Windsor Star


Astrazenec­a shot has one in 250,000 risk of clots, but with COVID your risk is higher


For something so momentous, it was actually pretty unremarkab­le.

I filled out a form, rolled up my sleeve, and the pharmacist slipped the needle in. That was it.

I got the Oxford-astrazenec­a COVID-19 vaccine Monday.

I felt like I'd been hit by a truck for about 24 hours. But that was good. It meant my immune system was priming for battle, creating antibodies. And a day on the couch wasn't so bad.

Admittedly, I hesitated before booking the appointmen­t. I wanted the A-list vaccine, the Pfizer-biontech shot, or at least Moderna, both of which appear to offer more protection with fewer reports of rare blood clots. But I had it wrong.

The AZ vaccine is 62 per cent effective, compared to 95 per cent for Pfizer and 94 per cent for Moderna.

But those numbers are deceiving. There's more to it.

The trials for the vaccines were done in different countries at different times. The Pfizer and Moderna vaccines were tested before more contagious and virulent SARS-COV-2 variants were first detected in some countries. The AZ vaccine was tested after the variants emerged. All the vaccines are less effective against some variants.

And an updated peer-reviewed study in the medical journal The Lancet last month showed the AZ vaccine is 76 per cent effective after the first dose. All three vaccines require two doses, and efficacy can also depend on when the second dose is administer­ed. The same study showed that

AZ is 81 per cent effective if the second dose is administer­ed 12 weeks after the first.

Finally, all three vaccines are 100 per cent effective in preventing serious illness and death. That's what counts.

Then there's the blood clot thing.

The risk with AZ is one in 250,000, Dr. Supriya Sharma, Health Canada's chief medical adviser, told the media after Health Canada reviewed the vaccine's safety two weeks ago. But if you haven't been vaccinated, and you end up in hospital with COVID-19, your risk of a blood clot is one in five. That's pretty convincing.

The risk of a blood clot from birth control pills is a lot higher, one in 1,600, Sharma said. I took birth control for 15 years. The risk flitted through my mind maybe once. I was more concerned with not getting pregnant in university or during my freewheeli­ng before-house-and-kids 20s.

If you're pregnant, the risk is one in 300, said Sharma. I had two pregnancie­s. One was twins. If I'd worried about all the risks in a twin pregnancy, I would have gone crazy.

And there are all the flip-flops. People over age 65 shouldn't get the AZ vaccine. Now they should. People under 55 shouldn't. Now, people over 40 can. The data and circumstan­ces evolve, and the recommenda­tions evolve with them. That's the way it should be.

So why was I one of the 54 per cent of Canadians, according to an Angus Reid poll, who was uncomforta­ble with the AZ vaccine?

Maybe I couldn't get the headlines out of my head. Blood clots are scary.

But the pandemic's third wave in Ontario is scarier.

“Our case counts are at an all-time high. Our hospitals are buckling. Younger people are getting sicker. The disease is ripping through whole families.”

That was the latest brief by Ontario's COVID-19 science advisory table. It was the day after my vaccinatio­n. But what it described had been happening for weeks.

Cases are rising in Windsor and Essex County, though not at the same magnitude. But our total number of cases surpassed 15,000 Thursday. About 30 to 50 per cent of our new cases are variants.

What's happening in Toronto can happen here if we don't contain it. And the only way to contain it is vaccinatio­n and public health measures.

Denmark was the first country to drop the AZ vaccine two weeks ago. But its vaccine rollout is advanced, it has enough other vaccines, and the pandemic is under control there.

“If Denmark were in a completely different situation and in the midst of a violent third outbreak and a health-care system under pressure — and if we had not reached such an advanced point in our rollout of the vaccines — then I would not hesitate to use (Astrazenec­a),” the head of the Danish Health Authority told the media.

A lot of medicine is about balancing risk, a doctor once told me. No vaccine, drug or medical procedure is perfect. Measured against everything else, Astrazenec­a's vaccine is good.

I'm not eligible for a shot at a mass vaccinatio­n clinic or from a mobile health team, both of which use Pfizer or Moderna.

The people who are eligible — older people, those with chronic health conditions or from disadvanta­ged neighbourh­oods, essential workers who can't work from home — need it more.

But I'm eligible for a shot at pharmacies, which use the AZ vaccine.

So I did what doctors from local Medical Officer of Health Dr. Wajid Ahmed to Canada's chief public health officer Dr. Theresa Tam are telling us to do. I took the first vaccine available. And I feel lucky I got it.

Windsor Essex County Health Unit CEO Theresa Marentette got the AZ shot. So did Windsor Regional Hospital Chief of Staff Dr. Wassim Saad's mother and Chief Operating Officer Karen Riddell's mother. I figure I'm in good company.

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