This page is updated regularly. Last reviewed 19th July 2021

What is COVID-19?

Coronavirus disease 2019 (COVID-19) is caused by a coronavirus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A coronavirus is a type of virus that causes respiratory tract infections, such as colds and pneumonia. Although coronaviruses usually cause mild symptoms, they can (on rare occasions) cause life-threatening breathing difficulties and death.

COVID-19

What we know so far

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Where did the disease originate?

Coronaviruses are common amongst animals. They’re ‘zoonotic’, meaning that they can be spread between humans and animals.

The reservoir - where microbes such as viruses live and grow - is under investigation. Early studies have suggested that the virus that causes COVID-19 is similar to bat coronaviruses. Research into where the infection started is ongoing, but a major source of the outbreak has been traced to a large seafood and animal market in Wuhan city, China (1,2,3).

The majority of people initially infected by the COVID-19 coronavirus had contact with the market in Wuhan city. Due to the ability of the virus to spread from person to person, it has since been declared a pandemic.

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How does COVID-19 spread?

According to the World Health Organization, it appears that the virus that causes COVID-19 spreads through respiratory droplets and aerosols. This means being in close contact with a confirmed case of COVID-19 with respiratory symptoms such as coughing and sneezing. Transmission may also be possible when an individual with COVID-19 speaks, sings or breathes heavily. The ease of transmission increases in crowded places, settings with close contact, and spaces with inadequate ventilation (4).

Transmission may also occur indirectly through contact with objects used by an infected person and similarly contaminated surfaces (4).

References

  1. World Health Organization, 2020. Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19). Available from: https://www.who.int/publications-detail/report-of-the-who-china-joint-mission-on-coronavirus-disease-2019-(covid-19).
  2. Andersen, K.G., Rambaut, A., Lipkin, W.I., Holmes, E.C. and Garry, R.F., 2020. The proximal origin of SARS-CoV-2. Nature Medicine, 26(4), pp.450-452.
  3. Mallapaty, S., 2020. Where did COVID come from? WHO investigation begins but faces challenges. Nature, 587, pp.341-342 .
  4. World Health Organization, 2020. Coronavirus disease (COVID-19): How is it transmitted? Available from: https://www.who.int/news-room/....

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