Officials in Hong Kong launched a hunt for residents who fled a badly affected apartment complex, while President Bush issued an executive order allowing the forced quarantine of patients. Responding to criticism, China issued an apology for not warning people earlier about the dangers of the mysterious illness that began in the country.
President Bush's order allows the Health and Human Services secretary to decide when a quarantine is needed. It calls for the "apprehension, detention or conditional release of individuals to prevent the introduction, transmission or spread of suspected communicable diseases."
It names SARS, which has affected a suspected 115 people in the United States, as well as cholera, diphtheria, infectious tuberculosis, plague, smallpox, yellow fever and viral hemorrhagic fevers such as Ebola, Lassa and Marburg.
White House spokesman Scott McClellan said there were no plans to use the quarantine authority at this time. "This is just to make sure we are prepared for any eventuality," he said.
Secretary of Health and Human Services Tommy Thompson said Tuesday that such measures didn't yet appear warranted in the United States.
"If there is a virus that is explosive ... and the only way to control it is by quarantine, we have to consider it," he said. "But we're not there yet."
Legally, quarantine involves restricting the movement of healthy people who may have been exposed to an infectious disease and may be carrying it. Isolation, a related but less severe action, involves separating people who are already sick and often occurs within hospitals.
Another possible measure to prevent the disease's spread was endorsed Friday by the U.S. Surgeon General. Richard Carmona said he supports pre-screening passengers for the virus before they board airplanes for international flights.
The disease is thought to have originated in China's southern Guangdong province, and has since killed 84 people.
The Chinese government apologized Friday for its handling of the disease.
"Today, we apologize to everyone," said Li Liming, director of the Chinese Center for Disease Control.
"Our medical departments and our mass media suffered poor coordination," he said. "We weren't able to muster our forces in helping to provide everyone with scientific publicity and allowing the masses to get hold of this sort of knowledge."
China's government has been criticized for responding slowly in the SARS outbreak and for withholding information. Just this week, Beijing agreed to allow international health investigators to visit region where the disease first emerged.
Earlier this week, Thompson said the U.S. would pressure China for more information.
"It's important to see if we can work in more of a collaborative fashion with China," said Thompson. "I think we're going to put on more pressure."
On Friday, World Health Organization investigators reviewed some of the earliest known cases of SARS as they followed the fading tracks of initial transmission across southern China.
The WHO reported Friday that there were more than 1,200 cases of SARS in China. Hong Kong has the second highest number of infections; it reported 27 new cases of the disease on Friday, bringing its total to 761.
Meanwhile, Hong Kong police were looking for members of 113 families who had fled an apartment block in the crowded Kowloon district badly affected by SARS. Other residents of the complex have been quarantined.
"If our Health Department colleagues think these people may infect other people, we'll use minimal force to send them to hospital for treatment," a police spokesman said.