EDMONTON -- As part of a new aggressive measure to fight the coronavirus pandemic, Alberta is cancelling all large gatherings and advising against international travel.

After announcing four new COVID-19 cases Thursday afternoon, the province is asking organizers to cancel gatherings of 250 people or more.

These large gatherings include sporting events, conferences and community events, but not places of worship, grocery stores, shopping centres or airports, the province said.

"These are extraordinary circumstances, and our public health measures must rise to the challenge we face," Alberta's top doctor, Deena Hinshaw, said.

Schools and daycares can also remain open, the province said. Earlier Thursday, Ontario decided to close public schools until April 5.

"That's a decision that we're considering," Hinshaw said. "At this time, we haven’t made a decision … at the moment we have no evidence of any school in the province where there has been a confirmed case of COVID-19."

Montreal has decided to close all public facilities that hold more than 250 people, including community centres and libraries.

Sports leagues and large events across the world are also taking action to prevent more coronavirus spread. The NHL, NBA and MLS have suspended their seasons, and MLB pushed back its start by two weeks.

MORE CORONAVIRUS CASES IN ALBERTA

The province announced four new COVID-19 cases, bringing the total to 23.

All four new cases are from the Calgary zone: a two-year old child, a man in his 50s, a woman in her 30s and a woman in her 70s.

The child recently returned from Florida, and after attending daycare from March 2 to 6, is now recovering at home, the province said. The child is expected to make a full recovery.

"I want to assure all parents that cases of COVID-19 in children are typically mild," Hinshaw said.

All cases are still travel related. The most recent patients travelled to Jordan, Egypt, France and Germany.

There are 15 cases in the Calgary Zone, seven in the Edmonton Zone and one in the Central Zone.

NEW TRAVEL RECOMMENDATIONS

The province is advising Albertans against travelling internationally.

"Given the rapid spread of this virus, it is no longer possible to assess health risks for the duration of the trip," Hinshaw said.

She is also recommending all Albertans currently outside of Canada to self-isolate for 14 days after their trip.

Hinshaw said the risk of contracting coronavirus in Alberta has not changed in the past 24 hours, but is concerned that international travellers will continue to bring the disease into the province.

"Given the global spread and our ongoing work to aggressively identify and isolate cases of COVID-19, I expect that we will continue to confirm new cases in the days ahead."