Provinces have charted their own paths, but should all adults in Canada have access to second boosters of the COVID-19 vaccine?

Editors Note: Since this article was first published, Canadian provinces have expanded eligibility criteria to varying degrees. Ontario has opened up eligibility, for example, to all adults 18 and over. British Columbia has done the same but with the recommendation that most adults wait until the fall. Alberta’s criteria remains unchanged, but will announce eligibility updates this week. 

Recent polls indicate that the majority of Canadians who have had their third dose are eager to take advantage of the fourth becoming available, though there are signs of a decreased willingness to continue boosting even among vaccinated populations. 

Canadian provinces and territories have gone their own ways on the advisability and availability of fourth COVID-19 vaccine doses, or second boosters.

All are currently offering second boosters to those in long-term care and other congregate living settings. They also have expanded availability to other high-risk populations based on medical conditions, such as those living with certain severe immunodeficiencies.

But eligibility within the general population still varies significantly across the country.

Presently, British Columbia and Nova Scotia are only offering second boosters to adults over 70 years of age and Indigenous adults over 55.

Similarly, Alberta is currently recommending fourth doses to those 70 years and older and Indigenous individuals 65 and older. Labrador is offering fourth boosters to those 70 and above, and Indigenous adults 18 and over.

In Ontario, fourth doses are available to non-Indigenous adults 60 and older and Indigenous individuals 18 and over, the same age requirements as Prince Edward Island.

Manitobans aged 50 and over are eligible for second boosters and Indigenous people over age 30. New Brunswick is also offering fourth doses to those 50 years and older, and Indigenous adults over 18 years old.

Saskatchewan, the Northwest Territories and Yukon are offering boosters to those 50 and above.

Quebec and Nunavut on the other hand, have made second boosters available to all residents 18 years and older as long as their first booster dose was at least three months ago, or 4.5 months ago in Nunavut’s case.

On June 30, the U.S. Food and Drug Administration (FDA) voted to advise manufacturers to add an Omicron BA4 and B5 spike protein component to the current vaccine composition, creating a dual (bivalent) booster. The hope is that the modified bivalent vaccines could be used in early to mid-fall 2022, when another surge is expected.

With this in mind, the National Advisory Committee on Immunization (NACI) recently released its interim guidance for the fall booster vaccination program in Canada.

However, with hundreds of thousands of doses set to expire this month in B.C., Ontario and elsewhere, some are all calling for second boosters to be made available to all who want them.

Experts point to the rise in case counts in Ontario through waste-water testing as indication of a rising summer wave.

So, the question remains: Should the general population (those 18 and over) be eligible for a fourth dose at this time? Or is there greater benefit to be had by waiting? We asked a panel of experts to shed some light on the issue.

The less people hear about the pandemic, the more they can assume everything is fine – it’s not.

Allan Grill, chief of family medicine at Markham Stouffville Hospital

Before we start to talk about fourth doses, I think it’s important to note that third dose vaccination rates in older populations in Ontario have been quite impressive. For 70+, it’s approximately 90 per cent. But a lot of the 18-to-59 group still haven’t gotten their third doses (under 50 per cent). I think that’s an important statistic because this is a three-dose vaccine.

Hospitalization risk is highest for those with less than two doses. If you have two doses, you’re somewhat protected against severe cases and hospitalization. But three doses are even more protective against severe cases and hospitalizations across all age groups. Fourth doses have been available for higher-risk groups for several months now, but the overall uptake has been suboptimal; only 40 per cent of people over age 70 have received a fourth dose. We should continue encouraging this group to get their second booster.

But when it comes to fourth doses for the general population (18-to-59-year-olds), some people are suggesting that since we’ve got an excess supply of vaccines, why don’t we just use them? There probably isn’t much individual harm in giving second boosters to younger populations – any type of severe adverse event is extremely rare.

But it is important to ask the question, what impact will it have on a population level?

