There were two chains of contagion in the outbreak that was first identified on April 22, said Liang. The first link in one chain was the first SARS patient identified, a woman surnamed Li. The first and only link in the second chain was a medical doctor surnamed Yang, who works at Chinese Center for Disease Prevention and Control's (CDC's) Institute of Virology in Beijing. Li passed the infection to five other people; Yang infected no one else.

Liang said that this year's SARS outbreak had clear chains of contagion, and although the virus was highly contagious it was spread mainly through close contact. The epidemic area was limited and diagnoses were clear.

Liang went on to say that after identifying the sources of contagion, Beijing promptly began epidemiological investigations, locating and placing under medical observation all the people who had had close contacts with the sources -- a total of 747 people. Strict sanitation and disinfection procedures were carried at all sites where suspected and confirmed cases had been, and in other quarantine areas.

At midnight on April 22, inspections began at all the Beijing laboratories working with the SARS virus: the Beijing Disease Prevention and Control Center, the Academy of Military Medical Sciences, Beijing Huada Gene Research Center, Peking University, Beijing Union Medical College Hospital and the CDC.

The Beijing Health Administration and related departments also inspected biosafety procedures at their labs in Beijing to make sure that the SARS virus and other hazardous samples are maintained only by designated organizations and in accordance with strict standards.

Liang said that Beijing was able to gain control over the outbreak quickly this year because of the importance with which the leadership views the matter, and because of their correct judgment, firm decisions and effective measures. This enabled Beijing to seize the initiative with prompt medical treatment, tracking and quarantine procedures.

(China.org.cn by Wang Qian, May 13, 2004)