200 healthy volunteers aged 18 to 59.

In the meantime, the institute is ramping up production capacity in Kunming. A new plant equipped with biosecurity protections is expected to be put into use in the second half of the year.

"After months of effort, we have again bolstered the global fight against the disease as the pandemic remains severe and complicated," an unnamed staffer with the institute was quoted as saying.

The Ministry of Science and Technology said on Friday five domestically-developed COVID-19 vaccines — one vector and four inactivated — are going through clinical trials in China, accounting for about 40 percent of all vaccines entering human trials worldwide.