What is the virus causing illness in Wuhan?
It is a novel coronavirus – that is to say, a member of the coronavirus family that has never been encountered before. Like other coronaviruses, it has come from animals – possibly seafood. Many of those infected either worked or frequently shopped in the Huanan seafood wholesale market in the centre of the Chinese city. New and troubling viruses usually originate in animal hosts. Ebola and flu are examples.
What other coronaviruses have there been?
Severe acute respiratory syndrome (Sars) and Middle Eastern respiratory syndrome (Mers) are both caused by coronaviruses that came from animals. Although Mers is believed to be transmitted to humans from dromedaries, the original hosts for both coronaviruses were probably bats. The first cases of Sars were in China in late 2002. The authorities played them down and were subsequently much criticised because the virus 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.
What are the symptoms caused by the Wuhan coronavirus?
The virus causes pneumonia. Those who have fallen ill are reported to suffer coughs, fever and breathing difficulties. As this is viral pneumonia, antibiotics are of no use. Antiviral drugs may be used, but usually only lessen the severity of symptoms. If people are admitted to hospital, they may get breathing support as well as fluids. Recovery will depend on the strength of their immune system. Those who have died are known to have been already in poor health.
Is the virus being transmitted from one person to another?
Human to human transmission has been confirmed by China’s national health commission, although it does not appear to be happening easily as was the case with Sars. As of 23 January the Chinese authorities had acknowledged 517 cases and 17 deaths. In the past week, the number of confirmed infections has more than tripled and cases have been found in 13 provinces, as well as the municipalities Beijing, Shanghai, Chongqing and Tianjin. The virus has also been confirmed outside China, in the US, Thailand, South Korea, Taiwan and Japan. There have not been any confirmed cases in the UK at present, but there is definitely potential for cases to emerge due to the volume of international air travel. The actual number to have contracted the virus could be far higher as people with mild symptoms may not have been detected. Modelling by WHO experts at Imperial College London suggests there could be 4,000 cases, with uncertainty putting the margins between 1,000 and 9,700.
How worried are the experts?
There are fears that the coronavirus may spread more widely during the week-long lunar new year holidays, which start on 24 January, when millions of Chinese travel home to celebrate. At the moment, it appears that people in poor health are at greatest risk, as is always the case with flu. A key concern is the range of severity of symptoms – some people appear to suffer only mild illness while others are becoming severely ill. This makes it more difficult to establish the true numbers infected and the extent of transmission between people. But the authorities will be keen to stop the spread and will be anxious that the virus could become more potent than it so far appears.
Should we panic?
No. The spread of the virus outside China is worrying but not an unexpected development. It increases the likelihood that the World Health Organization will declare the outbreak to be a public health emergency of international concern on Thursday evening. The key concerns are how transmissible this new coronavirus is between people and what proportion become severely ill and end up in hospital. Often viruses that spread easily tend to have a milder impact.
Healthcare workers could be at risk if they unexpectedly came across someone with respiratory symptoms who had travelled to an affected region. Generally, the coronavirus appears to be hitting older people hardest, with few cases in children. Experts say there is no need for people to change their travel plans at this stage, but basic hygiene measures such as washing hands are sensible.