About coronaviruses and COVID-19
COVID-19 is an infectious disease caused by a virus called SARS-CoV-2 that can be severe, particularly for people who are not up to date with vaccination - or have conditions that increase their risk of complications.
Some coronaviruses cause illness in humans, and others cause illness in animals. Rarely coronaviruses that usually only affect animals change to infect and spread among humans.
These new coronaviruses can cause severe disease in humans.
That is what happened with SARS-CoV-2. It started as a coronavirus that infected animals but changed to infect and spread among humans. This also happened with Severe Acute Respiratory Syndrome (SARS), which emerged in 2002, and Middle East Respiratory Syndrome (MERS), which emerged in 2012.
Read more about COVID-19 on the World Health Organisation website.