Why did Canada ‘switch up the script’ on second doses of the AstraZeneca vaccine? Here’s what we know

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This article was published 16/06/2021 (1246 days ago), so information in it may no longer be current.

In the latest speed bump for what has been dubbed ‘Generation AZ,’ a national advisory council is recommending those who got AstraZeneca for their first vaccine dose switch teams to Pfizer or Moderna for their second.

The new guidelines were prompted by emerging evidence from Germany that suggests mixing doses might spark a stronger defence from your immune system, the National Advisory Committee on Immunization said Thursday.

It’s also a decision likely spurred on by the rapid spread of the Delta variant, which could be the most transmissible version of the virus Canada has seen yet.

Still, the decision has raised questions about the fate of more than half a million doses still unused, not to mention future shipments, and kicked up even more confusion for those people, many of them Gen Xers, who turned out in droves in recent months to roll up their sleeves for a vaccine that is no longer being recommended and has also since been linked to side effects that are very rare.

NACI also updated its previous recommendation to say that everyone should always get the mRNA vaccines first, unless they are allergic to them.

Daniela Battistella’s first reaction was simple: “what the f-k?”

When the pharmacy where she got her first shot called up and told her a second shot of AstraZeneca was available, she jumped at the chance to get fully vaccinated — and the chance to make sure a good vaccine dose wasn’t going to expire.

“We are thinking we are doing the right thing, following advice, and then they switch up the script,” she said. Now, Battistella, who lives in the Waterloo region, one of 10 Delta variant hot spots in Ontario, worries about how protected she is against the Delta variant and hopes more information becomes available soon about whether she’ll still need a shot of an mRNA vaccine in the future.

Health experts push back against the idea that anyone should have buyer’s remorse over getting the AstraZeneca vaccine, which remains a very effective shot.

But, as Dr. Peter Jüni, head of Ontario’s COVID-19 science advisory table, points out, the latest virus variant is poised to reshape the landscape once again.

“The point is now we have a situation where we have the new Delta variant, and based on the data we have, it is very likely that the second dose being an mRNA vaccine will be more effective than a second dose of AstraZeneca,” he says.

Both Pfizer and Moderna use a technology based on mRNA and are, in practice, very similar vaccines, Jüni says.

The other factor here is that while the risk of a blood clot, known as a vaccine-induced thrombotic thrombocytopenia, or VITT, is small with AstraZeneca, it isn’t zero. With large shipments of mRNA vaccines expected in the coming weeks, Canada is in the “lucky” position of being able to use them first, he adds.

While he wouldn’t recommend that any of his patients get a second AstraZeneca shot if Pfizer or Moderna was available, he says he’d have “no problem” with someone choosing it for themselves.

“Based on the data we have, it is very likely that the second dose being an mRNA vaccine will be more effective than a second dose of AstraZeneca.”–Dr. Peter Jüni

If someone was well informed about the risks and the benefits of getting a second AstraZeneca shot, “who am I to suggest they shouldn’t do that?”

This is unlikely to be the final word on mixing vaccines, says Dr. Lynora Saxinger, an infectious disease specialist, based out of the University of Alberta.

While there is now limited data out of Europe that suggest mixing doses could offer better protection against the variant, the world has been waiting on a full trial that has been underway at Oxford University in the United Kingdom for months.

While researchers released an early look at data that found mixing shots is safe, albeit with a slight increase in side effects, the full report on how well it works isn’t known.

But, with Delta looming and more people needing to make a decision about their second dose, NACI likely felt some pressure to make a decision sooner, Saxinger says.

“This is looking like it’s going to be the right thing to do. But, as always, we should reserve our right to learn, and to change courses as we need to.”

Meanwhile, those who got AstraZeneca as a first shot, and who have already weathered shifting advice, changing age requirements and even the news that their vaccine certificates won’t be accepted on Broadway, are left to weigh wait times against the possible benefit of an mRNA second dose.

“Choice is good when choosing consumer electronics. I find this level of choice unhelpful, I’m no expert,” said Mark Malowany in Alberta.

Toronto lawyer Derek Ground was just half an hour from his second dose AstraZeneca appointment when he heard about the NACI update.

“I’m thinking, ‘What the hell do I do?’ ” he said. And then he thought of all the crap he’d put into his body over the years. “Why am I worrying? I smoked cigars for 40 years.”

“Choice is good when choosing consumer electronics. I find this level of choice unhelpful, I’m no expert.”–Mark Malowany

He opted to keep his appointment, and, speaking to the Star afterwards, said: “I wanted to get it done and I wanted to get it done for the right reasons. But I have to tell you a small part of me feels a bit duped. And this could end up in my no-good-deed-goes-unpunished file.”

He also wonders what will happen to doses of AstraZeneca that go unused, and whether they will be given to other countries in dire need.

Canada has advance purchase agreements that entitle it to a total of 22 million doses of the vaccine between the ones that come straight from AstraZeneca and the Covishield version made in India. Roughly three million have arrived in the country so far, of which some 600,000 doses are sitting in freezers.

It’s not yet clear what will happen to them, or to the shipment of an additional one million doses that officials said last week were scheduled to arrive at the end of the month.

But for Rhys Albrecht in B.C., who was vaccinated with his second shot of AstraZeneca on Monday, the first appointment for a second dose available to him, what matters most is that he will soon be even more protected against COVID-19. He had decided to get the first shot he could; he still remembers getting his first appointment back in April felt like winning the lottery.

“I feel very fortunate that I was able to get the second shot,” he said. “I did not think it was going to happen this quickly.”

Alex Boyd is a Calgary-based reporter for the Star. Follow her on Twitter: @alex_n_boyda