As the coronavirus pandemic enters its 11th month, and case counts continue to set terrifying records, potentially fatal blood-clotting has emerged as one of the most frustrating health risks posed by the deadly disease.
Now teams of scientists are racing to test therapies that might be able to prevent the clots. One major effort is giving people blood-thinners to patients with moderate coronavirus infections. Another is dosing COVID patients in intensive care. Their success could have a major impact on just how deadly coronavirus remains as the pandemic enters its second year.
Welcome to Rabbit Hole, where we dive deep on the biggest story. It’s for Beast Inside members only. Join up today.
All these months into the pandemic, the SARS-CoV-2 virus continues to surprise and befuddle clinicians, and that includes how it affects human blood.
“A great mystery of COVID-19 is that it can vastly increase the risk of fatal blood clots,” Lawrence Gostin, a Georgetown University global health expert, told The Daily Beast. “No other virus that we are aware of has the same pronounced impact.”
It’s unclear exactly what percentage of COVID patients suffer dangerous clotting, but it could be as high as 30 percent in people whose infections are serious enough to warrant hospitalization, one research group found.
The danger is obvious. Blood clots can travel to the lungs and cause a thrombosis. Or to the brain and cause a stroke. Or to the heart, potentially resulting in a heart attack. “If we can effectively treat blood clots in critically ill COVID-19 patients, we could save many lives,” Gostin said.
Anticoagulant and antiplatelet blood-thinners could be the key.
There’s a possible downside, of course: Thinning the blood might prevent clots, but it also raises the risk of uncontrolled bleeding.
To mitigate this risk and help physicians tailor treatment, researchers in two study groups are exploring different mixes and courses of treatment with blood-thinners on patients with varying severity of infections.
The separate efforts, while totally independent of each other, are working toward a common goal. While some clinicians are already administering blood-thinners for the treatment of COVID side-effects, there are no firm guidelines for the practice. The dual trials could take a lot of the guesswork out of the blood-thinners as a COVID therapy.
“The two trials should produce complementary results,” Kraig Kumfer, an expert in blood clotting at the University of Wisconsin who is involved in one of the trials, told The Daily Beast.
The first major trial, “Prevention of Arteriovenous Thrombotic Events in Critically-Ill COVID-19 Patients Trial,” or “COVID-PACT,” launched at Brigham and Women’s Hospital in Boston in June. COVID-PACT is currently enrolling 750 volunteers at ICUs in hospitals across the United States and could begin reporting findings next May.
COVID-PACT is focusing on the critically ill patients who are at high risk of blood clots. The volunteers get the blood thinners Clopidogrel, Enoxaparin, and Heparin, all of which have approval from the U.S. Food and Drug Administration and are readily available. After two weeks, the investigators use ultrasound to scan the patients’ legs, looking for clots.
One aim of the COVID-PACT study is to balance, in really sick COVID patients, the benefits of thinner blood against the risk of, well, blood that’s too thin. “There is also insufficient data regarding the bleeding risk in this population,” Sinha Shashank, a cardiologist with the Inova Medical Group in Virginia who is involved in the COVID-PACT trial, told The Daily Beast.
Another aim of the Brigham and Women’s Hospital trial is to test out different types of blood thinners. Anticoagulants such as Heparin slow down clotting. Antiplatelet agents such as Clopidogrel prevent platelets from clumping and so prevent clots from ever forming.
Think of anticoagulants and antiplatelets as two slightly different solutions to the same problem. The COVID-PACT trial could produce comparative data between the two drug types in addition to gathering information on when and how much a clinician should administer blood-thinners.
“I think it will answer important questions regarding the utility of full versus prophylactic anticoagulant use and whether antiplatelet agents are helpful,” Christopher King, a pulmonary and critical-care specialist with the Inova Medical Group in Virginia, told The Daily Beast.
While COVID-PACT is running tests with ICU patients, a separate trial out of New York University is giving blood-thinners to patients with only moderate COVID. The “Anti-thrombotics for Adults Hospitalized With COVID-19” or “ACTIV-4” trial began enrolling 2,000 volunteers back in August. It, too, is aiming to publish results in the spring.
ACTIV-4’s goal is simple. “The ACTIV-4 trial is a [National Institutes of Health]-sponsored, pragmatic trial that seeks to address the optimal dosing of anticoagulation for patients with COVID-19,” said Kumfer, one of the trial’s investigators. In other words, just how much Heparin is enough Heparin to prevent clots without also causing bleeding.
If the trials go well, by next spring doctors could look to them for guidance on preventing clotting in COVID patients. That, in turn, could help head off some of the worst impacts of a pandemic that looks like it isn’t going anywhere soon.
“That is the exact type of clinical trial that needs to be done to advance COVID-19 therapy,” Jeffrey Klausner, a professor of medicine and public health at UCLA, told The Daily Beast. “We cannot rely on anecdotes or case-reports but must be informed by randomized clinical trials. That is the highest standard of evidence.”
