Severe acute respiratory syndrome (SARS)

SARS summary^1-3

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.

Weiss SR, Navas-Martin S. Coronavirus pathogenesis and the emerging pathogen severe acute respiratory syndrome coronavirus. Microbiol Mol Biol Rev. 2005;69:635–664.
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].
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].
Cherry JD. The chronology of the 2002–2003 SARS mini pandemic. Paediatr Respir Rev. 2004;5(4):262–269.
Chang L, et al. Coronavirus disease 2019: coronaviruses and blood safety. Transfus Med Rev. 2020;34:75–80.
de Wilde AH, et al. Host factors in coronavirus replication. Curr Top Microbiol Immunol. 2018;419:1–42.