What the WHO learned about COVID-19 on its research mission to China

OTTAWA — Renowned Canadian epidemiologist Dr. Bruce Aylward led a team of researchers into China earlier this month to study the novel coronavirus on behalf of the World Health Organization. Here's what you need to know about their newly released discoveries:

What are the symptoms?

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The novel coronavirus can cause a respiratory illness, called COVID-19, that can present very differently from person to person. Some show no symptoms at all, while others have developed severe pneumonia and even died. So far the disease has killed 2,800 people worldwide. The most common symptoms are fever and a dry cough. Less commonly, people with the disease showed signs of shortness of breath (less than 20 per cent of cases) or a sore throat (less than 14 per cent). Only five per cent of cases showed symptoms of nausea. Nasal congestion was even less common.

How will it affect your kids?

There are still many unanswered questions about how the virus affects children, including whether they are less susceptible or if they present with different or milder symptoms. Researchers did learn the attack rate in China appeared lower in people 18 and younger, representing only 2.4 per cent of the total number of cases. They also noted no one they interviewed could recall a situation when an adult was infected by a child. Usually, cases of the virus in children were discovered by testing the close contacts of infected adults. Only a very small percentage of people younger than 19 who contracted the disease developed a severe or critical case.

Who is most at risk?

Because there's no known pre-existing immunity to the virus in humans, everyone is assumed to be susceptible. Most people who are infected will only get a mild or moderate case, which may or may not include a pneumonia, but in China about six per cent of cases were considered critical. The people at highest risk for severe disease and death are those over 60, and people with underlying health conditions like hypertension, diabetes, cardiovascular disease, chronic respiratory disease and cancer. Health-care workers have also been impacted by the virus, especially in the central Chinese city of Wuhan, where the outbreak began. Most cases happened early on, before there was much experience with the disease.

How is it transmitted?

In China, transmission is largely happening in families. Community transmission has been very limited. The researchers found the virus is transmitted mainly through droplets from coughing or sneezing, though more study is needed about the potential for airborne transmission outside of hospitals. The virus has also been found in fecal matter. That's not been driving transmission in China, the researchers said, but it's role and significance for COVID-19 remains to be determined. During the 2003 SARS outbreak, the WHO says officials found the virus spread to residents of a Hong Kong apartment building called through faulty plumbing.

What is the incubation period?

People generally develop symptoms within five to six says of being infected, but researchers said it can range from one to 14 days. That is why the government has quarantined people returning from places with high concentrations of the virus for two weeks. Asymptomatic cases have been reported, but most went on to develop the disease after they were tested. Among patients who died, it took from two to eight weeks from the time their symptoms emerged.

This report by The Canadian Press was first published Feb. 28, 2020.

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