Advertisement

NACI recommends mixing AstraZeneca, Pfizer, Moderna COVID-19 vaccines

Click to play video: 'NACI gives green light to mix-and-match COVID-19 vaccines' NACI gives green light to mix-and-match COVID-19 vaccines
WATCH: Canada’s National Advisory Committee on Immunization (NACI) updated its guidance on Tuesday, recommending that certain approved COVID-19 vaccines can be mixed and matched. Global News Health Reporter Jamie Mauracher has more on the safety of taking two different doses – Jun 1, 2021

Canada’s National Advisory Committee on Immunization (NACI) has updated its guidance, recommending that approved COVID-19 vaccines can be safely mixed and matched in most scenarios.

Under the new recommendations released June 1, people who received a first dose of the AstraZeneca vaccine may receive an mRNA vaccine — Pfizer-BioNTech or Moderna — for their second dose, unless contraindicated.

But it is not recommending AstraZeneca after a first shot of Pfizer or Moderna because of safety concerns and limited data on the use of this combination.

Read more: 2nd COVID-19 shots should be offered ‘as soon as possible’: NACI

People who have received a first dose of an mRNA vaccine should be offered the same vaccine for their second dose, NACI said. But mRNA vaccines can be interchangeable if the same product is not readily available for the second dose, it added.

Story continues below advertisement

In either case, the previous dose should be counted, and the series need not be restarted, the guidance stated.

Click to play video: 'Advice on mixing vaccine shots based on goal of not wanting vaccine doses to go to waste' Advice on mixing vaccine shots based on goal of not wanting vaccine doses to go to waste
Advice on mixing vaccine shots based on goal of not wanting vaccine doses to go to waste – Jun 1, 2021

The non-binding recommendations were based on a range of factors — from safety concerns to vaccine supply, Theresa Tam, Canada’s chief public health officer, said during a news conference Tuesday.

“The interchangeability of vaccines means that you can receive one vaccine product for your first dose and then safely receive a different vaccine for your second dose to complete your two-dose vaccine series for optimal protection from COVID-19,” Tam said.

“This advice provides provinces and territories with effective options to manage their vaccine programs,” she added.

Click to play video: 'Will B.C.’mix and match’ COVID-19 vaccines?' Will B.C.’mix and match’ COVID-19 vaccines?
Will B.C.’mix and match’ COVID-19 vaccines? – May 31, 2021

Early data from studies in Europe suggests that mixing doses of COVID-19 vaccines is safe and effective.

Story continues below advertisement

Preliminary results from a University of Oxford study published on May 12 found that mixing the Pfizer-BioNtech and AstraZeneca COVID-19 vaccines may increase the frequency of mild to moderate side effects. But these symptoms were short-lived — lasting no longer than a few days — and there were no hospitalizations or other safety concerns.

Read more: Mixing COVID-19 vaccines appears safe — but no data on whether it works, U.K. study says

Meanwhile, a Spanish study released on May 18 showed that the presence of neutralizing antibodies rose sevenfold after people who already received a first shot of AstraZeneca vaccine were given the Pfizer dose, significantly more than the doubling effect observed after a second AstraZeneca shot.

A nationwide study was also launched in Canada last month to look at the safety and effectiveness of mixing and matching different types of shots.

Click to play video: 'Albertans being sought for national study on mixing COVID-19 vaccines' Albertans being sought for national study on mixing COVID-19 vaccines
Albertans being sought for national study on mixing COVID-19 vaccines – May 20, 2021

Amid concerns of reports of rare blood clots linked with the AstraZeneca vaccine, NACI said several European countries had begun offering an mRNA vaccine as the second dose to those who received a first shot of AstraZeneca.

Story continues below advertisement

The risk of the new blood-clotting syndrome, known as vaccine-induced thrombotic thrombocytopenia, or VITT, was among the considerations for NACI’s updated guidance.

“This is not a new concept,” the Public Health Agency of Canada (PHAC) said in a statement.

“Similar vaccines from different manufacturers are used when vaccine supply or public health programs change.”

Read more: ‘No A, B list of COVID vaccines’: Experts weigh in on NACI’s ‘mixed messages’

Tania Watts, an immunologist and professor at the University of Toronto, said NACI’s new recommendation was “great news,” making it easier to get the second dose into people’s arms.

While NACI makes recommendations for the use of vaccines approved for use by Health Canada, it is ultimately up to the provinces and territories to implement that advice.

Click to play video: 'The National advisory Committee on immunization changes to vaccine mixing and matching' The National advisory Committee on immunization changes to vaccine mixing and matching
The National advisory Committee on immunization changes to vaccine mixing and matching – Jun 1, 2021

Some experts fear that this could lead to wastage of Canada’s AstraZeneca supply.

Story continues below advertisement

“It may now be more challenging to get a second dose of the AstraZeneca vaccine into people who remain overly concerned about side effects, despite the fact that VITT, which is quite uncommon, is even less common amongst second-dose recipients,” said Gerald Evans, an infectious disease specialist at Queen’s University in Kingston, Ont.

Click to play video: 'Study shows COVID-19 vaccine mixing produces ‘robust immune response’: Dr. Tam' Study shows COVID-19 vaccine mixing produces ‘robust immune response’: Dr. Tam
Study shows COVID-19 vaccine mixing produces ‘robust immune response’: Dr. Tam – Jun 1, 2021

Tam said it remains to be seen what the actual uptake of AstraZeneca will be following the new guidance.

“We don’t want to be ordering vaccines if we’re not using it, but it can only be ascertained in a more granular way when we see what the vaccine uptake looks like in the coming days,” she said.

— With files from Global News’ Abigail Bimman 

Sponsored content