TORONTO -- The CEO of Toronto’s University Health Network (UHN) made a direct appeal to thousands of onsite staff members on Monday, who have yet to go get their COVID-19 vaccine, calling their decision “worrisome” amid a third wave of the disease.

“This message is a special and heartfelt request for us all to be vaccinated,” Kevin Smith said in a letter sent to all staff members.

“This is all the more worrisome as we see a third wave beginning and the rapid rise of variants, which make COVID-19 much more infectious and possibly more severe and deadly. While our overall rate of uptake is very good, there are areas and programs where vaccination remains below 50 per cent of people. We must change this immediately.”

In the letter, Smith says that while more than 17,000 members of UHN have received at least one dose of a COVID-19 vaccine, there are about 4,000 people who work regularly onsite that have not.

The majority of people who have gotten the vaccine provide care in emergency departments and intensive care units.

Smith makes reference to “rumours about the vaccines” in his letter and said that health service vaccine ambassadors will be made available at each unit to answer questions.

“We have the privilege and the inordinate responsibility of caring for Canada‘s sickest citizens,” he said. “Nowhere more than here must we see maximal uptake of these safe and effective vaccines. Our own research has contributed not only to their creation, but also to our confidence in their safety and effectiveness.”

On Tuesday, Gillian Howard, a spokesperson for UHN, confirmed that since the letter was sent, an additional 1,000 people have registered for the vaccine. This means that about 85 per cent of staff at UHN will soon be vaccinated, Howard added.

According to Infectious Disease Specialist Isaac Bogoch, an 85 per cent vaccination rate is “a pretty sound number.”

“You want it as close to 100 per cent as possible, but like anything else, it's not going to get to 100 per cent,” Bogoch said.

“If you're looking at rates of vaccination that are over 85 per cent, you're clearly doing something good, but there's still of course room for improvement. I mean we know COVID-19 is a very transmissible infection, we know that the vaccines are safe and effective.”

Bogoch added that the problem isn’t limited to one hospital network, rather it’s an issue across the health-care system.

“This is a health-care providers’ story,” he said. “The exact same thing is happening in hospitals and health-care settings around the world. This is but one of an infinite number of examples.”

“There's going to be different degrees of uptake within different communities in the health-care community … it's a very diverse community, lots of different people from lots of different backgrounds, with lots of different areas of expertise.”

Bogoch said that while there are a few groups within the health-care system that may be hesitant to get the vaccine, they are not the majority and that concerns should be approached in an empathetic way.

In Ontario, more than 1.6 million people have received at least one dose of a COVID-19 vaccine while a little more than 301,000 people have received both doses and are considered immunized.

On Tuesday, Premier Doug Ford said the province recorded a record number of vaccinations in the last 24-hour period, with more than 72,000 shots administered.