China's first recombinant protein subunit vaccine against COVID-19 was jointly developed by Anhui ZhifeiLongcom Biopharmaceutical and the Institute of Microbiology of the Chinese Academy of Sciences.

It is the first COVID-19 recombinant protein subunit vaccine to be approved for clinical use in the world. China approved the emergency use of the vaccine on March 10.

How the vaccine was developed

Amid the outbreak of COVID-19 epidemic, Anhui ZhifeiLongcom Biopharmaceutical, which has been engaged in vaccine R&D for more than 10 years, was the only company in Anhui province to develop a COVID-19 vaccine with the support of the local government and the CAS microbiology institute.

Researchers started Phase-1 and Phase-2 clinical trials for the vaccine in June and July last year, with no incidents of serious adverse reactions.

The Phase-3 trials have been launched in China, Uzbekistan, Pakistan, Ecuador and Indonesia. Uzbekistan approved the use of the vaccine on March 1.

How the vaccine differs from other COVID-19 vaccines

The difference between the subunit protein vaccine and others is that scientists create this version by growing a genetically modified version of the protein in cells before purifying it and turning it into a vaccine, said Yan Jinghua, a lead scientist behind the vaccine and a researcher from the CAS microbiology institute.

Yan said that one of the biggest advantages of the subunit vaccine is that it does not involve cultivating live viruses, meaning that the production process is safe and easy to scale up. In addition, this vaccine can be stored at temperatures between 2 C and 8 C, allowing for easy storage and transportation.

The recommended vaccination protocol for this vaccine involves three doses: no less than four weeks between two shots, the second dose should be administered within eight weeks after the first shot, and third dose administered within six months after the first.

Safety and efficacy

Trials have shown that the vaccine is safe and can elicit an antibody response, according to a study published in The Lancet Infectious Diseases journal.

The results of the Phase-1 and Phase-2 trials showed that 97 percent of participants who received three 25-microgram doses of the vaccine produced antibodies effective in neutralizing the virus, and their antibody levels were higher than that of recovered patients, an indication that the vaccine induces a stronger immune response, according to the study.