Health·CBC Explains

What we know (and don't know) about the new coronavirus outbreak

While the World Health Organization has declared the new coronavirus a public health emergency of international concern, the risk of contracting the illness in Canada remains low.

6 common coronavirus questions answered from a Canadian perspective

Information about the coronavirus outbreak is spreading fast, but what do we actually know about the illness? CBC News medical contributor and family physician Dr. Peter Lin breaks down the facts about what it is, where it came from, how it spreads and what you can do to protect yourself. 5:10

The recently identified coronavirus has spread beyond its starting point in the central Chinese city of Wuhan to impact other parts of Asia, as well as Europe, North America and Australia.

Canada confirmed its first presumed case on Jan. 25, followed by two more in Ontario and one in British Columbia.

The World Health Organization (WHO) on Thursday declared the outbreak a public health emergency of international concern based on the potential for the virus to spread to countries with weaker health systems. 

Canadian public health officials stress that the risk of contracting the illness in this country remains low. They've asked the general public to be vigilant and for health-care workers to prepare to care for infected patients.

Here is what we know — and what we don't know — about the virus. 

People wear masks out of concern over the coronavirus at the terminal that serves planes bound for China, at John F. Kennedy Airport in New York City on Friday. (Spencer Platt/Getty)

What is coronavirus?

Coronaviruses are a large family of viruses. They cause a range of illness ranging from the common cold to more severe diseases — such as Middle East Respiratory Syndrome (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS-CoV).

SARS was the coronavirus that originated in China in late 2002, and which eventually killed 44 people in Canada and infected more than 400 before the outbreak in China was declared by the WHO to be "under control" on Apr. 28, 2004. 

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      Where did this new coronavirus come from?

      The WHO's China office was first informed of cases of pneumonia with an unknown cause on Dec. 31, 2019. The cases were all detected in Wuhan City.

      A new coronavirus (2019-nCoV) was identified as the probable cause by Chinese authorities Jan. 7. The WHO reported the evidence was "highly suggestive" that the source was a seafood market that also sells live poultry and meat from exotic animals in Wuhan.

      How is it transmitted?

      Coronaviruses are zoonotic, meaning they originally pass from animals to humans. But some, like this newly identified strain, can pass directly between humans.

      Chinese scientists confirmed there has been human-to-human transmission of the virus among close contacts such as family members. It's unclear how easily the virus is transmitted between people.

      According to the Centers for Disease Control in the U.S., coronaviruses are most commonly spread by coughing or sneezing; close personal contact, such as shaking hands; or touching an object or surface with the virus on it and then touching your mouth, eyes or nose. 

      A doctor puts on protective goggles before entering the isolation ward at a hospital in Wuhan, China on Thursday. (China Daily/Reuters)

      What are the symptoms?

      The initial symptoms of 2019-nCoV are mainly fever, with a few reports of people having difficulty breathing, and chest x-rays showing signs of pneumonia in both lungs.

      According to the WHO, signs of infection can include respiratory complaints, fever, cough, shortness of breath and breathing difficulties. In more severe cases, infection can cause pneumonia, severe acute respiratory syndrome, kidney failure and even death. 

      The only way to confirm 2019-nCoV is with a lab test.

      Should Canadians be worried? 

      The Public Health Agency of Canada (PHAC) deems the risk to Canadians visiting Wuhan as low. But it has updated its travel advisory, urging Canadians to take precautions, such as avoiding large crowds and high-risk areas such as farms and slaughterhouses, and avoiding contact with anyone who is exhibiting symptoms of a coronavirus, such as fever, cough or difficulty breathing.

      PHAC has signs at airports in Toronto, Vancouver and Montreal, advising travellers from affected areas of the world to inform border services staff of any flu-like symptoms. If so, travellers are advised to call ahead to health-care professionals.  

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      What we don't know yet

      The newly identified coronavirus has created alarm because there are a number of unknowns surrounding it. It is too early to know just how dangerous it is and how easily it spreads between people.

      Early on in an outbreak, not everyone who is infected seeks or needs medical attention so officials won't have a clear picture of mild illness.

      Not knowing the full spectrum makes it hard to estimate the fatality rate. But public health experts say early research suggests that the new coronavirus is less deadly than other infectious diseases.

      Analysts predicted cases will continue to multiply, although the jump in numbers is also attributable in part to increased monitoring. Dr. Gauden Galea, the WHO's representative in China, said the number of infected is not an indicator of the outbreak's severity so long as the death rate remains low. 

      Chinese authorities have moved to lock down multiple cities — including Wuhan, where the train station and airport were shut down and ferry, subway and bus service was halted. In Beijing, officials cancelled major events indefinitely, including traditional temple fairs that are a staple of holiday celebrations in the capital.

      WATCH | An infectious disease physician on what Canadians should be aware of:

      Infectious disease specialist says risk to Canadians is low 0:46

      Chinese officials have not said how long the shutdowns will last. While sweeping measures are typical of China's government, large-scale quarantines are rare around the world — even in deadly epidemics — because of concerns about infringing on people's liberties. The effectiveness of such measures is also unclear.

      There is no specific treatment or vaccine yet for the virus.

      Notable quotes:

      The main reason for this declaration is not because of what is happening in China but because of what is happening in other countries.

      Our greatest concern is the potential for this virus to spread to countries with weaker health systems which are ill-prepared to deal with it.

      - WHO Director-General Tedros Adhanom Ghebreyesus 

      To my knowledge, trying to contain a city of 11 million people [Wuhan] is new to science.

      - Gauden Galea, WHO representative in China.

      We don't know enough to know whether we should be worried … If this is a virus that can sustain itself in humans now  is transmitted from person to person and lives in humans  then the Lunar New Year travel will spread it faster in China, no doubt. If this is a virus that is not sustainable in human populations, if it doesn't transmit well enough, then the Lunar New Year means we'll see new cases, it will create a lot of concern, but it won't cause problems. 

      - Dr. Allison McGeer, infectious disease specialist, Mount Sinai Hospital in Toronto

      (CBC News)

      With files from The Associated Press and Reuters