What is Covid-19 – the illness that started in Wuhan? It is caused by a member of the coronavirus family that has never been encountered before. Like other coronaviruses, it has come from animals. What are the symptoms this coronavirus causes? The virus can cause pneumonia. Those who have fallen ill are reported to suffer coughs, fever and breathing difficulties. In severe cases there can be organ failure. As this is viral pneumonia, antibiotics are of no use. The antiviral drugs we have against flu will not work. Recovery depends on the strength of the immune system. Many of those who have died were already in poor health. Should I go to the doctor if I have a cough? In the UK, the medical advice is that if you have recently travelled from areas affected by coronavirus, you should: stay indoors and avoid contact with other people as you would with the flu call NHS 111 to inform them of your recent travel to the area More NHS advice on what to do if you think you have been exposed to the virus can be found here, and the full travel advice to UK nationals is available here. Is the virus being transmitted from one person to another? China’s national health commission confirmed human-to-human transmission in January, and there have been such transmissions elsewhere. How many people have been affected? As of 14 March, more than 148,000 people have been infected in more than 80 countries, according to the Johns Hopkins University Center for Systems Science and Engineering. There have over 5,500 deaths globally. Just over 3,000 of those deaths have occurred in mainland China. More than 71,000 people have recovered from the coronavirus. Why is this worse than normal influenza, and how worried are the experts? Sign up for Lab Notes - the Guardian"s weekly science update Read more We don’t yet know how dangerous the new coronavirus is, and we won’t know until more data comes in. Seasonal flu typically has a mortality rate below 1% and is thought to cause about 400,000 deaths each year globally. Sars had a death rate of more than 10%. Another key unknown is how contagious the coronavirus is. A crucial difference is that unlike flu, there is no vaccine for the new coronavirus, which means it is more difficult for vulnerable members of the population – elderly people or those with existing respiratory or immune problems – to protect themselves. Hand-washing and avoiding other people if you feel unwell are important. One sensible step is to get the flu vaccine, which will reduce the burden on health services if the outbreak turns into a wider epidemic. Have there been other coronaviruses? Severe acute respiratory syndrome (Sars) and Middle Eastern respiratory syndrome (Mers) are both caused by coronaviruses that came from animals. In 2002, Sars spread virtually unchecked to 37 countries, causing global panic, infecting more than 8,000 people and killing more than 750. Mers appears to be less easily passed from human to human, but has greater lethality, killing 35% of about 2,500 people who have been infected.