A woman holds a small bottle labeled with a "Coronavirus COVID-19 Vaccine" sticker and a medical syringe in this illustration taken Oct 30, 2020. [Photo/Agencies]

Zheng Zhongwei, a senior expert on domestic vaccine research, said on Wednesday that five COVID-19 vaccines developed by China are undergoing phase-3 clinical trials.

Of the five vaccines, three are inactivated vaccines, which means they are made from chemically inactivated novel coronaviruses. That way, all the disease-causing proteins of the virus are preserved. This is a tried and tested method of making vaccines.

The fourth vaccine is made from adenoviruses, and uses another virus to trigger an immune response, and the fifth one from restructured protein viruses, by getting genes from the coronavirus and injecting them into neutral viruses and bacteria to produce vaccines. The adenovirus technology has been around for several years now and the fifth one for 30 years.

The most advanced technology is the one employed in messenger ribonucleic acid (mRNA) vaccine production, which would involve getting RNA from the novel coronavirus and injecting it into the human body as a vaccine.

The five Chinese vaccines can be preserved for 36 months at temperatures of 2 C to 8 C. An ordinary cold-chain transportation system can deliver them. That makes them of use in developing countries.

These vaccines have undergone ample tests, with about 60,000 volunteers in 125 countries having been inoculated. Not one of those who received the shot has reported serious side effects.

Also, more than 56,000 people traveled overseas after being vaccinated and still did not get infected.

The Chinese vaccines are not available in the market yet, but they will be of great help to the world when they are. As China has largely controlled the virus, it may not need many doses. The vaccine will be another of China's major contributions to the world.