Dozens of candidates are being developed in nations from the US to China, with at least three in human testing, according to the World Health Organization. They are from CanSino Biologics and the Beijing Institute of Biotechnology; Inovio Pharmaceuticals; and Moderna along with the National Institute of Allergy and Infectious Diseases. Human trials of a potential vaccine being developed by Oxford University researchers are set to begin on Thursday, the UK government said.