Severe acute respiratory syndrome (SARS)

Summary

SARS summary1-3

Pathogenic agent

Severe acute respiratory syndrome coronavirus (SARS-CoV)

Location

China, Hong Kong SAR, Taiwan, Singapore, Canada, limited cases in other countries in Asia, Europe, USA

Transmission

Airborne route in droplets of saliva; hand contact with contaminated surfaces; trajectory of 2003 epidemic linked with air travel routes; distinct possibility of further outbreaks

Epidemiology

  • The 2003 SARS outbreak caused over 8000 infections and 800 deaths
  • Case-fatality rate (CFR) estimated up to 9.6%
  • Most patients were previously healthy adults aged 25–70 years

Before this century, coronaviruses were a relatively obscure family of viruses known to cause the common cold in humans.1 In 2002, a new coronavirus emerged, causing an epidemic outbreak of pneumonia, first reported in China, followed by other Asian countries, with several cases also appearing in Canada and the US.1 The outbreak was controlled by the strict isolation of patients, and the following year the virus was identified and characterized as Severe Acute Respiratory Syndrome coronavirus (SARS-CoV).1

The 2002–2003 SARS outbreak went on to cause over 8000 infections and almost 800 deaths1—a high case-fatality ratio of 9.6%.1 Most patients were previously healthy adults aged 25–70 years3 and 21% of cases were healthcare workers.4

What characterizes SARS?

SARS presents as a fever, shortness of breath, and lower respiratory tract infection, with some people also experiencing gastrointestinal complications.1 When studied using an electron microscope, coronaviruses appear as spherical particles covered in spikes—they look like the sun’s corona (atmosphere) or crown, hence the name “coronavirus.”1 Coronaviruses can infect many animal species.1,5 While in the original animal host, they undergo mutations and develop into new strains, which can spread to humans by touching a surface or object contaminated with infectious droplets and then touching one’s mouth, nose, or eyes or through droplets in the air—a process known as zoonotic transfer.1,6 These constantly evolving strains have the potential to cause severe respiratory diseases.6 Live animals handled by Chinese market traders were likely the zoonotic origin of SARS-CoV.1

Need for vaccine development

SARS-CoV has the potential to spread rapidly, cause death and disability, and disrupt economies, and so remains a serious public health concern.6 Currently, there is no antiviral therapy for SARS.1 While it is not clear whether SARS-CoV will again emerge into the human population, it is certain that the evolution and spread of new disease-causing coronaviruses, such as MERS (2012) and COVID-19 (2019), pose an ongoing threat to human health and survival. Because future global outbreaks remain an ominous scenario, effective vaccines against SARS-CoV and other coronaviruses will be an invaluable component of our defense against them.

  1. Weiss SR, Navas-Martin S. Coronavirus pathogenesis and the emerging pathogen severe acute respiratory syndrome coronavirus. Microbiol Mol Biol Rev. 2005;69:635–664.
  2. World Health Organization. Summary of probable SARS cases with onset of illness from 1 November 2002–31 July 2003. 24 July 2015. Available at: https://www.who.int/publications/m/item/summary-of-probable-sars-cases-with-onset-of-illness-from-1-november-2002-to-31-july-2003 [Accessed 27 Aug 2021].
  3. World Health Organization. Severe Acute Respiratory Syndrome (SARS). Available at: https://www.who.int/health-topics/severe-acute-respiratory-syndrome#tab=tab_1 [Accessed 27 Aug 2021].
  4. Cherry JD. The chronology of the 2002–2003 SARS mini pandemic. Paediatr Respir Rev. 2004;5(4):262–269.
  5. Chang L, et al. Coronavirus disease 2019: coronaviruses and blood safety. Transfus Med Rev. 2020;34:75–80.
  6. de Wilde AH, et al. Host factors in coronavirus replication. Curr Top Microbiol Immunol. 2018;419:1–42.