Research Roundup: Why Blood Clots in COVID-19 and More

Every week there are numerous scientific studies published. Here’s a look at some of the more interesting ones.

Cause of COVID-19 Blood Clots Identified

Although COVID-19 has a fairly broad range of effects, one of the more peculiar has been blood clots. Researchers at the Michigan Medicine – University of Michigan identified a mechanism of how this happens. They appear to be caused in about half of patients having blood clots by an autoimmune antibody found in the blood that attacks cells and triggers blood clots. In COVID-19, these minuscule clots may also restrict blood flow in the lungs, which impairs oxygen exchange. In patients without COVID-19, these antibodies are typically seen in the autoimmune disease antiphospholipid syndrome. The research was published in the journal Science Translational Medicine.

“In patients with COVID-19, we continue to see a relentless, self-amplifying cycle of inflammation and clotting in the body,” said Yogen Kanthi, assistant professor at the Michigan Medicine Frankel Cardiovascular Center and a Lasker Investigator at the National Institutes of Health’s National Heart, Lung and Blood Institute. “Now we’re learning that autoantibodies could be a culprit in this loop of clotting and inflammation that makes people who were already struggling even sicker.”

The clinical implications aren’t yet clear, but they want to evaluate whether severely sick COVID-19 patients with high levels of the antibodies would have better outcomes if the antibodies are blocked or removed. One potential therapy, which is aggressive, is plasmapheresis, which is used to treat severe autoimmune diseases. Plasmapheresis involves separating the plasma from the blood and replacing it with saline or albumin, then filtering the plasma and returning it to the body.

The researchers are currently running a clinical trial called DICER that is testing dipyridamole, an anti-clotting drug, in COVID-19 patients to determine if it’s more effective than placebo in decreasing excessive blood cloths.

“Dipyridamole is an old drug that is safe, inexpensive, and scalable,” Kanthi said. “The FDA approved it 20 years ago to prevent clotting, but we only recently discovered its potential to block this specific type of inflammation that occurs in COVID.”

Six Times the Rate of COVID-19 in Bavarian Children than Previously Reported

Researchers at Helmholtz Zentrum München, the German Research Center for Environmental Health, analyzed blood samples of almost 12,000 children in Bavaria between the ages of 1 to 18 between January 2020 and July 2020. They tested for SARS-CoV-2 dual-antibody positivity. They identified an average antibody frequency of 0.87% from April to July, which was six times higher than the incidence of virus-positive cases reported by the Bavarian Health and Food Safety Authority in the same period. They found that 47% of the children who tested antibody-positive were asymptomatic.

How Allergens Trigger Itching

Scientists at Massachusetts General Hospital identified a neuropeptide called Substance P that certain neurons in the skin release when they detect allergens. Substance P is necessary for allergen-induced immune responses. The ways in which the immune system responds to pathogens is well understood, but how it responds to allergens like pollen, dust mites or animal fur is not as clear. They did know that dendritic cells activate T cells that are required for the immune response, but until this discovery, they did not know how the allergen exposure led to itching. The dendritic cells are located next to allergen-responsive neurons in the skin. When exposed to an allergen, the neurons release Substance P, which directly creates migration of the dendritic cells to the lymph nodes, where they activate T cells. The T cells then trigger the immune response against the allergen.

COVID-19 Super-Spreading Events More Common and More Dangerous

A COVID-19 super-spreading event is defined as where one person with COVID-19 infects more than six other people. Research out of the Massachusetts Institute of Technology (MIT) analyzed 60 super-spreading events and found that they are more common than previously thought and play a larger role in overall disease transmission. The investigators found that for SARS-CoV-2, the “basic reproduction number” is about three, which means that on average, each person infected will pass it on to about three other people, but it can vary from person to person. But so-called “super-spreaders” can infect dozens of people. In the super-spreading events they analyzed, 45 from the current COVID-19 pandemic and 15 from the 2003 SARS-CoV outbreak, they found that between 10 and 55 people were infected, but two of them, both from the 2003 outbreak, involved more than 100 people. They also found that these super-spreaders have a “long tail,” meaning they continue to infect people long after the original exposure event. It supports the idea that groups involving 10 or more people should be advised against to help slow the spread of COVID-19.

Gum Disease Linked to Precancerous Cells that Can Lead to Colorectal Cancer

Harvard researchers published research that studied the development of two types of irregular cells in the colon, serrated polyps and conventional adenomas, which can lead to colorectal cancers. In their study of 42,486 people, they found that individuals with gum disease had a 17% higher risk of developing serrated polyps and an 11% higher risk of developing conventional adenomas. In people whose gum disease resulted in losing four or more teeth, the risk was 20% higher of developing serrated polyps and a 36% higher risk of developing advanced conventional adenomas; people who had lost one to three teeth had a 28% higher risk of advanced conventional adenomas. The correlation isn’t well understood, and they note that periodontal diseases are related to other factors, including socioeconomics, diabetes and obesity.

Testing Different Materials for Face Masks

Investigators at the University of Cambridge tested a broad range of materials, from T-shirts and socks to jeans and vacuum bags, to find out what type of material was most effective for use in face masks to trap particles that might contain SARS-CoV-2, the virus that causes COVID-19. The fabrics ranged between 0.02 and 0.1 micrometers, approximately the size of most viruses, at high speeds, similar to that seen with coughing or heavy breathing. They also evaluated N95 and surgical masks. The data demonstrated that most of the materials commonly used for non-clinical masks were effective at filtering ultrafine particles, whereas N95 masks were “highly effective.” A reusable HEPA vacuum bag exceeded the N95 masks in some areas.

“We’ve shown that in an emergency situation where N95 masks are not available, such as in the early days of this pandemic, fabric masks are surprisingly effective at filtering particles which may contain viruses, even at high speeds,” said Eugenia O’Kelly, first author of the study published in BMJ Open, and an engineer from Cambridge’s Department of Engineering.