‘You could literally go around the Earth’ before symptoms start: Screening for new coronavirus

Medical screening at airports, border crossings and health-care institutions takes on new urgency when a viral threat looms.

Tuesday’s announcement of the first infection in the U.S. — a man who returned to the Seattle area last week after travelling to the outbreak’s epicentre in Wuhan, central China — adds to more than 400 people infected with the new coronavirus, which has sickened people in China as well as Thailand, Japan and South Korea.

U.S. health officials will expand airport screening from New York, San Francisco and Los Angeles to Chicago and Atlanta.

The Public Health Agency of Canada acts as the lead agency for the coronavirus through the Quarantine Act.

As part of the federal government’s response, Canada Border Services Agency officials will ask travellers: “Have you been in Wuhan, China in the past 14 days?” There are no direct flights from Wuhan to Canada.

Additional signs at airports in Toronto, Montreal and Vancouver will remind passengers to speak to border officials if they have flu-like symptoms such as fever and cough.

“We are in the process of putting up signs on the electronic screens warning travellers that if they’ve been to an affected area to essentially determine if they’ve been in contact with live animals, sick people,” Dr. Theresa Tam, Canada’s chief public health officer, said Tuesday on CBC’s Power & Politics.


If so, CBSA agents can alert a federal quarantine officer to do an assessment, which could include a temperature check.

“The current assessment of the risk to Canada is low,” Tam said.


Health officials watch thermographic monitors at a quarantine inspection station at the Kuala Lumpur International Airport in Malaysia on Tuesday in the hope of identifying passengers infected with the new coronavirus. (Vincent Thian/The Associated Press)

Dr. Vanessa Allen, chief of medical microbiology at Public Health Ontario, said three potential cases in the province were investigated and ruled out.

“We were aware of the link,” Allen said. “Co-ordinated calls were arranged by the ministry and we discussed the cases and the three individuals more subsequently tested. So they all had, you know, some degree of a link to Wuhan with respiratory symptoms. We did in fact test in an abundance of caution.”

Canada’s National Microbiology Laboratory as well as provincial government labs in Ontario, British Columbia and Alberta have a battery of tests to detect respiratory pathogens, including one that’s in the works for the new coronavirus, Allen said.  

Temperature checks and SARS lesson

So far, Canada is not planning to use thermal imaging to monitor travellers en masse as was tested during the 2002-03 outbreak of severe acute respiratory syndrome or SARS that affected nearly 8,100 people and caused 774 deaths, according to the World Health Organization.

Steven Hoffman, a law professor and director of the Global Strategy Lab at Toronto’s York University, an expert on global health, supports Canada’s screening approach so far.

“Not everyone who has a high temperature is going to have this novel coronavirus. In fact, only a very small percentage would,” said Hoffman.


Dr. Kamran Khan, an infectious disease physician, says the most important point of screening travellers is ‘giving them the information they need so that if they do become sick after they’ve left the airport they know what to do.’ (John Lesavage/CBC)

It’s also important that health-care systems in Canada prepare.

“There’ll likely be a case in Canada at some point. But the key then is once you have cases how much are you able to contain it before it further spreads,” Hoffman said.

The first U.S. patient illustrates one of the weaknesses of airport screening — the man in his 30s did not have symptoms when he arrived and was in good condition, so he wouldn’t be picked up in a check for fever.

Rather, when the man started feeling ill, he went to a doctor, with a fever and cough. Lab tests confirmed the infection and he was put into isolation for monitoring.

Engaging travellers

Dr. Kamran Khan, an infectious disease physician in Toronto, said there’s a time between when people are infected and when they develop symptoms — the incubation period. For coronaviruses in general, such as those that can cause the common cold, the incubation period is typically five or six days.

With coronaviruses such as SARS and Middle East Respiratory Syndrome, MERS, the incubation period can extend to two weeks.

“You can imagine if an individual is infected and they get on a plane and it could be up to two weeks before they manifest symptoms. In today’s world you could literally go around the Earth before you start to develop illness,” said Khan, founder and CEO of BlueDot, a digital health company that helps predict the spread of infectious diseases globally.

“We need to kind of think about that in the context of how airport screening works. The value of airport screening and engagement with travellers, if you will, is more about giving them the information they need so that if they do become sick after they’ve left the airport they know what to do.”

Tam called the airport measures one layer of protection on top of alerting health systems to be on the lookout for travellers who may be infected.

Otherwise, health officials are stressing precautions for travellers to  prevent the infection while in China, such as staying away from animal markets, washing hands, observing cough hygiene, not contacting sick people and telling health-care providers about their travel if flu-like symptoms occur.

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