Who is most at risk of contracting coronavirus?

There have been a number of deaths from the coronavirus among doctors who are young and, as far as we know, otherwise healthy.

Does this reframe who we thought was at risk?

According to Dr Bharat Pankhania, an expert on communicable disease control at the University of Exeter Medical School, it is not surprising that some young, healthy people die after contracting the virus, noting the risk of infection and even death is not zero for any demographic.

“All of us are at risk, and hence the superlative efforts at keeping containment in place, and keeping the virus from circulating as much as we can do,” he said.

David Heymann, professor of infectious disease epidemiology at the London School of Hygiene and Tropical Medicine, agreed. “This is a new disease in humans, so no-one has immunity– health workers, like everyone else, don’t have immunity,” he said.

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. Many of those initially infected either worked or frequently shopped in the Huanan seafood wholesale market in the centre of the Chinese city.

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.

What are the symptoms caused by the new coronavirus?

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?

UK Chief Medical Officers are advising anyone who has travelled to the UK from mainland China, Thailand, Japan, Republic of Korea, Hong Kong, Taiwan, Singapore, Malaysia or Macau in the last 14 days and who is experiencing a cough or fever or shortness of breath to stay indoors and call NHS 111, even if symptoms are mild.

Is the virus being transmitted from one person to another?

China’s national health commission has confirmed human-to-human transmission, and there have been such transmissions elsewhere.

How many people have been affected?

As of 20 Februrary, China has recorded 2,118 deaths from the Covid-19 outbreak. Health officials have confirmed 74,576 cases in mainland China in total. More than 12,000 have recovered.

The coronavirus has spread to at least 28 other countries. Japan has 607 cases, including 542 from a cruise ship docked in Yokohama, and has recorded one death. There have also been deaths in Hong Kong, Taiwan, France and the Philippines.

There have been nine recorded cases and no fatalities to date in the UK. As of 17 February, a total of 4,501 people have been tested in the UK, of which 4,492 were confirmed negative.

Why is this worse than normal influenza, and how worried are the experts?

We don’t yet know how dangerous the new coronavirus is, and we won’t know until more data comes in. The mortality rate is around 2% at the centre of the outbreak, Hubei province, and less than that elsewhere. For comparison, 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.

Is the outbreak a pandemic?

A pandemic, in WHO terms, is “the worldwide spread of a disease”. Coronavirus cases have been confirmed outside China, but by no means in all 195 countries on the WHO’s list. It is also not spreading within those countries at the moment, except in a very few cases. By far the majority of cases are travellers who picked up the virus in China.

Should we panic?

No. The spread of the virus outside China is worrying but not an unexpected development. The WHO has declared the outbreak to be a public health emergency of international concern. The key issues 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. Generally, the coronavirus appears to be hitting older people hardest, with few cases in children.

Sarah Boseley, Hannah Devlin and Martin Belam

Are some people more at risk?

Heymann said that who succumbs to the infection and who shrugs it off is often down to individual differences in the body’s response to the virus.

Some groups have a greater risk than others. “At the moment it appears that people who are at greater risk are the elderly and probably the very young,” said Pankhania.

But, he added, “you cannot have that only the elderly and the very young will die, it is part of the natural history of such infections that we will get deaths across the age ranges … The same pathophysiology can happen in the young as in the old.”

Are doctors more at risk of infection than non-medical staff?

In short, yes. “It is not surprising that fellow clinical colleagues have got infected and some have died,” said Pankhania, noting that medical professionals were in a special situation as they had multiple potential exposures to infection.

“You have got infection control in place, however if you are forever being targeted, on the one rare occasion where your guard slipped, you get infected,” he said. “It is like being in the battlefield – no matter how much protection you have, a stray bullet can catch you sometimes.”

Such a slip, he added, was not surprising. “A minor slip is eminently possible, especially when you are working under stress, you are tired, you have done long hours and your guard falls – and you get infected,” he said.

Repeated exposure puts you more at risk of contracting the virus, but does it make an infection worse?

Pankhania said that at present it was thought there was only one form of the virus in circulation, so doctors were not being exposed to a more serious strain.

But Heymann said that if doctors did become exposed to the virus, it might be in a higher dose than would have occurred in a social context – for example, they might come into contact with bodily fluids. “If there is a massive inoculum of virus, that could make it a more overwhelming infection,” he said.

Related: Could the coronavirus mutate if a vaccine can't be found in time?

Doctors are often exposed to all sorts of illness and disease from patients – could this make them more at risk of having a severe coronavirus infection?

That is a tricky question. Heymann said there was evidence that some patients in China infected with coronavirus also had flu at the same time. “If that were the case, this could possibly increase the severity of a coronavirus infection, just because the body is already fighting [flu], and it might overwhelm the system,” he said, but added that remained a theory.

However Heymann noted prior exposure to all sorts of bugs meant that health workers in general tended to have quite robust immune systems.

What precautions do doctors take when interacting with those infected with the coronavirus?

“In a clinical setting you need full personal protective equipment, so you would be fully gowned,” said Pankhania, adding that airtight masks were also used. “You can only breathe through the filter on that mask.”

Goggles were used, he added, noting it was possible to be infected through the eyes, while gloves were also important.

“A colleague has to watch you put [the equipment] on and a colleague has to watch you take it off, and you would systematically put it on and systematically take it off,” said Pankhania. “Otherwise you risk contaminating yourself in the process of taking it off.” But he added that under stress, mistakes could happen.

Can past epidemics provide clues to why some young, healthy people may die from the coronavirus infection?

Pankhania said the 1918 flu pandemic offered one possibility, noting that some young people showed an “exuberant immune response” – in other words, their immune system reacted too strongly to infection. “In some cases, as yet poorly explained, poorly understood, the immune response is over the top – that immune response then turns itself upon the person’s body itself,” he said, adding that could lead to fluid loss and organ damage. Buthe said it was not yet clear if this was at play in the current coronavirus outbreak.

Do any useful antiviral treatments exist?

The question remains open, but this week the World Health Organization director-general, Tedros Adhanom Ghebreyesus, told reporters that a number of trials were under way looking at the potential use of two HIV drugs as well as another antiviral called remdesivir that was developed to tackle haemorrhagic fevers including Ebola. Results, it seems, may be expected in three to four months. Meanwhile Columbia University researchers have received a $2m (£1.5m) grant to work on possible antivirals drugs and antibodies to tackle coronavirus.

What are the key things that remain unknown about the new coronavirus?

There are a lot of unknowns, including whether the virus could mutate to a more virulent form, while Pankhania said experts were still looking at the rate of deaths among those infected.

One key number is known as the R0, or basic reproduction number, which indicates how many new cases an infected person generates. At present it is thought to be about 2.6.

However, Pankhania said there was reason to be cautiously optimistic, noting that the figure might be lower outside of China, not least since other countries have had prior warning of the virus, while Wuhan is a densely populated city. He urged people in the UK to stay calm and said there was no reason to give up social events, quit the gym or keep children from playdates.

“That is absolutely overreacting,” he said. “At this point in time there is no coronavirus circulating in the UK in a free way.”

Some have compared the coronavirus situation to annual flu, noting the latter has killed more people. Does this mean we should not worry?

No, it is important to try to contain the coronavirus. “A new virus has emerged out of the blue,” said Pankhania, adding that it was believed to have started in bats, entered another animal and then passed to humans. “It can not only infect humans, but be transmitted among humans and cause disease,” he said. The upshot is the potential for a new virus circulating around the globe causing illness and death.

“It is an extra burden on humanity, and extra infection in addition to influenza, and there is also an unknownness about it, which is we don’t know how many people it could make very ill, we don’t know how many people it will take, hence our concerns,” he said.