An intensive-care expert has demonstrated just how infectious the new coronavirus is, as people are urged to self-isolate across the world.

A person with the common flu will on average pass it to 1.4 people, Professor Hugh Montgomery told Channel 4's "Dispatches" on Sunday. If there are 10 cycles of that interaction, there will be 14 cases of the flu, he calculated.

But the coronavirus is three times as infectious as the flu. So if one person with the coronavirus passes it onto three people, and those three people pass onto three more people for ten cycles, there will be 59,000 infections, he said.

"If you are irresponsible enough to think that you don't mind if you get the flu, remember it's not about you, it's about everybody else," Montgomery said.

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An intensive-care specialist has broken down just how infectious the new coronavirus is, illustrating the importance of self-isolating to slow the spread of the COVID-19 disease around the world.

Professor Hugh Montgomery, director of the Institute for Human Health and Performance at University College London, told Channel 4's "Dispatches" that the virus is three times more infectious than the flu, and therefore spreads much faster and wider.

"Normal flu, if I get that, I'm going to infect on average 1.3, 1.4 people ... by the time it's happened 10 times, I've been responsibly for about 14 cases of flu," Montgomery said.

This figure comes from calculating 1.4 to the power of ten, which yields 13.786.

"This coronavirus is very, very infectious, so every person passes to it three, now that doesn't sound like much of a difference, but if each of those three pass it to three and that happens in 10 layers, I have been responsible for infecting 59,000 people."

This figure it from raising three to the power of ten, which yields 59,059.

—Channel 4 Dispatches (@C4Dispatches) March 22, 2020

Governments in countries including China, South Korea, France, Italy, the UK, the US, and Spain have been told to stay at home and self-isolate to stop the coronavirus from gathering momentum.

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Most of the deaths caused by the coronavirus have been observed in the elderly and those with underlying health conditions.

Montgomery also warned people against being complacent, saying: "If you are irresponsible enough to think that you don't mind if you get the flu, remember it's not about you, it's about everybody else."

A rendering of the COVID-19 virus.

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Tedros Adhanom Ghebreyesus, the director-general of the World Health Organization, has previously warned that it is unwise to compare the virus and the flu in terms of its effects on society.

"This virus is not SARS, it's not MERS, and it's not influenza. It is a unique virus with unique characteristics," he said.

However, the flu and COVID-19 do have some similar symptoms, like a sore throat, fatigue, and a dry cough. People with COVID-19, however, don't typically have runny noses or sneeze a lot.

The coronavirus' ability to spread quickly was observed in South Korea with the case of "Patient 31."

In mid-February, a 61-year-old woman in Daegu, now known as "Patient 31," was deemed responsible for causing 70 of South Korea's 104 infections after heavy socializing at a church event, Reuters reported, citing Korea's Centres for Disease Control and Prevention (KCDC).

South Korea now has more than 8,900 cases and 111 deaths, but the spread of the virus has been significantly slowed by stringent isolation and lockdown measures.

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