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Fourth doses in Ontario: When should you get one?


Ontario medical experts are continuing to encourage people to get COVID-19 booster shots, but the timing can differ for people who have been previously infected with the virus.

The province has been offering fourth doses – or second boosters – since December 2021. Ontarians who are 60 and older, along with people who are immunocompromised, are currently eligible for a fourth dose of a COVID-19 vaccine.

“In all our vaccines, they usually come in three or fours,” Dr. Dawn Bowdish, Canada Research Chair in Aging and Immunity and a professor at McMaster University, told CTV News Toronto Monday.

“When you had kids and you were taking them to the doctor all the time, three to four doses is what it really takes to cement immune memory – this is not that unusual,” she said.

Bowdish said it’s important to keep up to date with vaccines.


Bowdish recommends people recently previously infected with COVID-19 to wait three months after their infection for their next shot, as antibodies continue circulating in the body.

But those who’ve avoided illness should get it as soon as possible, as Ontario is still in the middle of an Omicron wave, she said.

When four months have passed since the last shot — an infection is more likely.

“Older people and people who are immunocompromised lose that protection a little faster so those are the people we want first in line to get those doses,” Bowdish said.

Getting the booster now she said will not only protect against an infection now, but added by having a less symptomatic infection that’s shorter will also prevent long COVID or other issues that could develop from an illness.


The Ontario government is not currently recommending that children from the ages of five to 11 receive a booster dose.

Right now, the province is recommending that children aged 12 and older receive their booster dose six months after their previous dose and that youth aged 18 and older should receive booster doses three months after their last.

It’s suggested that little ones who have been previously infected with COVID-19 apply the same three-month wait period [post-infection] to get their booster, Dr. Dina Kulik, a pediatrician and founder of Kidcrew, told CTV News Toronto. Otherwise, she recommends sticking to the schedule.

“We want children to get their boosters, adults as well if they haven’t received their boosters,” she said.

Eligible individuals can book an appointment for a fourth dose through the provincial vaccination portal, by calling the Provincial Vaccine Contact Centre at 1-833-943-3900, directly through public health units that use their own booking systems, through Indigenous-led vaccination clinic and at participating pharmacies. Top Stories

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