The article you just read was brought to you by a few thousand dedicated readers. Will you join them?

Thanks for coming by The Tyee and reading one of many original articles we’ll post today. Our team works hard to publish in-depth stories on topics that matter on a daily basis. Our motto is: No junk. Just good journalism.

Just as we care about the quality of our reporting, we care about making our stories accessible to all who want to read them and provide a pleasant reading experience. No intrusive ads to distract you. No paywall locking you out of an article you want to read. No clickbait to trick you into reading a sensational article.

There’s a reason why our site is unique and why we don’t have to rely on those tactics — our Tyee Builders program. Tyee Builders are readers who chip in a bit of money each month (or one-time) to our editorial budget. This amazing program allows us to pay our writers fairly, keep our focus on quality over quantity of articles, and provide a pleasant reading experience for those who visit our site.

In the past year, we’ve been able to double our staff team and boost our reporting. We invest all of the revenue we receive into producing more and better journalism. We want to keep growing, but we need your support to do it.

Fewer than 1 in 100 of our average monthly readers are signed up to Tyee Builders. If we reach 1% of our readers signing up to be Tyee Builders, we could continue to grow and do even more.

If you appreciate what The Tyee publishes and want to help us do more, please sign up to be a Tyee Builder today. You pick the amount, and you can cancel any time.

Support our growing independent newsroom and join Tyee Builders today.
Before you click away, we have something to ask you…

Do you value independent journalism that focuses on the issues that matter? Do you think Canada needs more in-depth, fact-based reporting? So do we. If you’d like to be part of the solution, we’d love it if you joined us in working on it.

The Tyee is an independent, paywall-free, reader-funded publication. While many other newsrooms are getting smaller or shutting down altogether, we’re bucking the trend and growing, while still keeping our articles free and open for everyone to read.

The reason why we’re able to grow and do more, and focus on quality reporting, is because our readers support us in doing that. Over 5,000 Tyee readers chip in to fund our newsroom on a monthly basis, and that supports our rockstar team of dedicated journalists.

Join a community of people who are helping to build a better journalism ecosystem. You pick the amount you’d like to contribute on a monthly basis, and you can cancel any time.

Help us make Canadian media better by joining Tyee Builders today.
We value: Our readers.
Our independence. Our region.
The power of real journalism.
Get our free newsletter
Sign Up

New Scientific Insights on COVID-19 and Blood Clotting

Why it matters researchers call this ‘the first viral disease that can be branded as a viral thrombotic fever.’

Crawford Kilian 16 Apr 2021 |

Tyee contributing editor Crawford Kilian blogs about the pandemic.

Fifteen months ago, no one even knew the SARS-CoV-2 virus existed, let alone that it was about to infect scores of millions of people. Since then it’s been studied with rare intensity, and we’ve learned enough to produce an array of vaccines against it in a very brief time.

Now we’re fretting about the safety of some of those vaccines and the possibility that the AstraZeneca vaccine, in particular, may cause very rare cases of blood clots. Health Canada says it’s safe, but scare stories about such side effects tend to discourage vaccine acceptance. That hesitancy gives the virus and all its variants more chance to spread and infect more of us.

Now a Brazilian research team has learned something else about COVID-19, the disease the virus causes: it’s the first “viral thrombotic fever.” That is, one of its most dangerous symptoms is its ability to create blood clots. If they’re right, we may have a whole new way to fight the disease. And it should put in perspective overblown fears of the AstraZeneca vaccine.

On April 14, the team published its report in Memórias do Instituto Oswaldo Cruz, a journal of Brazil’s top medical institute (usually known as Fiocruz).

“The name COVID-19 tells us very little about the true meaning of the disease,” they argued. “Our proposal is more comprehensive; it intends to frame COVID-19 in more clinical terminology, making an analogy to Viral Hemorrhagic Fever. Thus, we found irrefutable evidence in the current literature that COVID-19 is the first viral disease that can be branded as a Viral Thrombotic Fever.”

From hemorrhagic to thrombotic

Many viral diseases like Ebola, Marburg, and dengue are “hemorrhagic” — many of those infected suffer bleeding from the eyes, nose and other parts of the body. The bleeding isn’t usually fatal, but it’s a sign of the damage the virus is doing to the victim’s circulatory system.

But with COVID-19, the damage done to the system results in blood clots: “COVID-19 infections promote remarkable interactions among the endothelium, coagulation and immune response, building up a background capable of promoting a ‘thrombotic storm,’ much more than a ‘cytokine storm,’” the researchers write. A cytokine storm is the immune system’s over-reaction to infection, and it can be as damaging as the infection itself. A thrombotic storm would generate clots, triggered by a viral protein called Mpro. When a virus-infected cell dies and releases hordes of new viruses, Mpro is released also.

Clotting was recognized as a problem very early in the pandemic: Last April, the Washington Post published a report on patients in their 30s and 40s, some with very mild symptoms, who were being crippled by a kind of stroke usually seen in very old people. Clots were also turning up in patients’ lungs, causing pulmonary embolisms, and in their hearts — causing heart attacks.

Mpro, the Brazilians say, can damage the endothelium, the lining of blood vessels. That could make it easier for viruses to reach the nervous system and brain, causing neurological damage: loss of the sense of smell, epilepsy, and perhaps some of the symptoms of long COVID that persist well after recovery.

Not all COVID-19 cases suffer from clots, but the Brazilians cite findings that 16 per cent of cases in intensive care had problems from excessive formation of blood clots; a French survey found over 40 per cent. It’s also possible that much of the excess mortality seen around the world is due to undiagnosed strokes.

Misplaced vaccine anxieties

The Fiocruz report concludes by saying, “It is important to say that our purpose in this opinion was to describe possible phenomenological mechanisms that can help in understanding the reasons why thrombotic phenomena are such a central hallmark of COVID-19. It was not our intention to generate or recommend therapeutic actions.” But their findings, if confirmed, certainly point the way to potential therapies that would minimize clotting — anything from aspirin to all-new attacks on Mpro and other clotting factors.

The Brazilian report gives us a new perspective on COVID-19 as a viral thrombotic fever. Their findings also make our anxieties about AstraZeneca look misplaced. Not only are the odds of a vaccine-induced clot about one in 250,000, but clots caused by COVID-19 itself are up to 100 times more likely.

Vaccine hesitancy, then only worsens the odds against us. As Damon Runyon once observed, “The race is not always to the swift, nor the battle to the strong, but that’s the way to bet.”  [Tyee]

Read more: Coronavirus

Share this article

The Tyee is supported by readers like you

Join us and grow independent media in Canada

Facts matter. Get The Tyee's in-depth journalism delivered to your inbox for free

Tyee Commenting Guidelines

Do not:

  •  Use sexist, classist, racist or homophobic language
  • Libel or defame
  • Bully, threaten, name-call or troll
  • Troll patrol. Instead, downvote, or flag suspect activity
  • Attempt to guess other commenters’ real-life identities


  • Verify facts, debunk rumours
  • Add context and background
  • Spot typos and logical fallacies
  • Highlight reporting blind spots
  • Ignore trolls and flag violations
  • Treat all with respect and curiosity
  • Stay on topic
  • Connect with each other


The Barometer

Tyee Poll: Are You Preparing for the Next Climate Disaster?

Take this week's poll