A new, and often deadly, virus which is sweeping the globe has infected thousands, with no apparent regard for race, gender or nationality. But one group has so far come through virtually untouched -- children.

Doctors are trying to explain why a virus that moves with relative ease through the adult population, so far infecting 3,000 worldwide with more than 100 dead, has come up against something of an immunological wall when it comes to youngsters.

In the south China city of Guangzhou, just miles from where the outbreak began, Guangzhou Children's Hospital has yet to see its first patient with Severe Acute Respiratory Syndrome, officials said this week.

"We haven't had any cases of SARS," said Yu Minghua, chief of paediatrics at south China's largest hospital for children. "No one has died and no one has been on a respirator...this hospital has about 300 doctors, and none of them has got SARS either."

China, especially southern Guangdong province where the disease emerged in November, has been criticised by the World Health Organisation for not fully reporting the real number of SARS cases early enough.

But the resistance of children to SARS is a phenomenon that is seen in other places too where the disease has struck hardest.

In Singapore, just three of the 126 cases to date, or 2.4 per cent, are children under the age of 18, according to government data published on Thursday.

Out of about 1,000 sufferers in Hong Kong, "the number of children infected with SARS is low...and they had close contacts with SARS patients before infection," Hong Kong's Department of Health told Reuters in a statement. It said more specific data was not available.

A Chinese official could not say how many of the 1,206 people who have come down with the disease in Guangdong were children.

But Yu said that no children with SARS had come through her hospital before being transferred to Guangzhou's No 8 People's Hospital where many of the city's SARS sufferers have been quarantined.

The latest research, published by two teams in the England Journal of Medicine on Thursday, identifies the virus as a completely new version of the coronavirus family, the infection that causes the common cold, among other diseases.