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What we know about how the new coronavirus is spread

A worker wearing a hazardous materials suit takes the temperature of a passenger at the entrance to a subway station in Beijing, Sunday, Jan. 26, 2020. The new virus accelerated its spread in China, and the U.S. Consulate in the epicentre of the outbreak, the central city of Wuhan, announced Sunday it will evacuate its personnel and some private citizens aboard a charter flight.
A worker wearing a hazardous materials suit takes the temperature of a passenger at the entrance to a subway station in Beijing, Sunday, Jan. 26, 2020. The new virus accelerated its spread in China, and the U.S. Consulate in the epicentre of the outbreak, the central city of Wuhan, announced Sunday it will evacuate its personnel and some private citizens aboard a charter flight. AP Photo/Mark Schiefelbein

The first cases of a novel coronavirus appeared in the Chinese city of Wuhan in the last days of 2019.

Then there were more cases. And then more — around 2,900 as of the morning of Jan. 27, 2020 — mostly in China, but also around the world, including two Canadian cases.

The virus is thought to have originally been transmitted from an animal to a human, according to the World Health Organization, though health officials haven’t yet been able to identify which kind of animal started the outbreak.

Since then, WHO officials have confirmed that the virus can be transmitted between people — meaning you can get it from another person, not just from animals.

READ MORE: Coronavirus — How to protect yourself

The virus, currently known as 2019-nCoV, is a coronavirus, part of a family of viruses. Some coronaviruses cause the common cold, and others are responsible for SARS (Severe Acute Respiratory Syndrome), for example.

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At the moment, experts think that the new coronavirus is likely spread like most other such viruses, said Dr. Susy Hota, an infectious diseases physician and medical director of infection prevention and control at the University Health Network in Toronto.

“Every indication that we have so far is that it’s transmitted like many other coronaviruses and other respiratory viruses through what we call droplet transmission,” she said.

“That’s generally larger respiratory secretion droplets, so things that are generated when you cough or sneeze and you’re infected with the virus.”

2nd case of ‘presumptive’ coronavirus confirmed in Toronto
2nd case of ‘presumptive’ coronavirus confirmed in Toronto

These drops will likely only spread about a maximum of two metres from the infected person, she said. “Even just passing through that range, your risk is quite low. So, you’d really have to have enough continuous exposure to somebody in that kind of close proximity to get sick.”

They can also settle onto objects, where the virus might last hours or days depending on the surface, she said.

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“We don’t entirely know with this virus how long, but if you happen to touch that surface, then your hands can get contaminated with it and you can transmit it to yourself if you touch your eyes, or your mouth or nose,” she said.

Unpacking the potentially deadly coronavirus and possible protections
Unpacking the potentially deadly coronavirus and possible protections

So far, the cases have generally been transmitted between family members after close, prolonged contact, said Dr. Theresa Tam, Canada’s chief public health officer, at a press conference Monday afternoon.

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“Canadians should not be concerned that they will pick up the virus from an infected individual by any casual contact, such as walking through the airport,” she said.

This kind of droplet transmission is different from a more airborne virus, like measles, which can remain in the air and travel much farther, Hota said.

READ MORE: Panic over coronavirus is ‘very human,’ but experts say the risk is low

Early indicators are that each person infected by the virus infects on average between 2 and 2.5 others, Hota said, a number epidemiologists refer to as the r0 value. This is much lower than measles, an extremely infectious virus, which has an r0 value of 10 or more.

Hota notes that this number is constantly changing as new information comes in, though, and even as public health officials take measures to control the spread of the disease.

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“The numbers and the estimates are constantly changing, every hour.”

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It’s also a bit early to get a good estimate of the incubation period — the length of time between exposure to the virus and when symptoms begin to show, she said.

Current estimates are between three and 14 days, she said. “You can see how a longer incubation period makes things challenging in terms of controlling infections, because people move around in that time.”

Some reports have suggested that people might be infectious before they show symptoms, though Hota isn’t completely convinced we know yet.

Tam isn’t either.

“We do obviously have to go back to have this information verified,” she said. “But so far we haven’t seen any clear evidence of patients being infectious before symptom onset.”

READ MORE: Here’s what we know about whether China misrepresented the Wuhan coronavirus outbreak

For now, Hota said, if you’re coughing or exhibiting other symptoms, it’s more likely you have another common cold or flu — not this new coronavirus.

“We’re still seeing a good amount of flu and respiratory syncytial virus (RSV), which is another common respiratory virus this time of year,” she said.

“There are more than 200 respiratory viruses that tend to circulate this time of year. You’re much more likely to get one of those infections than this novel coronavirus right now in this area.”

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To protect yourself, you should do the same kinds of things that you would do for any virus, according to the WHO: avoiding close contact with infected people, washing your hands frequently, and practising good cough etiquette — meaning covering your mouth and coughing into your elbow, rather than toward other people.