Frequently asked questions about blood clots, safety, risks, and symptoms


The rare but serious blood clots that have been linked to the AstraZeneca COVID-19 vaccine have many people, especially those who have already had a dose of vaccine, looking for information. Here are answers to some key questions.

If I had a first dose of the AstraZeneca COVID-19 vaccine, should I worry about safety?

Whenever there is a risk, you should always be aware and informed. There is a risk of very serious damage, including death, although it is very low: approx. one in 55,000 for the first dose.

We now have a much better understanding of how to diagnose and treat coagulation due to COVID-19 vaccines, called vaccine-induced thrombotic thrombocytopenia, or VITT (also sometimes called vaccine-induced prothrombotic immune thrombocytopenia, or VIPIT) when it occurs. . Mortality rates among people experiencing VITTs have been estimated at between 20 and 50%, but it may improve as knowledge increases. The Public Health Agency of Canada controls all adverse events after vaccination against COVID-19.

It is important that everyone who has had the AstraZeneca vaccine understands that it was the right one. It is an excellent and effective vaccine, and vaccination is an important act to protect not only yourself but your community by slowing down and ultimately stopping the pandemic.

Should I receive a second dose of AstraZeneca? If so, when?

Getting the second dose of any vaccine in two steps is very important. This is what cements the memory of the immune response. We know that clinical trials that the first dose does not prevent all infections. Prevents death from infection. The second dose increases the immune response to protect yourself almost completely from any infection. This second dose also greatly reduces your ability to carry or spread the virus.

As for the weather, there is still evidence, but the best guidance on AstraZeneca is that 12 to 20 weeks difference between first and second dose it is ideal, as with most vaccines.

Are the risks different for a second dose?

The risk of a blood clot after a second dose it is approximately one in every 600,000, which accounts for one-tenth of the risk of clotting after an initial dose. If you feel comfortable taking the first dose, you should feel good to move on and continue to help the community bring the pandemic to an end. In addition, knowing the symptoms associated with vaccine-related clots allows for timely recognition and immediate treatment.

What are the health risks of blood clots that can follow a vaccine?

In those very rare cases where blood clots follow vaccination, they can be very serious and can be fatal. Best of all, knowledge is advancing rapidly, especially when it comes to diagnosing and treating these clots when they occur.

At the beginning of the vaccine launch, the risk of death in the rare cases of coagulation was 60 to 80%. Today it is 20%.

At the start of the release, patients had no way of knowing what a vaccine-related clot was or what to look for. It may have been a key factor in the higher mortality rate. Now that this problem is known and symptoms can be identified, the risk of death is much lower. As we have progressed in understanding how this problem presents itself, people are diagnosed and treated much sooner and more effectively.

Is it safe to get a different vaccine for my second dose?

From Canada National Advisory Committee on Vaccination recommends that, for a second dose, you stay with a vaccine made with it technology platform”Like the first one. If you first received AstraZeneca, which is a form of viral vaccine, it is recommended that you take it again. If not available, Johnson and Johnson are another viral virus vaccine.

If you have had a vaccine based on an mRNA technology platform (Pfizer or Moderna), you can have one of these two for your second dose. More data is emerging and it can ultimately be shown that mixing and blending platforms are safe and effective, but for now, the recommendation is to stay with the same technology.

Are there symptoms that people should be on the lookout for that could indicate a blood clot?

He VITT symptoms they are well documented and include the following, which occur four or more days after vaccination:

  • Severe and persistent headaches.
  • Severe and persistent blurred vision.
  • Swelling of the legs.
  • Difficulty breathing.
  • A stomachache.
  • Contusions beyond the vaccination site.

It is important to seek prompt medical attention in these cases. It is also important to keep this in mind minor fever, headache, fatigue and pain at the site of vaccination they are common with all vaccines for the first or two days and are not a cause for concern.

Who is at risk of clotting related to the AstraZeneca vaccine?

Coagulation events are still so rare that it is very difficult to identify any particular risk factor. Although it seems that a a slightly higher number of women have experienced coagulation, the number of cases is not large enough to accurately assess whether sex may affect risk.

The AstraZeneca vaccine is not recommended for people who have had a previous case heparin-induced thrombocytopenia, or rare clots of cerebral venous sinus thrombosis. Family history of coagulation does not appear to be relevant to the risk of vaccination, as the mechanisms are completely different.

Dawn ME Bowdish, Canada Research Chair in Aging and Immunity, McMaster University i Ishac Nazy, Associate Professor of Medicine and Scientific Director of the McMaster Platelet Immunology Laboratory, McMaster University

This article is republished from The conversation under a Creative Commons license. Read the original article.

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