BEIJING (Reuters) – A potential COVID-19 vaccine being developed by Chinese researchers showed promise in trials in monkeys, triggering antibodies and raising no safety issues, researchers said, and a human trial with more than 1,000 participants is under way.

The vaccine candidate, called BBIBP-CorV, induced high-level neutralising antibodies that can block the virus from infecting cells in monkeys, rats, guinea pigs and rabbits, researchers said in a paper published in online by the medical journal Cell on Saturday.

“These results support the further evaluation of BBIBP-CorV in a clinical trial,” researchers said in the paper. 

BBIBP-CorV, developed by Beijing Institute of Biological Products affiliated to state-owned China National Pharmaceutical Group (Sinopharm), is among five candidates China is testing in humans.

More than 100 potential COVID-19 vaccines are in various stages of development around the world. Among front runners currently in human trials are being developed by AstraZeneca (AZN.L), Pfizer (PFE.N), BioNtech (22UAy.F), Johnson & Johnson (JNJ.N), Merck (MRK.N), Moderna (MRNA.O), Sanofi (SASY.PA) and China’s CanSino Biologics.

As well as appearing safe and able to generate an immune response in animals, BBIBP-CorV did not appear to trigger antibodies that could boost the infection – a phenomenon known as antibody-dependent enhancement (ADE)- the researchers said, although this does not necessarily guarantee ADE won’t occur in human tests.

Apart from BBIBP-CorV, Sinopharm, which has invested 1 billion yuan ($141.40 million) in vaccine projects, is testing in humans another vaccine candidate developed by its Wuhan-based unit. The two shots have been given to more than 2,000 people in clinical trials.