TORONTO -- An Ontario doctor is urging people to get a COVID-19 vaccine once a jab becomes available to them after he admitted three patients who turned down shots to the ICU.

Dr. Alex Patel, a critical care physician in Toronto, tweeted on Wednesday that three patients who were able to get a COVID-19 vaccine, but decided not to, are now all in hospital with severe infection.

"I just admitted 3 patients to the ICU in 30 mins. All of them had qualified for the vaccine over a month ago but never got it. Sadly, all of them now have severe Covid. Please DON’T HESITATE when it’s your chance. It may be your last," Patel tweeted.

Patel told CTV News Channel on Thursday that these patients could have been inoculated against the coronavirus, but chose not to receive a jab for "various reasons."

"In this case it was because they either didn't get around to it, because they didn't sense the urgency of getting it, or they were hesitant to get it for other reasons, such as side-effects," Patel said.

He said that he has also seen other patients in the ICU who did plan on getting their vaccine, but had their appointment cancelled due to supply issues.

Patel noted that most patients he sees in the ICU have not had the opportunity to get a vaccine yet. But he said these patients could have, and likely would not have, been admitted to the ICU if they had.

Patel said the situation is "quite disheartening."

"Those patients were potentially preventable, in terms of their ICU admission and as it's been well documented in Ontario, we are running into a bit of a crisis with ICU beds and we have a lot of essential workers and patients that couldn't get vaccinated, and those people really need those beds when they get sick," Patel said.

He added that this puts additional strain on the health-care system.

"One of the issues is if you're now using those beds for people that could have got the vaccine and get sick... it's just going to make it more difficult to care for everybody," Patel said.

Ontario set a new record for daily infections on Thursday, logging 4,736 cases. The province currently has 1,932 people in hospital with COVID-19 and 659 in intensive care -- record highs as well.

After being admitted to the ICU, Patel said it was evident that the patients and their families wished they had gotten their vaccines when they had the chance.

Patel explained to them that serious COVID-19 infection can be preventable with the vaccine, and encouraged them to get the shot.

"I do think that a lot of them, if they had the opportunity to do it again, may have chose differently," Patel said.

For those who are hesitant about being vaccinated, Patel said provincial leaders and health officials need to address what is making these people feel wary.

One of the main reasons Patel said he hears from people who are hesitant is that they find it too difficult to book an appointment. Patel says this is a major problem.

"I think if that's the situation, you should help your elderly parents or other people to try and navigate the system. Hopefully, the Ontario government makes it a bit easier going forward, but until they do we have to kind of pitch in and help," he said.

Another reason why some are hesitant, Patel says, is because younger people believe they’re healthy enough to fight off the virus and won’t be impacted the same way as an older COVID-19 patients.

While this may have been true during Canada's first wave of the pandemic, Patel said it is no longer the case with the third wave of infections.

"We're seeing a lot of young, healthy people end up in the ICU with COVID," he said.

Patel said side effects are also a major concern for those who are hesitant to get vaccinated, particularly the rare blood clots seen with the AstraZeneca vaccine.

However, he noted that getting a blood clot from COVID-19 is "way more" likely than clotting from a vaccine.

"The AstraZeneca risk of blood clots, as we know, especially in the younger women is about one in 250,000. People don't realize that if you just look at blood clots, the risk of a blood clot with COVID is anywhere from 10 to 20 per cent," Patel explained.

Patel said he has diagnosed three people in his ICU this week alone with blood clots from COVID-19.

"It's exceedingly, exceedingly more common with COVID itself than it is with a the vaccine, not to mention any number of other side effects such as long-term muscle weakness, long-term respiratory problems, as well as death even," Patel said.

"So any side-effect that you're looking at with the vaccine is multiple times over with COVID," he added.