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Ontario is now allowing all adults to book fourth doses of a COVID-19 vaccine but the province's top doctor has said healthy young adults can choose to wait until the fall for a new shot that's expected to target Omicron subvariants. The Canadian Press asked experts what individuals should consider as they weigh whether to get a fourth shot this summer. 

What questions should people ask themselves when deciding whether to get a fourth shot? 

Dr. Susy Hota, medical director of infection prevention and control at the University Health Network in Toronto, said individuals should assess whether there's a lot of COVID-19 activity in their community. If there is, Hota said they should consider getting a fourth dose sooner than later. 

Another factor to weigh is whether individuals are more at risk of having a severe case of the virus if they contract it — or if someone in their household is, she said. That includes people with underlying health conditions like heart disease and chronic lung disease. 

"That's really where we want to make sure that any waning immunity has been addressed by a booster dose now, because COVID is increasing across the country," Hota said. 

Dr. Kashif Pirzada, an emergency room doctor in Toronto, said people should check when they got their last vaccine – if it's been six months or more, they would benefit from getting another jab now.  

"Antibody protection wanes over time, especially four or five months after your vaccine and (vaccines) can protect you from developing infection in the first place and also prevent onset of severe disease," he said. 

What questions should residents ask their doctors?

Hota said people can review their health history with their health-care providers and also have a conversation about who they live with and whether those individuals are at high-risk of severe outcomes. 

Pirzada said there's "division in medical opinion" because some health-care providers want to wait for more evidence before making recommendations. 

"But the problem is, as things are developing with the pandemic, stuff happens a lot faster than the studies that follow do," he said. 

The province's top doctor advised Ontarians to consult their health-care providers on whether a fourth dose now is right for them.

What should people keep in mind when it comes to a new shot targeting Omicron variants expected for the fall? 

Chief Medical Officer of Health Dr. Kieran Moore has said a new vaccine is expected in the coming months and the province will likely start vaccinating high-risk indviduals with it earlier in the fall. That means most Ontarians likely wouldn't be eligible for the new shot until closer to November or December, he said. 

Pirzada said Ontarians should consider that timeline. 

"The Omicron boosters won't be available for most people until I would say October, November, the way things are going," he said. "So if you get it now, you'll be in perfect form to get another booster in the fall."

Raywat Deonandan, an epidemiologist and associate professor in the Faculty of Health Sciences at the University of Ottawa, also said the timeline was important to keep in mind. 

"Do you have faith in your government to acquire sufficient doses in the fall of this high-in-demand Omicron booster? Do you expect that come the fall, the dominant variant circulating will be the same dominant variant circulating today?" he said. 

What are the benefits of getting a fourth dose now and are there any downsides?

It's "perfectly safe" to get a booster now and then get the Omicron-specific booster after a few months "because there'll be quite a time lag between the two," Pirzada said.  

Evidence from third doses has shown that vaccines are "very helpful" at reducing the severity of the virus, hospitalizations and the risk of developing long COVID, he said.  

Getting a fourth dose now will help not just individuals, but the entire province with navigating the seventh wave, Hota said. 

"Our goals are to protect people and to preserve the healthcare system, so getting your fourth dose can help with the current wave that's already underway, to be smoother for us to deal with," she said. 

Deonandan said it's clear that "the fourth dose of the current formulation is actually pretty good,"pointing to studies from Israel and the U.S. that found four doses are more protective against symptomatic disease, hospitalizations and death than three doses. 

For young, healthy adults, Deonandan said getting a fourth dose now will help protect them from getting COVID-19 and spreading it to others that are at higher risk. 

"To me, the answer is obvious – you get it now," he said.

This report by The Canadian Press was first published July 14, 2022.

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This story was produced with the financial assistance of the Meta and Canadian Press News Fellowship.

Noushin Ziafati and Holly McKenzie-Sutter, The Canadian Press