We have data from other countries that suggest the actual protection against symptomatic disease with a fourth dose in younger people is short-lived (maybe even less so with the BA5 variant). If they were to boost now, data suggests their antibodies levels would begin to wane by week three. Whereas, in the older (60+) population, this data showed that you actually had an improvement in preventing disease severity with lasting effect.

In Ontario, I think the timing is also key for a few reasons. If cases are going up, getting a fourth dose makes sense because you’re trying to protect as many people as possible during the peak of that wave. I would argue that right now in Ontario we have been seeing a lot more cases, but not to the point where our hospitals are overwhelmed compared to previous waves. People also likely feel more protected in the summer months, as spending time outdoors is associated with less transmission. So even if we did open up fourth doses to younger populations right now, we run the risk of the uptake being only a fraction of what it’s been for third doses. It’s probably better to target them closer to the fall when the impact of COVID-19 will be even higher: When we’ll have competing viruses making people sick and people move indoors.

The timing of the campaign might also be better off later when the new bivalent vaccine may be available that could be more efficacious against the current Omicron variant. Remember, the current vaccine was designed against the original strain of the COVID-19 virus.

There is an opportunity cost here to consider, too. Vaccinating millions of people in a relatively short period of time also takes a lot of resources – particularly human resources within our health-care system that are currently in short supply. Health-care providers are much busier now, as more patients are comfortable being assessed in person, and we are trying to catch up on delayed medical procedures like surgeries and cancer treatments. That’s another reason our ability to launch another mass vaccination campaign may be more advantageous in the fall.

Overall, we need stronger public health communication that this pandemic is not over despite the fact that public health restrictions have been decreased. Vaccination remains a very important piece of this, but so is individual risk reduction in the form of masking indoors, staying home when sick, and using rapid antigen tests to reduce spread to others.

The less people hear about the pandemic, the more they can assume everything is fine. Unfortunately, it is not. We’re still seeing sick patients. We still have staff off sick and a lot of burnout. Anything we can do to continue to chip away at this pandemic and keep case counts down – on top of vaccination – is going to be really important.

The current criteria disproportionately discriminate against women.

Dr. Nili Kaplan-Myrth, family physician in Ottawa

There’s no medical rationale for withholding more COVID-19 doses from people 18 and over across Canada.

We told our patients back in December when we gave them their third doses that boosters would help prevent severe illness, hospitalization and death. Now we know that the protection provided by the vaccine that they got five to six months ago has significantly waned, and COVID is on the rise in our communities.

I was going to hold a vaccine clinic in late June. When I asked public health for the vaccines that will expire in July, I was told I couldn’t have them because the province of Ontario would reprimand public health if we move forward. I asked them if vaccines were then going to go in the garbage and they said they would give them to pharmacies rather than throw them out.

But pharmacies (can’t) distribute vaccines to those under the age of 60, so they can’t use them either. It’s totally bizarre that the government would rather give vaccines to pharmacists then throw them out, rather than to a family doctor who has a community of people who are saying, “Please let me have my booster.”

We’ve dropped our other safety measures so people are vulnerable. Even if they just want to go buy groceries, go into schools, take transit or go to work like I do, seeing patients – they’re surrounded by people who are unmasked. Every encounter with other human beings is putting them at risk, and we have a tool that we’re refusing to use. It doesn’t make any sense.

Some people have asked if we should wait until the next Omicron-specific vaccine is available in the fall. That’s kind of what public health is hinting at as well. But there are two problems with that – one, that vaccine is not specific to BA4 and BA5. And two, by then many of our patients will have gotten COVID again.

The current second booster eligibility doesn’t make sense. In Ontario, people 60 and over are more likely to be retired; to be able to isolate; they’re less likely to be taking care of young children.

The current criteria disproportionately discriminate against women. Who are the caretakers of the children who keep coming home from school and getting sick? Who are the people who are going into long-term care to take care of their loved ones? Nurses, teachers, those most likely to be exposed are all disproportionately women.

