The thrombi by AstraZeneca they have become the star topic in recent weeks. While scientists study what happened, to check whether or not there really is a relationship between the two phenomena, social media experts give their verdicts, with a little less research behind it, and the media put their two cents to hysteria collective with often misleading headlines. The coronavirus vaccines they already caused certain fears to the population for having obtained so quickly. Now, there is a tangible reason to fear them, or so it seems.
However, the European Medicines Agency (EMA) insists that, if the relationship really exists, it would be an extremely rare side effect and that, furthermore, the benefits outweigh the risks.
This is something important. As an example, the thrombi themselves serve. Suddenly the possibility of thrombosis caused by the AstraZeneca vaccine makes a world for us. But we forget that the coronavirus itself can also cause blood clots, among many other complications. And it is not a suspicion. It is something very researched, about which numerous studies have been written this year.
One of the few thrombotic viruses
Few are known to this day viruses that cause thrombi. Some are known cytomegalovirus can cause thrombosis and that the virus varicella zoster it is capable of causing both blood clots and hemorrhages.
Additionally, the two most remembered relatives of SARS-CoV-2, SARS-CoV-1 and MERS-CoV, have also been found to cause them.
Therefore, it was not surprising to see that this new coronavirus also did it. It was initially verified in the autopsies of some deceased, in which they were found microthrombi in the pulmonary vasculature. But later, cases of thrombosis in patients who had managed to overcome the disease. This can happen during the days of admission, especially if they have been in the ICU, of course. However, some studies have shown that patients admitted for COVID-19 show a greater propensity to develop thrombosis than those who were hospitalized for other pathologies. And also more than with coronavirus vaccines.
Thrombi Not Caused by Coronavirus Vaccines
One of the tests used to analyze whether a person has thrombi is the D-dimer. It is a test aimed at analyzing the presence in the blood of a protein associated with the dissolution of clots.
For this reason, most studies on thrombi associated with the coronavirus started from performing this test at patients previously diagnosed with COVID-19.
As an example, a study by Chinese scientists in April 2020 pointed to abnormal levels of this dimer in a 43.2% of mild patients of coronavirus and in a 59.6% of the bass.
This indicates a problem in the coagulation. In fact, it is consistent with the results of another study, which indicates that approximately half of seriously ill patients develop coagulopathies. Although they are not all the same.
Pregnant women and diabetics seem more likely to develop thrombi due to coronavirus
For example, a review published in July 2020 by scientists from India, Ukraine and the United Kingdom, showed that the 15% of COVID-19 patients with pneumonia and elevated D-dimer developed Deep venous thrombosis. According to the Mayo Clinic, this is what occurs when clots develop in one or more deep veins in the body, mainly in the legs. It is, for example, one of the coagulopathies that are being studied in people who have received coronavirus vaccines. This same study finds that it is even more likely in patients with previous pathologies, such as diabetes.
An increased likelihood of thrombosis has also been observed in pregnant with coronavirus. For example, in a study conducted with 20 pregnant women with COVID-19, it was found that 10 of them developed poor fetal vascular perfusion or fetal vascular thrombosis.
Problems in the ICU
The same study from July 2020 shows that more than 20% of patients admitted to ICU due to coronavirus they end up developing thromboembolism. It is logical, after being intubated or spending a lot of time in bed. However, the same study indicates a proportion of thromboembolisms less than 2% in patients admitted to intensive care for other pathologies.
Even so, it should be noted that these data contradict those of other studies that do not find large differences between COVID and non-COVID ICU patients.
Cytokine storm, responsible for severe cases in young people, seems to be related to thrombi
What is clear is that hospitalization, especially in intensive care, it is a risk factor for the development of thrombi. But it’s not the only motive. In reality, it seems that the coronavirus itself generates processes in the body that lead to a uncontrolled clotting.
Its own mechanism of entry into cells causes increased action of hormones angiotensin II vasoconstrictor and the decrease in vasodilators. Furthermore, the phenomenon known as cytokine storm, responsible for many of the severe cases of COVID-19, including in young patients, gives rise to a very intense inflammatory process, which can also trigger the formation of thrombi.
Thrombi and coronavirus vaccines
The United Kingdom has detected 30 blood clots among 18 million people who received the coronavirus vaccines with AstraZeneca. Germany, 31 cases of thrombi among 2.1 million vaccinated people.
This yields very different percentages, which could be explained by different reasons. On the one hand, they do not have nothing to do with the vaccine. On the other, that there is a certain genetic predisposition. The latter is something that can be linked to geographic region. Either way, in both cases the percentage is very low. Millions of people who could have become seriously ill and developed blood clots have not done so thanks to coronavirus vaccines.
Logically, comparing thrombosis percentages for one reason or another does not make sense, since they are not done studies under the same conditions. These are not data that can be extrapolated, but they help us to get the idea that, among other symptoms, those vaccines that we fear so much can also protect us from thrombosis. And perhaps not to us, but to that diabetic neighbor who has not yet been vaccinated, to that pregnant friend who has been recommended not to get vaccinated until giving birth or to that immunocompromised grandfather who has not been able to vaccinate due to the weakness of your immune system.
That is why the EMA talks about the benefits outweigh the risks. Our benefits and those of the people we love.