Is it time for a 4th dose of COVID-19 vaccine? Not just yet

Officially, the numbers are very small.

A total of 18,550 Albertans have received a fourth dose of a COVID-19 vaccine. That's less than half of one per cent of all the doses administered in the province so far.

Presumably, most of those 18,000-plus people were eligible to do so. However, on social media, some who might be ineligible claim to have gotten a fourth dose of either the Pfizer-BioNTech or Moderna vaccines.

Several who had Oxford-AstraZeneca as their first dose and an mRNA vaccine for their second and third shots said their pharmacist agreed to provide a fourth dose due to the time since their last jab, typically five or six months. Others said they asked their pharmacist but were told they were not eligible.

As of right now, Alberta Health says anyone over the age of 12 with an immunocompromised condition is eligible for a fourth dose — no proof required.

"Our data from the fifth wave showed that three doses in other groups continued to provide a high level of protection against severe outcomes," said Dr. Deena Hinshaw on March 23. 

Alberta's chief medical officer of health specifically commented on those who received Oxford-AstraZeneca as their first dose and an mRNA vaccine for their second and third doses, with their last jab more than five months ago.

"Those who got AstraZeneca and then one or more doses of mRNA vaccine more than five months ago are not recommended to have additional doses if they have already had a total of three doses of vaccine," said Hinshaw.

Alberta Health acknowledges those who fall outside current eligibility may have received a fourth shot; however, a spokesperson says the problem is not widespread.

"We are not aware of widespread issues of individuals accessing doses they are not eligible for," said Lisa Glover in an emailed statement.

"However, we discourage Albertans from attempting to receive a fourth dose as it has not been recommended to the general public at this time," she said.

"While it is possible that some people could take advantage of the honour system in isolated cases, we do not believe this warrants placing additional burden on those who are eligible," said Glover.

"Pharmacists are encouraged to follow the policies in place and to administer vaccines based on the current eligibility," she said.

More guidance, more information needed

An infectious diseases specialist at the University of Alberta says it would be helpful to provide more information to people who received Astra-Zeneca first, followed by mRNA vaccines.

"I think the people who got AstraZeneca have had all sorts of communication challenges around, you know, how good is it? How risky, is it, etc, etc. And and I do think that some attention to that would be really useful for them," said Dr. Lynora Saxinger.

Saxinger says people who received two doses of Astra-Zeneca plus an mRNA have very similar protection against severe outcomes as those who received three doses of an mRNA vaccine — and that is part of the message that needs to be spread.

She says there's not enough evidence to suggest a fourth dose is needed for the general population right now.

"There's not been a suggestion that we're going to be running into trouble in a hurry in terms of protection against severe disease."

"I don't think people should feel worried that they're inadequately protected compared to anyone else."

Waiting on the evidence

An associate professor in the department of microbiology, immunology and infectious diseases at the University of Calgary says the push for a fourth dose needs to be based on evidence that immunity from the third shot is waning — and that hasn't happened, even in the face of BA.2, the Omicron subvariant that is now the dominant strain in Alberta.

"That's not to say that they won't be needed down the road. But at this point, we're not seeing that immunity has fallen off significantly after the third dose to justify a broad recommendation for fourth doses for everybody," said Craig Jenne.

Alberta Health says it "continues to monitor the evidence carefully and will listen to the advice of our provincial and national vaccine advisory committees."

"We will continue to make additional dose recommendations as warranted," read the statement.

"What we should take away is that it is being monitored. And when that signal is there, when that evidence is there, and the need is determined, we will see that guidance, just as we did for the third doses," said Jenne.

Saxinger says if a decrease in the protection against more severe infection in specific age groups is detected, then those groups should be first in line for a fourth dose.

Focus on 3rd dose, not 4th

Saxinger says the priority right now should be encouraging Albertans to get their third dose. She says evidence shows people are much better protected against severe outcomes from COVID-19 with three doses rather than two.

In Calgary, the number of adults who have received a third dose ranges from 36 per cent in the upper northeast to 62 per cent in the lower northwest. Provincewide, the number is 46.9 per cent.

"The first step to me is making sure people realize how much work the third dose does against Omicron," she said.

"Two doses still leaves you fairly significantly at risk of a more severe case of COVID, and that risk can really drop if you get your third dose."

Bryan Labby is an enterprise reporter with CBC Calgary. If you have a good story idea or tip, you can reach him at [email protected] or on Twitter at @CBCBryan.