From a human rights perspective, why shouldn’t we have equitable access to a vaccine for which there is no medical rationale to prevent us from getting it?

Are you going to vaccinate the entire population with something that may not be useful for more than two or three months?

Horacio Bach, PhD and clinical assistant professor, University of British Columbia’s Division of Infectious Diseases

The data published recently out of Israel shows that the fourth dose is not very effective. We are still using the same vaccine developed against the original strain from Wuhan. We’re at the point where the virus has evolved a lot now and created many mutations and changes in the spike protein, and what’s happening now is that it can evade or escape the immune system faster.

This data showed that the fourth dose against B4/B5 only lasts for one or two months, and that’s it. It means that it’s not beneficial to boost the system for most people, but upgrading it for immunocompromised people or those suffering from chronic diseases is OK.

The FDA published a paper showing that they are now analyzing the data for trials of Pfizer using the Omicron strain sequence as the vaccine and not the original Wuhan strain. That means that now we will start from the latest variant available. The FDA is analyzing the data and will announce whether we need to use a vaccine against the known variant plus the original strain.

We’re also not using any defence strategy to avoid transmission; masking is optional, and public health restrictions are not as strict as in the past. So, the virus is infecting more and more people all the time. Even if it’s not severe, you still give the virus new opportunities to multiply and make new viruses that can pop up anytime in any part of the world.

For me, knowing that this data from Israel shows that the vaccines are not neutralizing the virus as well as they used to and that coverage won’t last as long, the question becomes: Are you going to vaccinate the entire population again with something that may not be useful for more than two or three months?

I would encourage the high-risk population, like immunocompromised people, people in long-term care facilities, those over 60 or 70 years old, let’s say, and those with diseases like diabetes or chronic lung and heart conditions, to get another booster.

It may be an excellent strategy to deal with these populations first. Still, for the healthy or young, it’s like the flu and generally disappears in a few days without causing massive hospitalizations that we’ve seen in the past.

It will be great to have a vaccine against Omicron, but it’s still under evaluation, and we will need access to better long-term data.

It’s tempting to see that as an easy question, but it’s really not.

Lynora Saxinger, infectious diseases specialist with the University of Alberta

It’s tempting to see that as an easy question, but it’s really not. I think the main thing that is missing from the conversation is that we don’t know if frequent boosting – every three to six months or even less than that – is going to be the best long-term strategy to optimize immunity and reduce overall risk. We haven’t had this particular situation on the planet before.

There is some lab-based evidence of possible advantages to having a longer time between boosts. So, what you’re trying to weigh is an unclear longer-term risk of frequent doses affecting long-term immunity, versus the actual risk – at that time for that person in that place – of getting severe COVID-19, when the incremental benefit of a fourth dose over a third dose isn’t necessarily all that large. And that’s a really tough balance.

What should really move the needle on dose four now is true risk. For example, people who have increased risk of infection, like elderly people and transplant recipients, are eligible in most provinces.

Defining the high-risk groups is a bit slippery, but the good thing is that provinces do have internal data on outcomes that they can look at to guide them.

Risk is also related to community spread, and in most places in Canada right now, we’re in this kind of uneasy lull, even if some areas are more active than we’d like. I haven’t looked at the Ontario data recently, and Ontario usually goes faster than we do.

But if we do have a surge, especially with increased hospitalizations, boosting now rather than the fall makes sense. The current vaccine protection against mild infection isn’t great. But protection against severe COVID-19 is good at three doses – and if it is starting to wane, a fourth will still give you a good antibody boost for a while.

But the shape of the pandemic is going to be different in different places, so I don’t think we should consider it important, or even likely, that one single national standard will make sense. Provinces vary in vaccine rollout patterns and have severe waves with different variants so the “community immunity” situation and severity of the next wave may differ.

