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Cough, kiss, touch: How the new coronavirus can (and can’t) spread

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COVID-19: We asked an infectious disease expert your coronavirus questions – Mar 4, 2020

Editor’s note: This story was originally published March 5. Since then, new information has come out about how the novel coronavirus spreads. We have updated the story with some of that information.

Worried about catching the new coronavirus? It’s a concern many people share, though experts say there are some simple things you can do to reduce your risk.

Here’s what you need to know about how the virus spreads, and how people catch it.

How easily does it spread?

“This virus is not SARS, it is not MERS and it is not influenza,” Dr. Tedros Adhanom Ghebreyesus, director-general of the World Health Organization, said at a press conference in March.

“COVID-19 spreads less efficiently than flu and transmission does not appear to be driven by people who are not sick.”

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While the numbers are constantly changing, the best current estimates are that each infected person will on average infect between two and four others, according to Dr. Alon Vaisman, an infection control and infectious diseases physician at Toronto’s University Health Network.

That is a bit more than influenza, but much fewer than measles, where each case might infect on average 18 other people, he said.

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How does it spread?

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“Like all other respiratory viruses, coronaviruses, this coronavirus is spread through droplet transmission,” Vaisman said.

What that means is when an infected person coughs or sneezes, they expel tiny water droplets containing the virus to a distance of about six feet away, he said. These droplets are heavy enough that they can’t stay in the air for longer than a few minutes, so they fall onto whatever is under them: a table, for example, or your arm.

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When you bring these droplets to a mucous membrane, like your eye or your mouth, that’s how you might catch the virus.

How long does it survive on a surface?

It depends on the surface, Vaisman said, but generally, the estimate is from several hours to even a few days.

“Days would be more unusual, and hours would be the more likely scenario.”

At a press conference in March, WHO officials said studies on this question were ongoing.

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However, it’s unlikely that items shipped from China would contain the virus, Vaisman said.

“That would be very, very unusual because the environment that they’re put in is a low-oxygen environment.”

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He doesn’t think the virus would survive the shipping process.

Also, he said, there haven’t ever been cases where shipping was identified as a mode of transmission.

Are there other ways you might catch the virus?

There’s not much evidence that the virus is transmitted through direct contact – like through sex, Vaisman said, though you might catch it if you kissed someone who was sick.

“It would be very unlikely, because most respiratory viruses only can infect the respiratory tract, so it wouldn’t likely be secreted in the genital tract,” he said.

READ MORE: How Canada is encouraging self-isolation to prevent the spread of COVID-19

Also, while there have been suggestions that the virus can be transmitted through fecal contact, it’s very unlikely you would get it that way unless you were a health-care worker or a close family member who was directly caring for someone who was ill, he said.

How should you protect yourself?

The best way to protect yourself is by washing your hands, according to the Public Health Agency of Canada. If the virus isn’t on your hands, it’s harder for it to get to your nose and mouth and infect you.

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People should also stay at home when they’re sick, and cough into their elbows to avoid transmitting the virus.

Masks are not advised unless you’re a health worker or, in some cases, if you’re feeling sick yourself as a way to protect others, Vaisman said.

“It’s not a great way to protect yourself from others. It’s also an unnecessary use of supplies that could otherwise go to somebody who really needs it.”

However, non-medical masks are recommended by public health officials for occasions where physical distancing is difficult, like when shopping for groceries.

Cleaning your house won’t do much good either, even if it is a nice idea, Vaisman said.

“To wash your house is not really of any relevance unless you’ve had a patient in your house who has the virus. The more important thing is to keep clean when you’re outside your home.”