Canadian health officials are asking travellers who have returned from the Hubei province of China to go into voluntary self-isolation for up to 14 days — even if they show no symptoms of the coronavirus.

The request represents an escalation of health officials' response to the outbreak. Up to now, health authorities have advised travellers returning from the epicentre of the outbreak to monitor their health and seek medical attention at the first sign of symptoms.

But as new data reveal more about how the virus is spread — and how early symptoms can be misidentified — the federal government is changing its advice.

"It is possible that people will not know when they first develop symptoms because they can be very similar to a cold or a flu," Health Minister Patty Hajdu said Thursday. "If you have travelled to Hubei province in the last 14 days, limit your contact with others from the date that you left Hubei. This means self-isolate and stay at home."

The self-isolation period starts the day a traveller leaves Hubei province — so many people who've returned recently from Hubei may already have passed the recommended isolation period without showing symptoms.

Hajdu said the advice being given to travellers at airports is being updated to reflect this recommendation. Travellers coming from other parts of China are being asked to follow the initial health instruction of monitoring themselves for symptoms.

A man wearing a face mask and a plastic bag as a glove walks past empty shelves in a supermarket in Hong Kong, Friday, Feb. 7, 2020. In recent days, residents have been buying large amounts of products because they fear that border restrictions, which were enforced to control the coronavirus outbreak, may affect supply flows into Hong Kong. (Kin Cheung/The Associated Press)

Canada's move comes as the large-scale quarantine efforts underway in China hit a critical point. This particular coronavirus is believed to have an incubation period of about 14 days. It's been about two weeks since China locked down the province of Hubei — which includes the city of Wuhan and has a population of nearly 60 million people.

"This is actually a quite important period and in the next days, we hope to see if there's any signs that some of these measures may be beginning to take effect," said Chief Public Health Officer Theresa Tam. "Out of precaution and total amounts of prudence, if you like, we feel that this is the right message."

Health officials are quick to stress that this policy of voluntary self-isolation is not a response to any heightened risk here in Canada. The federal government still says the risk to Canadians is low.

Officials haven't said how many people this voluntary isolation might affect, though they believe it is likely to be a small number because of the strict travel restrictions China imposed on the Hubei region and the sharp reduction in flights there since the outbreak.

The voluntary isolation request stops short of the mandatory quarantine required for Canadians evacuated to the CFB Trenton military base from China by the federal government.

The Public Health Agency of Canada says that's because those evacuees — most of them removed from Wuhan — were trapped in the region with the highest concentration of coronavirus cases over a longer period of time.

"Their risk of exposure and potential illness is increased compared to other recent travellers coming to Canada from China," a Public Health Agency spokesperson said in an email. "As a precautionary step, individuals returning on the special flight to Canada will remain at CFB Trenton for further health assessment and observation."