Skip to main content
hpa logo
Topics A-Z:
Search the site:
Home › Topics › Infectious Diseases › Infections A-Z › Severe Acute Respiratory Syndrome (SARS) ›General Information ›  Background information on SARS
Printer friendly page (opens in new window)

Background information on SARS

On 12 March 2003, the World Health Organization (WHO) issued a global health alert for authorities to be aware of a new atypical pneumonia called Severe Acute Respiratory Syndrome (SARS) reported in several countries in south-east Asia1. SARS probably had its origins in Guangdong Province, China. The earliest known cases were identified in mid-November 2002. Between March and July 2003, over 8,400 probable cases of SARS had been reported in 32 countries 2. The majority of cases occurred among close family members and hospital workers who have cared for SARS patients 3. During the global outbreak, the UK had four probable cases. Only one of these had a confirmed exposure to the SARS coronavirus. There was no spread of SARS from these cases and all four have fully recovered. On 5 July 2003 WHO issued a statement that the first global outbreak of SARS has been 'contained' 4. This was achieved using conventional public health measures of early detection of SARS cases, tracing the contacts of these cases, infection control in hospitals and dissemination of information to both health professionals and the public 5.

Between July 2003 and May 2004, four small and rapidly contained outbreaks of SARS have been reported; three of which appear to have been linked to laboratory releases of SARS-CoV 6. The source of the fourth outbreak remains unclear, although epidemiological investigations focused on an animal source.

  • The main symptoms of SARS are high fever (>38° C), cough, shortness of breath or difficulty in breathing. Symptoms should be severe enough to warrant hospitalisation and chest X-ray changes should show pneumonia or respiratory distress syndrome 7.
  • SARS appears to be less infectious than influenza. The incubation period is believed to be short, around two to seven days (maximum 10 days) 8, 9, 10.
  • Based on data from affected countries, the overall case fatality is 15%, though this is dependent on the age of the patient and co-morbidity (5). The case fatality is estimated to be less than 1% in persons aged 24 years or younger, 6% in persons aged 25 to 44 years, 15% in persons aged 45 to 64 years, and greater than 50% in persons aged 65 years and older 11.
  • The cause of SARS is now known to be a SARS coronavirus (SARS CoV), a new member of the coronavirus family. This family of viruses includes viruses, which cause the common cold. The SARS coronavirus has been isolated and further research is underway 12, 13, 14.
  • At present there are no early tests for SARS, and no vaccine or specific treatment, though scientists and clinicians around the world are working together on these issues 15.
  • More background information is available in the HPA questions and answers section and on the WHO website .
  • See interim guidance on case definition, reporting and management of SARS patients in the UK in the current/inter-epidemic period

(1) World Health Organization.WHO issues a global alert about cases of atypical pneumonia . Geneva: WHO, 2003. [online] [cited 28 August 2003].
(2) World Health Organization. Cumulative number of reported probable cases of Severe Acute Respiratory Syndrome (SARS). Geneva: WHO, 2003. [online] [cited 28 August 2003].
(3) World Health Organization.Update 58 - First global consultation on SARS epidemiology, travel recommendations for Hebei Province (China), situation in Singapore. Geneva: WHO, 2003. [online] [cited 28 August 2003].
(4) World Health Organization. SARS: breaking the chains of transmission. Geneva: WHO, 2003. [online] [cited 28 August 2003].
(5) World Health Organization.Update 83 - One hundred days into the outbreak. Geneva: WHO, 2003 . [online] [cited 28 August 2003].
( 6) World Health Organisation. Investigation into China's recent SARS outbreak yields important lessons for global public health. Western Pacific Region: WHO, 2004. [online] [cited 22 November 2004].
(7) World Health Organization. Alert, verification and public health management of SARS in the post-outbreak period. Geneva: WHO, 2003. [online] [cited 28 August 2003].
( 8) Booth CM, Matukas LM, Tomlinson GA, Rachlis AR, Rose DB, Dwosh HA et al. Clinical features and short-term outcomes of 144 patients with SARS in the greater Toronto area. JAMA 2003; 289: 2801-9.
( 9) Lee N, Hui D, Wu A, Chan P, Cameron P, Joynt GM et al. A major outbreak of severe acute respiratory syndrome in Hong Kong. N Engl J Med 2003; 348: 1986-94.
( 10) Wong GW,.Hui DS. Severe acute respiratory syndrome (SARS): epidemiology, diagnosis and management. Thorax 2003; 58: 558-60.
( 11) Donnelly CA, Ghani AC, Leung GM, Hedley AJ, Fraser C, Riley S et al. Epidemiological determinants of spread of causal agent of severe acute respiratory syndrome in Hong Kong. Lancet 2003; 361: 1761-6.
( 12) Peiris JS, Lai ST, Poon LL, Guan Y, Yam LY, Lim W et al. Coronavirus as a possible cause of severe acute respiratory syndrome. Lancet 2003; 361: 1319-25.
( 13) Drosten C, Gunther S, Preiser W, van der WS, Brodt HR, Becker S et al. Identification of a novel coronavirus in patients with severe acute respiratory syndrome. N Engl J Med 2003; 348: 1967-76.
( 14) Ksiazek TG, Erdman D, Goldsmith CS, Zaki SR, Peret T, Emery S et al. A novel coronavirus associated with severe acute respiratory syndrome. N Engl J Med 2003; 348: 1953-66.
( 15) Holmes KV. SARS coronavirus: a new challenge for prevention and therapy. J Clin Invest 2003; 111: 1605-9.


Last reviewed: 27 February 2009