Two vaccines – the Johnson & Johnson vaccine within the U.S. and the AstraZeneca vaccine in Europe – have been linked to an elevated probability of a uncommon kind of blood clot. Researchers are investigating what causes these clots and are beginning to suggest some solutions. Dr. Mousumi Som, a professor of drugs at Oklahoma State College, explains what these uncommon clots are and the way they’re forming after individuals get vaccinated.
1. What are the blood clots?
A small variety of individuals within the U.S. have developed harmful blood clots after receiving the Johnson & Johnson vaccine. The clots have principally been occurring in individuals’s brains and, paradoxically, are related to low platelet counts.
Usually, platelets assist an individual cease bleeding after they get injured. Should you get a minimize or have an harm, the physique responds by sending platelets which act as a brief patch. The patch attracts different platelets and so they stick collectively to cease blood loss. Since platelets usually assist the clotting course of, this mix of low platelets and excessive clotting makes these clots medically uncommon.
These particular kinds of clots – referred to as cerebral venous sinus thrombosis – though uncommon, have an effect on round two to 5 individuals per million per 12 months and are probably life-threatening with out remedy. Vaccines aren’t usually a set off for this sort of clot.
2. Who’s having these clots?
As of April 24, 2021, out of the 8 million individuals vaccinated with the Johnson & Johnson vaccine within the U.S., about 16 individuals have developed these blood clots. The clots occurred from six to 13 days after immunization, and the bulk had been in ladies between the ages of 18 and 48.
On April 26, 2021, information studies indicated that at the very least one man had developed a clot. The person is in his 30s and was hospitalized from a clot in his leg about two weeks after receiving the Johnson & Johnson vaccine.
Well being officers in Europe have additionally reported that the AstraZeneca vaccine – a COVID-19 vaccine approved and permitted in Europe however not within the U.S. – has brought about about 200 instances of low-platelet clotting. Importantly, each the Johnson & Johnson vaccine and the AstraZeneca vaccine use a sort of innocent virus referred to as an adenovirus to ship directions to the human physique on how you can construct an immune response to COVID-19. That is referred to as a viral vector vaccine.
The truth that the each vaccines use a viral vector and each are related to blood clots has led many well being consultants to suppose that the clotting problems with the 2 vaccines might share the identical mechanism.
3. Why are ladies getting extra clots than males?
At this level, docs nonetheless don’t know what makes ladies extra prone than males, nor what places an individual in danger for these clots. These clots can happen, although hardly ever, in individuals who don’t get a vaccine. Scientists know that girls are thrice extra prone to develop such a clot with out receiving the vaccine. Many researchers suppose that is due to contraception or different hormonal replacements that girls take.
4. Why would possibly the vaccines be inflicting blood clots?
Researchers imagine that this particular low-platelet clotting is much like a response some people get after they obtain a blood thinner referred to as heparin, referred to as heparin-induced thrombocytopenia.
Docs typically use heparin to skinny an individual’s blood within the case of a coronary heart assault or a blood clot when blood circulate must be reestablished. However some individuals expertise the alternative response, and their blood finally ends up clotting extra as a substitute. This occurs as a result of the physique triggers an undesirable immune response after receiving heparin.
In these sufferers, heparin attaches to a product launched from platelets referred to as platelet issue 4. When this occurs, the immune system considers the mixed platelet issue 4 and heparin an issue, so it creates antibodies in response. These antibodies connect to the heparin and platelet issue 4 advanced, and the physique – which now thinks it must restore an harm – causes extra clotting whereas utilizing up much more platelets. This ends in the low platelet depend seen in these sufferers.
When docs have regarded on the blood of sufferers who developed clots after receiving the Johnson & Johnson or AstraZeneca vaccine, it regarded similar to the blood of people that have the low-platelet clotting response to heparin. This has led scientists and docs to imagine that the identical course of could be main to those clots brought on by the 2 vaccines.
This text is republished from The Dialog, a nonprofit information web site devoted to sharing concepts from tutorial consultants. It was written by: Mousumi Som, Oklahoma State College.
Mousumi Som works fr the Oklahoma State College Heart for Well being Sciences. She has obtained funding from Eli Lilly and NIAID for drug associated analysis on COVID therapies. She is affiliated with the Nationwide Board of Osteopathic Medical Examiners and the Osteopathic Founders Basis. .