EDMONTON -- The Misericordia Community Hospital is now closed to new patients and postponing day procedures and visits due to the growing COVID-19 outbreak at the west Edmonton facility.

Alberta Health Services announced Wednesday the Misericordia is under "full facility outbreak" after 20 patients — two more since Monday — and 15 staff have tested positive for the coronavirus.

Three people have died after contracting the virus at the hospital.

READ MORE: 3rd death reported at Misericordia amid ongoing COVID-19 outbreak

"This step is a necessary extension of the progressive outbreak restrictions put in place on July 6, with those restrictions now encompassing all patient services at the Misericordia," the AHS release read.

Restrictions include limiting visits to those patients already in the hospital in end-of-life situations, AHS said.

"This obviously has a number of significant interventions when a facility goes on facility outbreak," said Dr. David Zygun, the medical director for AHS Edmonton Zone.

The hospital has cancelled surgeries and outpatient appointments and moved labour and delivery service to Grey Nuns Hospital.

The emergency ward remains closed.

"All hospitals have come together to ensure patient care is continued to be delivered," said Zygun.

AHS is performing "extensive" contract tracing to get to the bottom of the outbreak, but preliminary work suggests it's likely to have been caused by multiple factors.

He said it appears the initial wards where the outbreak occurred were medicine wards.

Zygun said medical staff at the hospital are being reminded to remain vigilant about daily fit-for-work screening, wearing PPE, practising proper hygiene and continuous masking.

"We can also ask for, and really would be helpful if the public can continue to assist us as they have through this pandemic," he said, pointing to existing public health orders like two-metre physical distancing.

Asked about reports that some nurses felt the hospital was understaffed, Zygun said AHS believed the staffing was adequate at this time.

Regarding concerns that the hospital closure could put a strain on other Edmonton hospitals, he said the province's pandemic planning including holding acute care beds for a possible influx of COVID-19 patients.

"We continue to have that in reserve, both in the zone and in the province," he said. "We're opening up some of that capacity for this COVID response."

An infectious disease expert says concerns the virus may have been spread via airborne microdroplets are overblown.

"I don't think that's really a plausible means of transmission and very highly unlikely," said University of Calgary's Dr. John Conly. "There's many other likely means of transmission including close contact through hands or fomites were transmission may have occurred."

As for additional steps that could be taken by the hospital to mitigate the outbreak, Conly said it was only "a tincture of time."

"You moved through, and this is standard type of process that's being followed, through different phases," he said. "Once you've closed it to admissions it gives you an opportunity to be able to deal with those patients who are infected and those health care workers so they can be furloughed."

He said the closures will allow the hospital to deal with the outbreak more effectively.

Alberta's COVID-19 case count rose by 46 on Wednesday to a total of 8,482, while 158 people have died from the disease in the province.