In late December, the Chinese authorities sent a public alert warning that “pneumonia of unknown cause” had been identified in Wuhan, in central China.
About ten days later, on January 7, scientists announced that a new coronavirus was causing the epidemic – quickly adding that it did not appear to have spread between humans.
At that time, less than 60 cases had been found. But now the disease, which has since been named Covid-19, has spread to more than 100 countries, infecting more than 467,000 people and killing more than 21,000 people.
In the UK, there have so far been 9,640 cases. A senior with underlying health conditions has become the first person in Britain to die after being diagnosed with the disease, confirmed the Royal Berkshire NHS Trust on March 5. A total of 465 people have since died.
This map, which updates automatically, shows where the disease is, how many cases there have been and how many people have died:
How has the disease spread around the world?
Chinese health officials were praised for their quick response to the disease and their transparency in sharing genetic data. The quarantine in Wuhan and other Chinese cities is said to have delayed the spread of the coronavirus to other countries by a few weeks.
However, experts said at the start of the epidemic that the disease did not spread easily from person to person. This has since been proven false, but may have contributed to the initial complacency.
Learn more: how many cases of coronavirus are in my area?
Because many infected people have no symptoms or only mild symptoms, the coronavirus may also have spread under the radar.
Some disease modellers believe that only 10% of cases in China and a third in the rest of the world are detected.
This map shows how the disease has spread around the world in a relatively short time:
How quickly has the disease spread?
At the start of the epidemic, the number of cases increased slowly – but then they started to snowball, with thousands of new cases reported every day.
In mid-February, the case definition changed to include clinically diagnosed cases, resulting in an increase of over 14,000 new cases overnight.
At the end of February, the number of new cases started to decrease in China but increased elsewhere.
This map shows how the number of cases has increased: