How does the coronavirus attack the human body?

The coronavirus could damage people's kidneys and send their immune systems 'haywire' as well as infecting the lungs, according to scientists.

More than 90,000 people have now been infected with the disease, which is known to cause serious lung damage and deadly pneumonia.

It does this by attaching to and reproducing in tissue inside the lungs, where it kills cells in the process of spreading.

As the cells are killed they drop off the lungs' linings and build up in clumps inside the organs, making it hard to breathe and triggering further infections.

The virus can also send the immune system into overdrive as it tries to fight off infection, triggering swelling which can lead to more breathing difficulties.

If a severe infection takes hold it may move on to cause damage or dysfunction to the stomach, intestines, heart, liver and kidneys, and even provoke organ failure. 

Around 90,000 people around the world have been infected with the coronavirus since the beginning of January, and more than 3,000 patients have died. 

Experts say the difficulty of containing the coronavirus is that so many patients have mild, cold-like symptoms and don't realise they have the infection – but it can quickly turn deadly

Experts say the difficulty of containing the coronavirus is that so many patients have mild, cold-like symptoms and don't realise they have the infection – but it can quickly turn deadly

The coronavirus outbreak, which is teetering on the edge of becoming a global pandemic, has so far infected almost 90,000 people worldwide and killed more than 3,000

The coronavirus outbreak, which is teetering on the edge of becoming a global pandemic, has so far infected almost 90,000 people worldwide and killed more than 3,000

The coronavirus is officially a respiratory infection, meaning it affects the lungs and airways. Typical symptoms are a cough, trouble breathing and a fever.

Among people who die from the infection – around 3.4 per cent of all patients, according to latest figures – most suffer from pneumonia, a lung infection which causes the airways to fill with fluid.

CORONAVIRUS COULD BE 1,000 TIMES MORE INFECTIOUS THAN SARS

The coronavirus could be up to 1,000 times more infectious than SARS because it plagues the body in the same way as HIV and Ebola, scientists warn.

Experts initially presumed the spread of COVID-19 would follow the same trajectory as the SARS outbreak in 2002/3, because the viruses are almost identical genetically. 

SARS, or severe acute respiratory syndrome, infected 8,000 people worldwide and killed 774 people in a year in 2002.

But in just two months the current coronavirus crisis has already hit around 90,000 and over 3,000 have succumbed to the illness. 

Nankai University researchers looked at the genome sequence of COVID-19 and found a section of mutated genes that did not exist in SARS.

Instead the coronavirus has 'cleavage sites' similar to those in HIV and Ebola, which carry viral proteins that are dormant and have to be 'cut' to be activated.

HIV and Ebola target an enzyme called furin, which is responsible for cutting and activating these proteins when they enter the body.

The viruses trick furin so it activates them and causes a 'direct fusion' between the virus and the human cells. COVID-19 binds to cells in a similar way, the scientists found.

'This finding suggests [the new coronavirus] may be significantly different from the SARS coronavirus in the infection pathway,' the scientists said in the paper.

'Compared to the SARS' way of entry, this binding method is "100 to 1,000 times" as efficient,' they wrote.

The study was published on Chinaxiv.org, an online platform used by the Chinese Academy of Sciences.

Professor Mark Fielder, a biologist at Kingston University in London, said scientists have recently pinpointed the types of cells the virus appears to attack.

He told Sky News that goblet cells and ciliated cells are the ones most affected by the coronavirus.

They are responsible for keeping the inside of the lungs moist and clearing them of any debris like dust or bacteria.

'The problem we've got here is the virus infects these cells and starts to kill them,' Professor Fielder said.

'And as it kills them as part of its replication process, tissue falls into the lungs, and the lungs start to get blockages. And that blockage might mean that the patient develops pneumonia.'

This could trigger pneumonia as the viruses and dead tissue clog up parts of the lungs and make them swell up, producing fluid which can block breathing.

The immune system can also worsen the symptoms of COVID-19 by going 'haywire' and damaging healthy tissue in its attempts to stop the virus, Professor Fielder said.

He told Sky: 'It can actually almost over attack, and become what we call hyperimmune, and set up a large attack which can then start to damage the healthy tissue underneath.'

The coronavirus may also damage other internal organs as it takes hold in the body.

Researchers have found signs that coronavirus patients have had damaged livers and kidneys, but there is little evidence to prove the virus caused it.

Lung problems can reduce the amount of oxygen which circulates through the body, Dr James Cherry at the University of California, Los Angeles told Healthline, in turn starving organs like the kidneys of the oxygen they need to function properly.

Organ failure is a serious health emergency and can kill if it's not repaired quickly.

Dr Laura Evans, from the University of Washington, added that a 'good proportion' of people with severe coronavirus infections developed problems with other organs. 

Coronavirus attaches to human cells by deceiving an enzyme which can make it 'fuse' to proteins inside the body and cause the infection

 Coronavirus attaches to human cells by deceiving an enzyme which can make it 'fuse' to proteins inside the body and cause the infection

In little over a month more than 10,000 people have been tested for coronavirus in Britain, of which 36 came back positive

In little over a month more than 10,000 people have been tested for coronavirus in Britain, of which 36 came back positive

Coronavirus explained: What are the chances I will die? How do I avoid it? Is it all a big fuss over nothing? World experts answer your questions 

It’s hard not to feel a sense of impending doom when reading about the coronavirus infection that is rapidly sweeping the globe. 

Figures show it has killed more than 3,000 and infected almost 90,000 people in at least 65 countries.

The majority of infections and deaths are in the Hubei province of China, where the never-before-seen virus emerged at the end of December. 

But in , nearly 5,000miles (8,046km) from the source, cases have surged, forcing some northern towns – home to 55,000 people – into lockdown.

Twelve Italians have died so far, and on Friday the first British fatality, a passenger aboard the Diamond Princess cruise liner quarantined in Japan, was reported.

In the UK, of the more than 11,000 who have been tested for the virus, 36 have been diagnosed. No deaths on British soil have been recorded.

Plans are in place to close schools, disrupt public transport and postpone major sports events, if the situation turns into a crisis. 

But for now, leading experts are urging the public to prepare and take measures to help prevent the spread of illness.

The world wants to know what to do about it and so – from risks to the elderly or ill and how to self-quarantine, to what ordinary people can do to protect themselves – we asked some of the world’s leading experts for answers to the big coronavirus questions.

A woman pictured with a medical mask covering her face. The only reason to wear a mask in public is if you think you are infected – to protect others (file photo)

A woman pictured with a medical mask covering her face. The only reason to wear a mask in public is if you think you are infected – to protect others (file photo)

How do you catch this virus?

Covid-19 seems to spread much like flu, through coughs and sneezes. Once contracted, it lives and replicates in the tissues that line the airways. Secretions from these tissues – mucus and saliva – therefore also contain the virus. When an infected person coughs, sneezes, or simply talks, tiny droplets of moisture are expelled into the air, carrying the virus out of the body. Unless you are directly in the firing line, you should be safe. Droplets travel only up to 7ft.

Struggling: Pope Francis wipes his nose as he takes part in the penitential procession on Ash Wednesday in Rome, Italy, on February 26. He said yesterday he was only suffering from a cold

Struggling: Pope Francis wipes his nose as he takes part in the penitential procession on in , , on February 26. He said yesterday he was only suffering from a cold

But another risk comes when people cover their cough or sneeze with their hand and then touch something other people touch, such as a door knob or tap. Touch a contaminated surface, then touch your own mouth or nose, and the virus can be transmitted.

The World Health Organisation (WHO) says the coronavirus can live on surfaces for several days.

Günter Kampf of the University of Greifswald in Germany says such viruses can be killed by disinfectants such as alcohol or bleach – but many things we touch every day on transport or in public buildings are not frequently disinfected.

If 14 per cent of those infected develop a severe disease and five per cent of them are critically ill, it could be a 'massive threat' according to an interview Dr Peter Openshaw, professor of experimental medicine at Imperial College London, gave The Times. 

'It doesn't present like a common cold and the symptoms can range from completely unapparent to serious disease to going into intensive care. 

'From what we have learnt so far, it seems that virus shedding - the transmission stage from infected persons - is going on relatively early during the course of infection.

'Tests can quite often become negative but then sometimes go positive again,' he said.

According to Alistair Miles, head of epidemiological informatics, Wellcome Centre for Human Genetics, we should stop touching our faces. 

He told The Times: 'Stop touching your face. Especially stop touching your eyes, nose or mouth. 

'Wash your hands often, especially before eating or touching food. 

'While a mask seems like a good idea, there isn't a lot of good evidence that it can reliably prevent infection when worn by the public. But they are useful to put on a sick person to reduce their spreading of the virus.'  

He said: 'It looks unlikely this will be over quickly. It may be with us into next year and might eventually become a seasonal infection, returning each winter.' 

Could I die if I get it?

It depends to some extent on how old you are. Covid-19 barely even causes symptoms in children, even babies, and in China is not known to have caused any deaths in under-tens. The main concern with children is that if they catch the virus they may pass it on to older at-risk individuals. This is why some headteachers have chosen to close schools, but this is not yet official policy.

According to the most recent data from the China Centre for Disease Control, death rates are 0.2 to 0.4 per cent between the ages of ten and 50, but then start climbing.

Deep cleaning: A worker in a protective suit disinfects a tram car in Pyongyang, North Korea, on February 26. Symptoms of Covid-19 are a fever, a cough or trouble breathing

Deep cleaning: A worker in a protective suit disinfects a tram car in Pyongyang, North Korea, on February 26. Symptoms of Covid-19 are a fever, a cough or trouble breathing 

You have a 1.3 per cent chance of dying from it in your 50s, a 3.6 per cent risk in your 60s, an eight per cent risk in your 70s, and a 14.8 per cent risk in your 80s.

Risk climbs with age because older people more often have other diseases, such as cancer or conditions such as high blood pressure, diabetes or pulmonary disease, which worsen Covid-19.

Professor Neil Ferguson, on the faculty of medicine at Imperial College London, told The Times: 'China seems to be suppressing transmission at the moment. In we think there are many thousands of cases distributed across the country. In Iran there are tens of thousands, if not more. 

'We calculated with an enormous amount of uncertainty that one per cent of those infected might die - with a fourfold margin of error in each direction. So a death rate of 0.25 per cent of cases would be similar to the 1957 and 1968 influenza pandemics while a four per cent rate would compare with the 1918 Spanish flu epidemic (with a death toll estimated at 40 million to 50 million).  

I have a horrible cold – could it be coronavirus?

Symptoms of Covid-19 are not like those of a cold: it causes a fever, a cough and trouble breathing, not a runny nose or congestion. Most cases appear to be mild.

If it’s mild, could I have the virus and not know it?

The short answer is yes. Although at present only those who have been in contact with people known to be infected or who have been to a high-risk area (a full list of these locations comes later) should ask about being tested.

Expert warnings about bats ignored for years

This kind of virus was, until recently, found only in East Asian bats – and it doesn’t harm them.

The virus is thought to have got to humans via bats sold in Chinese markets for food or traditional medicine, or via some other species also sold in the markets. Chinese scientists and some foreign colleagues have been warning for years that these bats were a risk.

The first human cases were in December, in people with links to a wildlife market in the city of Wuhan: many worked there. After an initial attempt by local officials to hush up the outbreak, China launched a massive effort to contain the virus, shutting down Wuhan, which is bigger than London.

In the Hubei province, where Wuhan is, case numbers now seem to be falling.

But in a globalised economy with close trade and travel links, it was impossible to stop the virus getting out.

It takes from two to 14 days after being infected by the virus to show symptoms – the average is five days. Chinese scientists say 80 per cent of all cases are quite mild. Some victims have barely any symptoms at all, so if you get sick you might not realise it’s Covid-19.

Worryingly, it seems to be possible for people to spread it before they start showing symptoms – or even if they never do. Scientists at the Guangdong Centre for Disease Control and Prevention in China found one Covid-19 patient who showed no symptoms but had as much virus in his nose as people who had symptoms.

In Germany, a woman with very mild symptoms – not enough to make her or anyone else suspicious – passed the virus to two people who shared a meeting room with her, who then passed it to two more people before they got symptoms.

During the 2002 outbreak of severe acute respiratory syndrome, or SARS, it was discovered that people were infectious – with a high enough concentration of the virus in their fluids – only after they developed symptoms.

This meant that isolating patients, to stop it spreading, was more straightforward. This time, ‘if people are infectious and spreading the virus before symptoms, then containment becomes much more difficult,’ warns Caroline Buckee of Harvard Medical School in the US.

There have been these outbreaks before, like SARS, and we got through it. Do we really need to worry now?

Experts have urged the public not to panic – however, people are being advised to stay informed.

SARS infected more than 8,000 people and killed nearly 800 in 29 countries in less than a year.

It went away because it spread poorly among people, and only after symptoms started.

Safe: Airport staff check the temperature of a passenger travelling from Milan, Italy, as part of the coronavirus screening procedure at the Debrecen airport in Hungary

Safe: Airport staff check the temperature of a passenger travelling from Milan, , as part of the coronavirus screening procedure at the Debrecen airport in Hungary

There was also a massive global campaign, led by the WHO, to isolate people who had been exposed.

‘It took a lot of hard work,’ says David Heymann of the London School of Hygiene and Tropical Medicine,

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