The SARS epidemic was accelerated by the mobility of the human host and the fact that infected people were able to travel for a considerable length of time before being diagnosed. The best-described example is undoubtedly the story of the Chinese doctor who travelled from the Chinese province of Guangdong to Hong Kong on family business in February 2003.

On March 12, 2003, WHO published a global alert for the emerging SARS-Coronavirus on its website. Subsequently, for four months, the novel infectious disease gripped the world, and in particular Asia, and had a severe impact on public life and economy.

As it turned out, the doctor had been infected with the SARS virus while working in a hospital in Guangdong. During his stay in Hong Kong, the disease developed rapidly, and led to hospitalisation and ultimately to the death of the patient. His stay of one night (21 February 2003) at the Hotel M. (ironically in the subsequently re-numbered room 911) was sufficient to send the virus on air trips to Vietnam, Singapore and Canada (Toronto) via infected hotel guests. The virus started to spread rapidly in Guangdong as well as Hong Kong, especially among medical staff (for a detailed account, see the report of the Hong Kong SARS Expert Committee). It was Dr. Carlo Urbani, an Italian physician working for the World Health Organisation (WHO) in Vietnam, who realised that some of his patients suffered from an entirely new kind of infectious pneumonia. This resulted in a global alert by WHO, the first in the history of this organization, on March 16, 2003. In spite of the resulting measures, the epidemic developed further, especially in China, and the disease proved fatal to Dr. Urbani among others (Reilly et al., 2003).

In this period the impact of the epidemic on public life, politics and the economy of the stricken areas was enormous. An important stroke of luck in combating the disease was that it was transferred mainly through close contact, and in this sense was found to be much less contagious than influenza virus, for instance. On the other hand, there has been a lot of focus on the so-called "super spreaders" (Kwok et al., 2007), seriously ill patients who, for unexplained reasons, passed the virus on to a much larger than average number of other people. Thanks to extensive measures (protection and systematic quarantine) to avoid further spreading of the SARS virus, the world was declared officially SARS-free by WHO, rather sooner than expected, at the beginning of July 2003. From this time, with the exception of the above-mentioned four new cases in the winter of 2003-2004, only laboratory-related SARS cases were reported from Singapore, Taiwan, and China, with the latter outbreak (in the spring of 2004) resulting in the death of a close relative of one of the infected laboratory staff members.