What do you do if you think you have VITT? What do we know about rare clotting disorder

A new blood-clotting syndrome seen in a small minority of COVID-19 vaccine recipients continues to attract significant attention, but in most cases experts maintain the phenomenon to be very rare – and treatable.

Vaccine-induced thrombotic thrombocytopenia, or VITT, has been identified in a handful of Oxford-AstraZeneca recipients in Canada, leading to the death of a patient.

Executive Director of Thrombosis and Atherosclerosis Research Institute (TAARI) at McMaster University, Drs. Jeff Weitz says doctors are learning more about VITT every day.

And this is good news for people concerned about developing the disorder.

“Now we know how to diagnose it and we know how to treat it,” Weitz said. “So even if you are one of those unfortunate, rare individuals – maybe four out of a million – who get it, we know what we have to do.”

While experts maintain the benefits of vaccination to overcome the small risk of clotting, Weitz noted that clots are more frequently detected in COVID-19 patients.

Here we know about VITT:

how does this work?

The risk of VITT is estimated to be anywhere in one case out of 250,000 at a dose of 50,000.

Thrombosis specialist Drs. Maneka Pai said the range is due to various reporting standards worldwide.

Pai said that one in 50,000 seems to be a suitable range in 100,000, but those numbers may change as more vaccines are administered globally.

“Every day we’re giving more shots, and of course, doctors are surveying for cases, so it’s literally changing every hour,” she said.

Seven cases were reported in Canada as of Tuesday, with some of the 1.7 million doses of AstraZeneca’s viral vector product given as of April 24.

Meanwhile, 17 cases of VITT were confirmed in the United States as of April 23 – out of more than eight million doses of Johnson & Johnson’s viral vector vaccine. AstraZeneca is not approved in the United States, and Johnson & Johnson, although authorized in Canada, is not yet used here.

A stroke research specialist and clinical neurosciences professor at the University of Calgary, Drs. Michael Hill stated that this concern is understandable.

He suggested that people look at it another way – one recipient of an AstraZeneca or Johnson & Johnson shot has 99,999 out of a 100,000 odds of fully recovering from 99,999, with the addition of excellent protection from severe COVID-19 Benefit.

“The risk (of getting VITT) is real, it is not zero,” Hill said. “But on the other hand, we have zero risk of anything.”

What is warning

Pai stated that the disorder is an immune response to viral vector vaccines. When antibodies are produced within four to 28 days of the jab, the platelets somehow “switch on” to a reduced number.

“You get this immune event that causes low platelets, and it gives you very aggressive blood clots,” she said.

Pai said it is unclear why a minority of recipients are affected and others are not.

The importance of previous blood clots or family history of clots does not appear, she said, nor is it on the birth control pill – which carries its clotting risk of about 5 in 10,000.

Ling also does not seem to know who is susceptible to VITT, Pa said.

“At first they thought that women were much more likely to get it, but now we have learned that there is only a small possibility.”

What are the signs to look for?

Pai stated that many widespread symptoms may be symptoms of VITT if they occur four to 28 days after receiving the viral vector vaccine.

They include: frequent and severe headaches, difficulty moving parts of your body, seizures, numbness or twitching, shortness of breath, or back, chest, or abdominal pain. Significant changes in an organ – swelling, redness, a pale appearance or a feeling of coldness in one arm or leg – may also indicate clattering.

Hill said that clots usually appear in the head, lungs, legs or abdomen, so the symptoms associated with those body parts should not be ignored. Weitz stated that some VITT clots have been seen in parts of the body that are not commonly associated with clots, including the venous veins that drain the liver, spleen, and bowel.

Rare VITT clots have been observed almost exclusively since the first dose of the viral vector vaccine, but Pai stated that a case was reported after a second dose in the United Kingdom. The person did not experience a clot after their first dose.

“What that tells me is that it is possible (to see VITT after the second dose), but it is very likely that it is also rare (after the first dose),” she said.

What will you do if you think that what you do?

Pai said that people should seek medical care if symptoms emerge. A primary care physician – a family doctor, walk-in clinic or telehealth practitioner – may offer guidance “if symptoms are manageable.”

But if they appear more serious, go to the emergency room.

Hill said that like many other conditions, VITT seems to be easier to treat when caught early.

how did this happen?

A doctor will order a complete blood count (CBC) to determine if the patient’s platelets are low, followed by additional blood tests or imaging – an MRI, for example – to find out if a clot has formed Yes or No.

How is it related?

Effective treatments are available, Pa said, “if initiated in a timely fashion,” including special types of blood thinners and drugs that control the immune system.

She stressed that while rare, clotting disturbances are severe and treatment can be intensive for some.

“It’s not like you take a shot of something and go home,” she said. “Usually this would involve hospitalization and really thoughtful care by many different doctors.”

Hill said doctors are shying away from using blood-thinning heparin in cases of VITT, which seems closely related to HET, or another disorder called heparin-induced thrombocytopenia.

Weitz said that in some cases where platelets are exceptionally low, steroids have been used.

While the death rate in rare VITT cases worldwide is about 20 percent, Weitz said the number is expected to decrease.

“We’re getting better at knowing what it is and how to treat it, diagnosing it first,” he said. “But it’s still not something you want to get.”

This report from The Canadian Press was first published on May 4, 2021.


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