SARS, which plagued many parts of the world earlier this year, could reappear over the winter in single cases but it is unlikely there will be another outbreak in China, a prominent scientist said Sunday.

Epidemiologist Zhong Nanshan said he would not be surprised if two or three SARS cases were reported in the coming winter because as a virus-based disease it would hardly die out naturally. "But it is unlikely we'll see a large-scale spread of the disease, which we define as outbreak," Zhong said at a special session on SARS at the Meetings of the Third World Academy of Sciences (TWAS).

The SARS outbreak, which started in South China's Guangdong Province last November, infected 5,327 people in China and caused 349 deaths in the country.

As winter approaches, fears of a return of the highly infectious disease have been on the rise.

Public concern was further heightened by news reports in August that a young researcher was infected with SARS in a laboratory in Singapore.

Zhong, who was among the first researchers to identify the clinical existence of SARS, noted there is no need for panic as the Singapore case was isolated and might not have actually been the SARS virus.

He pointed out there have been no shades found in the X-ray of the lungs of the Singapore patient, an essential factor in diagnosing SARS cases. "He probably contracted another type of coronaviruses, of which the SARS virus is a type, but not the SARS virus," Zhong said.

But he insisted people still need to be highly vigilant as there are still many unknown factors related to SARS.

Although development of drugs or vaccines against the virus is under way in many labs worldwide and progress has been reported, Zhong said their availability in clinical terms may be "two or three years away at the earliest."

While concentrating on SARS prevention, there is a need to keep an eye on other diseases that may be as infectious and may combine with SARS to attack public health, Zhong noted.

He was echoed by Chen Zhu, another Chinese scientist who spoke at the session and described the SARS disease as "only a tip of the iceberg".

Zhong suggested it would be helpful to carry out vaccinations in large cities against influenza, a popular epidemic in winter, to prevent the outbreak of SARS. Influenza is also caused by a type of coronavirus and develops some symptoms similar to SARS cases, such as high fever.

"Such measures will make great sense because it will help doctors distinguish influenza patients from the suspected SARS patients,'' he said. "Otherwise it would be a disaster."

Precautionary measures have been carried out in China. The Ministry of Health has restarted its daily public information releases of the surveillance of SARS since late September, as it did during the epidemic period.

Up to now, no new suspected or confirmed cases have been reported to the ministry.