Thailand is conducting tests on macaque monkeys as it races to produce a cheaper, alternative coronavirus vaccine it hopes will be ready by 2021, a top researcher said Monday.

More than 100 candidate vaccines are currently in various stages of development around the world, at least eight of which are in clinical trials with humans, according to the World Health Organisation.

Oxford University researchers are considered the frontrunners in the race, starting clinical trials last month on a version based on a different virus that causes infections in chimpanzees.

At least two other companies -- pharmaceutical giant Pfizer and US-based Moderna -- are developing vaccines using the same technology, with the latter reporting positive preliminary results last week from clinical trials.

If the tests on the macaques go well, human trials should start in October, said Dr. Kiat Ruxrungtham, chair of the Chula Vaccine Research Center at Chulalongkorn University.