State-owned media in China reported Tuesday that researchers will soon begin testing a vaccine for Severe Acute Respiratory Syndrome (SARS) on human volunteers.
China's State Food and Drug Administration called the move "a milestone in the nation's anti-SARS efforts." However, the World Health Organization was cautious about the tests on Tuesday.
Peter Cordingley, a WHO spokesman, warned the trials should follow all international standards. "There are certain reservations, we are stressing elements like safety and vaccine development protocol," he said. "We wouldn't want any of these steps to be overlooked or jumped."
The disease first broke out in late 2002 in southern China and spread to about 8,000 people worldwide in eight months. More than 700 SARS patients died.
China has confirmed three cases of SARS this month. Health authorities around Asia fear a repeat of the first outbreak and are monitoring visitors for fever and respiratory illness.
Hong Kong health authorities said Tuesday a tourist from mainland China has tested negative for SARS after he was hospitalized with a respiratory infection, a symptom of the disease.
Asia also faces a threat from bird flu. So far, the disease has spread to poultry farms in Japan, Taiwan, South Korea and Vietnam. The WHO is sending more experts to Vietnam, where the bird flu has infected and killed at least five people.
Some experts believe the outbreaks could have been avoided if all poultry were vaccinated against the H5N1 virus that causes the flu.
Bird flu first jumped from chickens to infect humans in 1997 in Hong Kong. Six of the 18 people infected died.
Microbiologist Malik Peiris at Hong Kong University said the vaccine appears to have protected chickens in Hong Kong in recent months. "We suspect that if not for the fact that these chickens had been vaccinated, I think that Hong Kong also would probably be having some of the problems that are now being faced by Vietnam, South Korea and Japan," he said.
Dr. Peiris said a human vaccine against the chicken flu is being developed in the United States.
While the virus spreads rapidly through poultry flocks, human cases are still rare. Scientists believe the disease cannot be passed between people.