The Oxford-AstraZeneca vaccine for Covid-19 was first approved and used in the UK at the beginning of December. Since then it has been used in many more countries.
On February 26, 2021, Health Canada authorized the AstraZeneca COVID-19 vaccine for use in adults 18 years of age and older.
However, on March 1, 2021, the National Advisory Committee on Immunization (NACI) recommended the use of the AstraZeneca vaccine be limited to individuals between the ages of 18 and 64, based on AstraZeneca’s clinical trial data.
On March 16, NACI reviewed more recent real-world effectiveness studies and expanded its recommendation for the use of the AstraZeneca vaccine to people 65 years of age and over.
NACI makes recommendations for the use of vaccines currently or newly approved for use. It is up to each province to tailor their own vaccination rollout plans.
https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci.html
Quebec did not restrict the use of the AstraZeneca vaccine for seniors.
BC approved the use of the AstraZeneca vaccine for workers at risk.
Ontario decided it would not administer the AstraZeneca vaccine to seniors. Instead, it opened up vaccination reservations for people 60-64 who would get the AstraZeneca vaccine. This caused a lot of confusion, resentment and went against its own policy.
Ontario’s policy for the Phase 1 vaccine rollout includes only the following people:
– Congregate living for seniors
– Health care workers
– Adults in First Nations, Métis and Inuit populations
– Adult chronic home care recipients
– Adults over 80 years old
https://covid-19.ontario.ca/ontarios-covid-19-vaccination-plan
The AstraZeneca vaccine should have been allocated to these other groups so that the high risk seniors over 80 years were not bypassed by a younger age group.
This is just another example of bad vaccine management by Ontario. It won’t be the last.
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In the meantime, on March 7, Austria reported two cases of blood clots in people who had received vaccines, one of whom died.
On March 11, Denmark suspended all use of the AstraZeneca vaccine after several cases of blood clots were reported.
By March 16 there were 18 countries in Europe who had suspended the AstraZeneca vaccine, pending an investigation.
All adverse events for any drug, not just vaccines, are reported to a central regulatory agency for review. In the U.S. this is the FDA, in Europe it is the European Medicines Agency (EMA). The regulator then does a thorough investigation and issues an advisory.
The EMA investigated the 25 cases of blood clots that occurred in 25 million people. On March 18, 2021 it issued its report, concluding that “benefits still outweigh the risks despite a possible link to rare blood clots”. https://www.ema.europa.eu/en/news/covid-19-vaccine-astrazeneca-benefits-still-outweigh-risks-despite-possible-link-rare-blood-clots
One of the things that was investigated is the batch of the vaccine to make sure that there was not a fault in the manufacturing of the vaccine. Other factors were investigated and when no causal link was found then the conclusion is that the variation is just a random fluctuation, since people can experience blood clots for many other reasons that are not at all related to the vaccine.
To understand random fluctuation, let’s do some coin tosses. A coin that is balanced and not weighted to any side will come up H (heads) half the time and T (Tails) half the time.
Here are a few sequences.
If you saw this sequence, would you think it was likely?
H T H T H T H T H T H T H T H T H T H T ………… 10/20 Heads, 10/20 Tails
The answer is No. This is a repeating sequence of the exact probabilities, Heads followed by Tails. In a random sequence, it is very unlikely for there to be regular repeating patterns.
There is much more likely to be random patterns, like
H T T H T T T T H H H H T H T T T T T H ………… 8/20 Heads, 12/20 Tails
So how do you determine if 25 blood clots in 25 million people is just a random sequence or if it signifies that there is something systematic, a non-random reason for the variation?
The answer is probability and statistics, a branch of mathematics that has been used for centuries to answer questions like this.
According to such mathematical analysis, 25 blood clots in 25 million people is not significant, in other words it is most likely just normal random fluctuation.
A million is a number that gets bandied around a lot but few people have an intuitive sense of how big this number is. Who has ever counted to 1,000,000 or ever even seen 1,000,000 things with their own eyes.?
Here is a visual picture. The area of the red dot compared to the whole grey area represents roughly 100 out of a million. Computer screen resolution does not allow a smaller dot to represent only 1 out of a million, you would barely be able to see it. This picture is 100 times more than the blood clots that were reported from people who took the AstraZeneca vaccine.
Should you get the AstraZeneca vaccine?
These changing conclusions have led some people to decide that they would not get this vaccine. This is really not a wise decision. All concerns about the AstraZeneca vaccine have been thoroughly investigated by scientific experts in the field. Deciding that the vaccine is not safe when the conclusion by the EMA that the vaccine is safe is an irrational response that ignores all science.
Unless you know for sure that if you turn down an AstraZeneca vaccine you will be able to get one of the other vaccines within a week, you are putting yourself at great risk. With the variants surging, the probability that you could get Covid may be as much as 1 in 500 each week. If you get the AstraZeneca vaccine, which has an efficacy of 76% after the first dose, your risk of getting Covid is not only significantly lower, but your infection would be a lot less severe. And your risk of getting a blood clot from the vaccine is practically 0.
https://www.astrazeneca.com/media-centre/press-releases/2021/covid-19-vaccine-astrazeneca-confirms-protection-against-severe-disease-hospitalisation-and-death-in-the-primary-analysis-of-phase-iii-trials.html
