A staff member displays a sample of the COVID-19 inactivated vaccine at a vaccine production plant of China National Pharmaceutical Group (Sinopharm) in Beijing, capital of China, April 10, 2020. Photo:Xinhua

A Chinese-led research group recently announced in a study that their newly-developed inactivated vaccines for COVID-19 are effective and safe on macaques and other non-human primates such as rats. 

The study, published on Sunday in bioRxiv, an open access preprint repository for the biological sciences, also indicated that the inactivated vaccine, dubbed PiCoVacc, is able to trigger an effective humoral immune response in non-human primates, providing complete protection against the coronavirus strains with the proper dose. 

Through systematic analysis of clinical signs, hematology, and biochemical indicators in macaques, the researchers concluded that the vaccine was safe, and neither infection enhancement nor immunopathological exacerbation was observed in the studies.

The research team said although it's still too early to define the best animal model for studying COVID-19 infections, the experimental data supports the rapid clinical development of COVID-19 vaccines for humans.

Yang Zhanqiu, a virologist at Wuhan University, told the Global Times on Tuesday that macaques are more closely related to humans in terms of genes, so the results are convincing.

According to Yang, the inactivated vaccine has the advantages of advanced research and development technology, mature production process, controllable quality standard and good protective effects. It is the most effective path for developing vaccines for a novel disease, he added. 

According to the introduction from the World Health Organization, inactivated vaccines are made from viruses or other microorganisms that have been killed through physical or chemical processes, meaning the vaccine antigens cannot grow in the vaccinated person or cause diseases.

The research team is composed of scientists from laboratories and institutes affiliated with the Chinese Academy of Sciences and health authorities, including the Key Laboratory of Human Disease Comparative Medicine, Key Laboratory of Infection and Immunity, National Laboratory of Macromolecules, National Institute for Communicable Disease Control and Prevention under Chinese Center for Disease Control and Prevention.

On April 16, the first batch of 32 volunteers for the new inactivated vaccine had been inoculated, and the subjects responded well without showing obvious adverse reactions.