The basic issue is balancing the booster timing to surges with an expected increase in transmission in the fall. If it was clear that giving shots every three to six months was totally fine, I think that would be an easier choice. But as it is, you’d want to time your best antibody levels for the time of highest risk if things stay stable for the summer.

The other moving piece is, of course, the availability and efficacy of the bivalent vaccine, so timing a “variant” booster in the fall may also have some appeal. But we still don’t know if the next vaccine will be a huge advance or not and when it will be approved.

There’s a lot of advocacy for dose four but a bit of an under-appreciation for the whole question of a possible downside to just giving it to everyone now. Plus, we can’t forget almost half of Canadians haven’t had their extremely important dose three that is keeping people out of hospital.

What I expect is that public health groups across the country will be looking at the local data and trends to weigh risk and benefits and trying to decide when is the right time.

If we want to protect the population, let’s do everything we can.

Steve Flindall, emergency physician in York, Ont.

I’m on the side that thinks we should offer second boosters to the general population. Not only have people had their first booster doses more than six months ago, and immunity starts to wane after about four months, but a lot of people haven’t even had a first booster dose.

It’s no longer a question of access where we had to restrict who could go get a vaccine because we wanted everybody to get vaccinated. Everybody who has wanted a vaccine has gotten one. We have vaccines, and in fact, what I’m hearing is that we’re throwing doses out. The only logic I can see behind withholding vaccines is that it’s a political decision.

There’s no real reason to withhold a vaccine for somebody that wants one. We know the vaccines are safe and effective. So why people wouldn’t offer a disease-preventing vaccine to somebody that wants it is beyond me. I mean, the whole goal of public health is to keep people healthy and prevent disease. If you’ve got an instrument that can do that easily, why not use it?

People’s immune responses are waning from their first booster already. I was boosted eight months ago. I’m four months post optimal response. The question of whether we should wait for a bivalent vaccine or a more Omicron variant specific vaccine – give the people that dose now. Then you can re-boost them later with the more specific one. I don’t see why you can’t do both.

Lastly, I’d say we’re in the start of another wave already. These comments that were made a few months ago about waiting for the fall for dosing are becoming somewhat irrelevant. We didn’t have the BA5 variant coming across the ocean at us then and now it has already landed in our population.

Waiting another three months to dose people when we have an extremely contagious variant that could be as virulent as the Delta variant seems really reckless to me. It’s just another sign of wishful thinking. If we want to protect the population, let’s do everything we can.

I also think we should bring the mask mandates back, especially in health-care settings. It’s not much to ask. Anybody claiming that masking is harmful is just spreading misinformation. If somebody who’s at higher risk of getting severe disease has to go somewhere, I think we should be offering them some societal protection.

The comments section is closed.

  • rickk says:

    Your body your choice – government and public health need to stay out of my arm and stay out of my kid’s arm. With a 99.97% survival if my kid gets covid – I’ll will go with those odds.
    Notwithstanding, we know the current inoculation provides zero protection again omicron. “Experts” need to stop bowing to the new definition of vaccine in that it’s an injection that provides an “immune response” therefore it “works”. And stop with the “but it prevents you from getting real sick from covid” – I guess you have to pitch it somehow to dupe the public to get the 3rd, 4th, 5th shots. Please show us the RCT trails that Pfizer did showing us this ‘not as sick thing’ was one of their end points. Get the smallpox vaccine, you don’t get smallpox and don’t spread smallpox – same for polio. The same cannot be said for the covid inoculation.

    • Linda Wilson says:

      Yes, partically anyine over 50 same as one can get a flu vaccine yearly.


Maddi Dellplain

Digital Editor and Staff Writer

Maddi Dellplain is a national award-nominated journalist specializing in health reporting. Maddi works across multiple mediums with an emphasis on long-form features and audio-based storytelling. Her work has appeared in The Tyee, Megaphone Magazine, J-Source and more.



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