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May. 8, 2021 | Saturday
Editorials and Opinions
Letter: Vaccine still much safer than contracting COVID

Dear editor:

There has been a lot of information published about the possibility of blood clots in persons taking the AstraZeneca vaccine. As the science behind vaccine use is moving rapidly so is the guidance provided to health care providers.

The AstraZeneca (AZ) vaccine was studied in 34,500 patients on vaccine and over 20,000 patients in the placebo group. There was no increased risk of blood clots in the body in the population receiving the AZ vaccine compared to those on placebo. This was a sufficiently large enough trial size to discern a difference in blood clots in the body.

If, however, a blood clot which occurs in the brain at a rate of 1 in 125,000 to 1 in 1 million people, the trial would not pick up the difference. This is the reason why all modern health authorities such as Health Canada have instituted a post-marketing surveillance program to monitor potential side effects as they occur.

A recent study from Germany found an association between the AZ vaccine and blood clots in the brain: they called this Vaccine Induced Prothrombotic Induced Thrombosis (VIPIT). This blood clot in the brain would occur four to 16 days after vaccine administration.

The person could develop many symptoms, such as persistent headache, blurred vision, seizures and also possibly chest pains with difficulty breathing or pain the legs or arms with swelling. These clots occurred predominantly in younger women under the age of 55. These clots resemble the clots seen in heparin-induced thrombocytopenia, which is a treatable condition.

This report is what led the Canadian National Advisory Committee on Immunizations (NACI) to advise the various public health units in Canada on March 29 to recommend with an abundance of caution to limit administration of the AZ vaccine to people over the age of 55. They outlined the information regarding VIPIT and the AZ vaccine.

On April 2, the Ontario COVID-19 science advisory table, which advises physicians on how to treat patients with COVID in Ontario, published a guidance for emergency room physicians on what to do in case of suspected brain blood clots with the AZ vaccine. The guidance was specific for blood clots in the brain (VIPIT). There are four approved drugs that can be used to treat this condition. 

There have been over 700,000 AZ vaccines doses administered in Canada and so far only one case of VIPIT has been reported. More importantly, physicians have been warned of this potential risk as well as how to treat it. No brain clots were seen in over 20 million doses of AZ vaccine in persons over 55 years old globally. We are now starting to inoculate the over 60s in Ontario and while VIPIT cases are rare, if they occur, ER physicians have now been advised on how to treat and manage them.

Most importantly the new virus variants are faster to infect and can result in more serious consequences. We are in a third wave in Ontario with a case increase of 30 per cent. The new variants are becoming the dominant virus. The AZ vaccine has been shown to be effective at preventing hospitalization with the B.1.1.7 or U.K. variant.

It is estimated that if you become infected with COVID-19, the virus has a risk of blood clots of 1 in 100 in non-hospitalized patients and 1 in 20 in those in hospital. These blood clots can have devastating effects in the long term as well as potentially lead to the need to use blood thinners for prolonged periods of time after they have dissipated.

This is the reason why Health Canada, the NACI and the science table continue to advise that the benefits of the AZ vaccine still outweigh the risks. More importantly these scientific bodies are taking all the possible precautions to protect the population being vaccinated. You should find comfort in that and trust that they are acting in your best interest.

On Tuesday, April 13, Johnson & Johnson vaccine use was paused in the U.S. after it was reported that 1 in a million women in the 18 to 48 age group developed blood clots in the brain, six to 13 days after they received the vaccine. The mechanism seems to be the same as the clots with the AZ vaccine. The Johnson & Johnson vaccine is not yet in use in Canada.

Robin Jinchereau