A researcher says a SARS vaccine won't be available in the near future because of drug companies' reluctance to invest on developing it unless there is a SARS outbreak.

University of Hong Kong microbiologist Yuen Kwok-yung said on Thursday that 16 possible SARS vaccines are being developed worldwide, but only one has been picked up by a drug company in China, where it's in an early testing phase, China Radio International reported on Saturday.

Academic researchers won't progress from the animal testing phase unless drug companies invest money into testing the vaccines on humans.

SARS emerged in southern China's Guangdong province in late 2002. It killed 349 people on China's mainland and 774 worldwide, before subsiding in June 2003.