Overview of coronaviruses

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Last reviewed: 29 Apr 2025

Last updated: 17 Aug 2020

This page compiles our content related to coronaviruses. For further information on diagnosis and treatment, follow the links below to our full BMJ Best Practice topics on the relevant conditions and symptoms.

Coronaviruses are a large family of viruses, some of which cause illness in people, and others that circulate among mammals and birds. Rarely, animal coronaviruses can spread to humans, and then spread between people. Zoonotic coronaviruses have emerged in recent years to cause human outbreaks such as coronavirus disease 2019 (COVID-19), severe acute respiratory syndrome (SARS), and Middle East respiratory syndrome (MERS).

Illness in humans mainly manifests as a respiratory infection, or sometimes gastrointestinal infection. The clinical spectrum of illness varies from no symptoms or mild respiratory symptoms to severe, rapidly progressive pneumonia, acute respiratory distress syndrome, septic shock, or multiorgan failure resulting in death.

Condition	Description
Coronavirus disease 2019 (COVID-19)	go to our full topic on Coronavirus disease 2019 (COVID-19) An acute respiratory infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It was first identified in Wuhan City, Hubei Province, China, in December 2019. Since then it has spread to many countries around the world, with the World Health Organization declaring it a pandemic.
Middle East respiratory syndrome (MERS)	go to our full topic on Middle East respiratory syndrome (MERS) An acute viral respiratory tract infection caused by MERS-CoV. It was first identified in Saudi Arabia in 2012.[1] Cases have been limited to the Arabian Peninsula and its surrounding countries, and to travelers from the Middle East or their contacts. The case fatality rate is approximately 37%.
Severe acute respiratory syndrome (SARS)	go to our full topic on Severe acute respiratory syndrome (SARS) An acute viral respiratory tract infection caused by SARS-CoV. It was first identified in the Guangdong province of Southern China in 2002. The epidemic affected 26 countries and resulted in more than 8000 cases and 774 deaths in 2003. There have been no reported cases since 2004. The case fatality rate is approximately 10%.

Condition

Description

Coronavirus disease 2019 (COVID-19)

go to our full topic on Coronavirus disease 2019 (COVID-19)

An acute respiratory infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It was first identified in Wuhan City, Hubei Province, China, in December 2019. Since then it has spread to many countries around the world, with the World Health Organization declaring it a pandemic.

Middle East respiratory syndrome (MERS)

go to our full topic on Middle East respiratory syndrome (MERS)

An acute viral respiratory tract infection caused by MERS-CoV. It was first identified in Saudi Arabia in 2012.[1] Cases have been limited to the Arabian Peninsula and its surrounding countries, and to travelers from the Middle East or their contacts. The case fatality rate is approximately 37%.

Severe acute respiratory syndrome (SARS)

go to our full topic on Severe acute respiratory syndrome (SARS)

An acute viral respiratory tract infection caused by SARS-CoV. It was first identified in the Guangdong province of Southern China in 2002. The epidemic affected 26 countries and resulted in more than 8000 cases and 774 deaths in 2003. There have been no reported cases since 2004. The case fatality rate is approximately 10%.

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This overview has been compiled using the information in existing sub-topics.

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