Intended for healthcare professionals


Severe acute respiratory syndrome: Imported cases of severe acute respiratory syndrome to Singapore had impact on national epidemic

BMJ 2003; 326 doi: (Published 19 June 2003) Cite this as: BMJ 2003;326:1393
  1. Annelies Wilder-Smith, head (epvws{at},
  2. Nicholas I Paton, head
  1. Travellers' Health and Vaccination Centre
  2. Department of Infectious Diseases, Tan Tock Seng Hospital, Jalan Tan Tock Seng, 308433 Singapore

    EDITOR—Travel is responsible for the rapid intercontinental spread of the severe acute respiratory syndrome (SARS).1 Singapore has one of the busiest airports in Asia, with numerous passengers arriving each day from countries affected by SARS, and it is therefore vulnerable to importation of the disease and potential transmission in the community.

    Six people are known to have imported SARS to Singapore between 25 February and 29 April 2003, all of whom had visited Hong Kong (plus Guangdong in two cases and Beijing in one case). Two cases were imported before this new disease was known, and the patients were admitted to a hospital a mean of four days after the onset of symptoms and placed in isolation six days later. One of these two initial cases resulted in extensive secondary transmission, leading to the current large national SARS epidemic.2

    With the rapid implementation of extensive public health education on SARS, enhanced infection control measures, and early isolation, the other four patients were admitted within a mean time of 2.5 days after the onset of symptoms and immediately isolated, and there were no secondary cases. The absence of transmission from these imported cases is probably because of their comparatively prompt identification and isolation, together with a low potential for transmission that characterises most cases of SARS (most transmission of SARS seems to be due to highly infectious individuals termed “super-spreaders” 3).

    Although importation of cases of SARS is likely to continue for the foreseeable future, our early experience in Singapore suggests that individuals importing SARS need not be a major hazard to the community if systems are in place to identify and isolate them efficiently.


    • Competing interests None declared.


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