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medicine

School of Medicine review proposes treatments for COVID-related blood clots

Yale News

Scientists at Yale have synthesized research from around the world to suggest new treatment methods for COVID-19.

A multidisciplinary team of Yale physician scientists, researchers, nursing staff and others have collaborated since early on in the pandemic to figure out why COVID-19 patients are so prone to blood-clotting. Their recent review, published on Nov. 19 in Nature Reviews Cardiology, details how COVID-19 causes blood clots in sick patients and why the disease has been so difficult to treat.

“Blood clotting is a complex process that involves many types of cells in the body including platelets and endothelial cells,” John Hwa, professor of medicine at the Yale Cardiovascular Research Center and one of the review’s senior authors, wrote in an email to the News. “It isn’t often that all components involved are in serious disarray and thus synergizing to promote massive blood clotting. In some ways it’s like ‘a perfect storm’ where all the components are perturbed and are tipped over the edge by COVID-19.”

Hwa said his colleague Hyung Chun, co-author of the review and director of Translational Research at the Yale Pulmonary Vascular Disease Program, contacted him in March when he suspected that endothelial cells, which line the interior surface of blood vessels, might be involved in the pathogenesis of COVID-19. 

Alfred Lee, associate professor of Medicine and another author of the review, also reached out to Hwa in March and informed him of potential abnormalities in platelets — cells responsible for blood clotting — that he was observing in COVID-19 patients. The team, which included Lee, Hwa and Chun, expanded those observations into a massive collaborative effort that included many frontline healthcare workers helping with patient treatment.

Platelets and endothelial cells are not usually considered important in the development of a disease from viral infection, according to Hwa. But COVID-19 and the body’s resulting immune response can lead to damage in many different cells and cause a wide range of complications — including those related to platelets and endothelial cells.

“A major adverse outcome of those critically ill with Covid19 is formation of blood clots, many of which are likely undiagnosed,” Chun wrote in an email to the News. “This is likely occurring due to a combination of endothelial injury/activation and platelet activation.”

To make matters worse, the functions of these cells can already be compromised in elderly people and in people with diabetes or other cardiovascular risk factors. Then, when the cells are introduced to COVID-19, the “perfect storm” that Hwa described forms. 

Another complication can come in the form of elevated cytokine levels, according to Jennifer Kwan, co-author of the review and clinical fellow at the Yale School of Medicine.

“The cytokines are essentially our messaging system released by immune cells to ramp up the immune defense or offense against a microbial threat,” Kwan said. “But when

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health

Health panel proposes colon cancer tests start at 45, not 50

NEW YORK (AP) — A panel of health experts wants U.S. adults to start getting colon cancer screenings at age 45, five years younger than it previously recommended.

While overall, colon cancer rates have been declining, the draft guidelines issued Tuesday by the U.S. Preventive Services Task Force reflect a growing concern about rising rates in people under the age of 50.

“We’ve seen more data showing that younger people are getting colon cancer at higher rates,” said Dr. Alex Krist, a family doctor at Virginia Commonwealth University and a member of the task force. “Basically a 45-year-old today has the same risk of getting colon cancer as a 50-year-old from years past.”

The task force is a volunteer panel of doctors that regularly reviews evidence and issues advice on medical tests and treatments.

The group is proposing that adults of average risk for colon cancer be screened from ages 45 to 75. How often the tests are done depends on the type of screening: a colonoscopy is usually every five to 10 years while stool-based tests are every year.


“Most people who get colon cancer have no signs, no symptoms and no risks. And so that’s why we recommend that everyone get screened,” Krist said.

More frequent testing is recommended for those with abnormal colon polyps or a family history of colon cancer or genetic disorders that increase their risk for the disease. Tuesday’s proposal also emphasizes that the disease occurs more often, is screened for less and leads to more deaths in Black adults.

Colon cancer, along with rectal cancer, is the third leading cause of cancer deaths in the U.S., with an estimated 148,000 new cases this year.

The task force proposal brings it in line with guidelines from the American Cancer Society, which in 2018 lowered the screening age from 50 to 45. With the change, doctors should feel comfortable recommending colon cancer screens to younger patients, said the cancer group’s Robert Smith.

“We’ve been anticipating this for a while,” Smith said.

Earlier testing would help detect precancerous polyps or early cancer in younger patients before the disease requires more aggressive treatment, said Dr. Nancy You of MD Anderson Cancer Center in Houston.

“We have a lot more treatment options that are less invasive and have better results when we treat cancer at the earlier stages,” she said. “That makes a huge difference to our patients.”

Experts anticipate it will still be a challenge getting people screened. Currently, 1 in 4 people between 50 and 75 have never been screened for the disease, and only about 60% of U.S. adults are up to date on their colon cancer screenings, Krist said.

If the recommendations are finalized, screenings for younger people would be covered by most private insurance plans, with no copay. The Affordable Care Act mandates that insurers cover services recommended by the task force.

The proposal is open for public comment through Nov. 23.

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Follow Marion Renault on Twitter: @MarionRenault

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The Associated Press

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