Hajdu stressed the need and the responsibility to remain calm.
Dozens of people across Canada are being tested for the new coronavirus, including 27 in Ontario.
"The problem is a virus - it's not human beings, it's not countries, it's not aircrafts, it's a virus", she said, urging people to trust Canada's public health workers.
There are 27 cases now under investigation in the province, and 38 people have already been tested and cleared.
Health officials are asking anyone who has recently travelled to the city of Wuhan in China's Hubei province - or been in contact with someone who has - to call ahead to local hospitals to bypass the emergency room in order to receive treatment in isolation.
Elsewhere in the world, health officials in India and Phillipines say they detected the countries' first cases of the novel coronavirus.
The province's two confirmed case are a middle-aged couple who returned to Toronto from the Wuhan area of China last week.
Also Wednesday, Toronto council and leaders from the city's Chinese-Canadian community held a news conference urging the public not to stigmatize or associate the community with the virus.
Travel Alberta, which works to promote tourism to the province, says it's hearing about cancellations of Chinese tourists to Canadian hotspots including Banff and Yellowknife.
"We've seen too many instances of unreasonable fears being spread either on the internet or in other ways. We need to know this is a time for Canadians - all Canadians, including Canadians of Chinese origin - to pull together and to lean on each other", Trudeau told reporters in Brampton, Ont.
"Individuals of concern have self-reported ... and we haven't seen anyone come out of the blue show up already quite ill", he explained.
A federal lab has confirmed the earlier finding of a second case of the 2019 novel coronavirus in Toronto, while Ontario public health officials are investigating 23 other people for possible infection.
A total of 67 people have been tested for the new coronavirus across Ontario.
Instead, he suggested people practice "respiratory hygiene" by washing their hands and covering their mouths when sneezing or coughing.
-With files from The Associated Press.