Phase one of a clinical trial for the world's first inactivated vaccine against COVID-19 will take place in the city of Jiaozuo, Henan province, the northern neighbor of hard-hit Hubei province, the vaccine maker said on April 14.

The vaccine was approved for clinical trial by the National Medical Products Administration on Sunday. It is made by the Wuhan Institute of Biological Products Co－a subsidiary of the China National Biotech Group Company－and the Wuhan Institute of Virology of the Chinese Academy of Sciences. The trial's start date is unknown.

According to the Chinese Clinical Trial Registry, a database of clinical trials in China, the vaccine has passed ethical review and is currently at the "prospective registration" phase for both phase one and phase two clinical trials, which will be randomized, double-blind, placebo controlled experiments.

The trials aim to "evaluate the safety and immunogenicity of inactivated novel coronavirus pneumonia vaccine in healthy people aged 6 years and above", the registry said. The study is estimated to conclude before Nov 10, 2021.

Phase one will feature 288 volunteers, 216 of whom will receive different doses of the vaccine while the remaining 72 take placebos. Phase two will enroll 1,168 volunteers, with 876 participants taking the vaccine and 292 in the control group.

Xia Shengli, the head of the trials, told local media that conducting the tests in Henan province rather than in its hard-hit neighbor can remove distractions, making it easier to verify the vaccine's safety and effectiveness.

The vaccine maker said it has the infrastructure to mass produce over 50,000 inactivated vaccines in a single batch and make more than 100 million vaccines annually.

An inactivated vaccine uses the killed version of the germ that causes a disease to trigger an immune response, and thus is incredibly safe because dead germs can't cause illness, according to the United States Department of Health and Human Services.

It is used to safeguard against hepatitis A, influenza, rabies and polio. However, inactivated vaccines don't provide strong immunity, and people may need several booster shots over time to get ongoing protection.

On Jan 19, the China National Biotech Group Company said it had invested 1 billion yuan ($141 million) into a special vaccine development program, spearheaded by noted vaccine expert Yang Xiaomin, that led to the creation of the inactivated vaccine. Another type of vaccine based on genetic engineering is also in the pipeline.

The World Health Organization said on Saturday that there are now 70 candidate vaccines in development. Experts around the world estimate it would take around 12 to 18 months to get a vaccine approved for mass use.

Wu Zunyou, chief expert in epidemiology at the Chinese Center for Disease Control and Prevention, said in a news briefing that, theoretically, the quickest Chinese vaccine would still need at least six months to go through the three phases of clinical trials.

The first phase primarily tests for safety and will last at least 20 days, he said. For phase two, which focuses on efficacy and side effects, the recruitment process alone will take at least a month. The third phase, which involves the most volunteers and includes broader tests for efficacy, will need from three to five months to be completed.

Wang Junzhi, a senior biopharmaceutical expert, said on Tuesday that phase three trials are the most important and time consuming because they need thousands－in some cases, even tens of thousands－of volunteers to provide enough scientific evidence to support a vaccine going to market.

"Even during an emergency, we cannot lower the standards of safety and efficacy when reviewing a vaccine," he said."The public is paying a lot of attention. We hope to make some important progress in vaccine development so that safe and effective vaccines can hit the market soon."