Doctors in Hong Kong yesterday started prescribing heavier doses of medicine during the early stages of SARS after the surprise deaths of six relatively young patients with no other illnesses over the weekend.

　　However, one expert voiced fears that the virus believed to be causing severe acute respiratory illness has mutated.

　　Hong Kong yesterday reported seven new SARS deaths, for a total of 47. Many of the fatalities have been elderly people or patients suffering from other chronic health problems, such as heart or kidney disease.

　　But the six people whose deaths were reported over the weekend ranged in age from 35 to 52 and had no prior health problems.

　　Hospital Authority spokeswoman Elinda Luk said yesterday officials were investigating what had happened.

　　Hong Kong officials said previously that most patients with no aggravating health conditions seemed to respond well to a treat-ment of anti-viral drugs and steroids.

　　The acting director of the Hospital Authority, Dr Ko Wing-man, told lawmakers yesterday doctors were increasing the dosage and applying that treatment earlier to try to cure people before they have to receive intensive care.

　　But he warned of potentially severe side effects including heart, blood and kidney problems.

　　On a radio show yesterday, the senior executive manager of the Hospital Authority, Dr Liu Shao-haei, said some of the younger patients were hospitalized when they were already in serious condition, and their health worsened even after they received intensive care.

　　Ko told a radio talk show yesterday researchers are studying other treat-ments, including traditional Chinese medicines, but that they have been applied only on a small scale.

　　Despite efforts to find an effective treatment for the disease, an expert expressed concern that the virus has mutated after he observed that patients at the Prince of Wales Hospital, which was hard-hit by a SARS outbreak, displayed diffe-rences in infectiousness, symptoms and the severity of their illness.

　　Preliminary investigations revealed that the coronavirus believed to be causing SARS has "mutated, but not to a great extent," said biochemist Stephen Tsui of the Chinese University of Hong Kong yesterday.

　　"We want to find out whether it's because the virus is different that causes such differences," he said. "If we can figure that out, we can then predict which patient will be afflicted more severely."

　　Hong Kong reported 40 new SARS cases yesterday, for a total of 1,190, and although 229 people have recovered and been discharged, local officials have been unable to stop the spread of the disease. New cases have been cropping up daily.

　　Meanwhile, most universities and colleges in Hong Kong resumed classes yesterday with the adoption of a series of stringent measures to combat SARS.

　　Except Hong Kong Polytechnic University, which will resume classes on Monday, seven of Hong Kong's universities and colleges have resumed classes, according to a local radio report yesterday.

　　The report said the tertiary institutes have generally required their teachers and students to put on a protective masks and wash their hands frequently to prevent the spread of SARS.