Following the news of the rare cases of thrombi experienced by some people after receiving AstraZeneca coronavirus vaccines, many questions arise. We have heard about them all our lives, but they are often accompanied by other terms that are sometimes confusing with each other. For example, is a thrombus the same as a clot? What is the difference between thrombosis and embolism? What types of thrombosis are there?
With this article we are going to solve these and other similar questions. But not to panic. Simply to know what they are talking about when we hear or read the above terms in the media.
Thrombi or clots?
When differentiating these two terms, it is important to note that all thrombi are clots, but not all clots are thrombi.
A clot is defined as a mass of blood that has changed from a liquid to a solid state. If this is formed in the inside a blood vessel, we are talking about thrombi.
Coagulation is mainly involved in the platelets and a type of protein called fibrins. Actually, it is an important process to avoid bleeding when we are injured. However, if it gets out of control, due to factors that can range from smoking until the side effects of some drugs, it is more dangerous. It is especially so in the case of thrombi, which can prevent proper blood circulation.
Is a thrombosis the same as a stroke?
In short, when one or more of these thrombi originate in the blood vessels, we are talking about a case of thrombosis. This can be associated with an embolism, but not always, since it occurs when clots circulate with the blood and they travel to a point in the body different from the place where they were formed.
But, going back to thromboses, there are different types, depending on the point at which the thrombi originate and deposit.
What types are there?
In general, there are three types of thrombosis: by precipitation, hyaline and by coagulation.
The first occurs when thrombi originate in arteries or heart, usually due to the detachment of platelets. The second, instead, takes place in veins or capillaries, both due to the detachment of platelets and fibrin. Finally, the latter also occurs in the veins, when a mixture of platelets and fibrin is deposited, with a higher proportion of the latter.
Within these three categories, there are numerous thromboses, which refer to the specific place where the thrombi are found. Some are more common than others, but all agree that, although they may be associated with genetic factors, physical exercise and the abandonment of habits such as smoking or alcohol consumption can help prevent them.
The relationship with AstraZeneca
The two types of thrombosis that have been most detected in people who have received the AstraZeneca coronavirus vaccines have been cerebral sinus thrombosis and the Deep venous thrombosis.
The first is a type of cerebral thrombosis that occurs when thrombi form in the sinuses of the brain. As explained by the Spanish Society of Neurology in a recent statement, it is very rare. In fact, it represents only 0.5% of cerebrovascular diseases that occur in Spain.
It can occur in any age group, but is slightly more common in young women. For this reason, it was initially thought that thromboses of this type originating after vaccination with AstraZeneca could be a simple coincidence, as they occur precisely in the groups in which it is most common. And it is possible that some have been, although we now know that if they are accompanied by low platelets, they may be related to vaccines.
Sinus venous thrombosis headache is worse when the patient lies down and does not improve with standard headache treatments
Its most common symptom is headache that worsens when the patient is lying down or exercising and does not improve with common headache treatments. However, other symptoms may occur, such as focal deficits, sustained loss of strength or sensation, gait or language impairment, confusional episodes, and loss of vision.
Refering to Deep venous thrombosis, also common in severe coronavirus patients, occurs when thrombi form in the deep veins of the body, generally in the lower extremities. That is why it is important to monitor swelling and pain that could be an indicator of leg thrombosis. However, in vaccinated patients with thrombosis and low platelets, thrombi have also been detected in the abdominal area, so their persistent pain in the two weeks after vaccination can be a cause for alert.
Either way, all of this is still rare. The latest EMA resolution has made it clear that the benefits of the Astrazeneca vaccine are more than enough outweighs the risks. We must not fear coronavirus vaccines, but we must be vigilant for possible effects, as with any other drug. That is another of the efforts we need to end this pandemic once and for all.