Ontario is now offering second doses of AstraZeneca COVID vaccine. Here’s what you need to know - Toronto Star

Second doses of the AstraZeneca vaccine are back on in Ontario.

A week after the rollout of the British-made shots was paused because of a slight uptick in a rare type of blood clot, senior medical officials announced Friday that, following a review of available data, second doses will be made available to those who want them.

And many Ontarians do want them, officials say.

“If there’s any problem to have, it’s a problem of people wanting something,” said Dr. Dick Huyer, co-ordinator of the provincial outbreak response.

Authorities have spent the past week reviewing the latest data out of the United Kingdom, which suggests the risk of getting a clot is much lower after a second shot than in the period immediately following a first shot.

Given the demand — and the fact that thousands of doses are set to expire — officials now say that if you’ve had a first AstraZeneca dose, you can sign up for a second.

Here’s what we know so far.

So who can one of these second doses?

Ontario is making second doses of AstraZeneca available based on when you got your first.

The first people to become eligible are those who had an initial shot of AstraZeneca between March 10 and 19 — which accounts for between 90,000 and 100,000 people. They will be able to book a second dose for the week of May 24.

At the time of those first doses, AstraZeneca was only being given out in a few areas of the province, so it’s these areas that are going to be initially offering second doses. The public health units getting a small amount of second doses include Toronto, Hamilton, Wellington-Dufferin-Guelph, Peterborough, Simco Muskoka and Peel.

Right now, trucks are gathering up stocks of AstraZeneca and transporting them to those regions so that they’re ready to start going into arms early-to-mid next week, says Justin Bates, CEO of the Ontario Pharmacists Association.

The timing means that these people will get the second shot about 10 weeks after the first dose. While this is slightly sooner than is optimal, Bates says the efficacy is still very good at 10 weeks and this plan will help ensure no doses go to waste.

How do I get one?

People who are eligible should reach out to the pharmacy or primary-care provider where they got their first dose to ask about making an appointment, according to the province. Some of those sites will also start reaching out to people who are eligible.

The government website listing each vaccination site will also be updated, Bates said.

Some large vaccination sites, including Shoppers Drug Mart, will be reaching out to those who are eligible.

Can I wait and get it later?

Bates says the biggest wild card in the rollout has been future vaccine supply, so he still recommends that people get shots as soon as they’re able, but it is your choice.

If you got your vaccine between March 10 and 19, your options are basically to get it next week after 10 weeks; to wait and try to get one at 12 weeks; or to wait and see if the government eventually recommends giving people a second dose of another vaccine, though the research on that isn’t done yet.

What’s this fuss about how far apart the doses are spaced?

As far as Health Canada is concerned, AstraZeneca is authorized to be given anywhere from four to 12 weeks apart. However, unlike Pfizer and Moderna, AstraZeneca is what’s called a viral vector vaccine, and data from the U.K. suggests that for these doses, immunity continues to builds as you go after the first shot.

Waiting for 12 weeks seems to get you the strongest protection, and chief medical officer Dr. David Williams says officials are going to try to make sure that most people get AstraZeneca 12 weeks apart.

That said, there are roughly 45,000 doses in the province that expire at the end of the month that the province doesn’t want to see wasted.

As a result, it is offering doses to some of the first people to get the shot at the 10-week mark, a compromise that balances the need for people to get good protection with the imperative that doses not get thrown out.

Both Bates and Williams say that the efficacy is still very good at the 10-week mark.

Clinical trials looked at a bunch of spacing options, and data suggests that AstraZeneca is about 75 to 80 per cent at 12 weeks, but that likely drops to about 70 to 75 at 10 weeks, Williams said.

“It’s fairly negligible.”

What if I’m not eligible yet?

There will be future announcements for everyone else who is eligible for a second shot of AstraZeneca, the government says.

If top doctors were concerned about safety this time last week, what’s changed?

Ontario paused the use of the AstraZeneca vaccine because the province, which, like every jurisdiction in the country, tracks all adverse reactions from the vaccines, flagged an uptick in a rare type of blood clot called an immune thrombotic thrombocytopenia, or VITT.

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While doctors say it can be treated if caught early, VITT is still serious and can be fatal.

There have now been 21 lab-confirmed cases in Canada, out of just over two million doses administered. In Ontario, the risk of VITT after a first shot of AstraZeneca had been about one in 60,000.

The other significant factor here is that Canada now has enough other vaccines in the country that officials felt they could hit pause on one without derailing the whole vaccination effort.

But in the past week, top doctors have spoken to other jurisdictions, health experts and reviewed the latest data, which suggests the risk of getting a clot after a second dose is significantly lower, said Williams.

Updated numbers from the United Kingdom show the risk there of VITT has been about one in 600,000. This is slightly more than the previous estimate of one in a million, but it’s still very rare, Williams said.

As a result, officials are now “confident” they can offer AstraZeneca is a second dose.

Will everyone who is eligible next week get one?

There is not going to be enough vaccine available if everyone who is eligible tries to make an appointment next week. The province’s current priority is getting doses that will expire out first, and then making announcements about future availability after that.

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Do I have to go to the same location I went for my first dose?

Bates says that’s recommended since it’s easier for record keeping, but all immunization records in Ontario are logged in a central database so you can also go elsewhere and know that the health provider will be able to look up your history.

Can I get Pfizer or Moderna as a second shot instead?

Not yet. Studies about whether or not you can mix and match COVID-19 vaccines are ongoing, including a major one at Oxford University in the United Kingdom.

While early results from that trial suggest it’s not dangerous to get two different vaccines, we don’t get know whether you’d get the same immune response, Williams said.

The National Advisory Committee on Immunization is expected to come out with new guidelines, possibly in early June, federal officials said this week.

Can I get a first shot of AstraZeneca?

At the moment, first shots of AstraZeneca remain paused.

There are exceptions made for people who are allergic to the mRNA vaccines, Huyer said.

How many of our AstraZeneca doses are going to expire?

Ontario currently has about 45,000 doses of AstraZeneca that will expire at the end of May and its these doses that they’re working to move first. Another 10,000 expire at the June.

After that they will start using newer doses that arrived last week, which are good until August.

This file will be updated.

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Ontario is now offering second doses of AstraZeneca COVID vaccine. Here’s what you need to know - Toronto Star
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