Many people struggle longer with symptoms after the corona infection. Why Long-Covid arises is being intensively researched. Some research is now looking at stubborn pieces of the virus that survive in the body. What role so-called coronavirus “ghosts” could play.

The infection goes, the symptoms remain – Sars-CoV-2 often leaves traces in the body of those affected. The symptoms are varied, from headaches to breathing difficulties to exhaustion. What exactly is the cause of Long-Covid is still a mystery to researchers. A review article in the journal Nature sheds light on the fact that fragments of the corona virus could play a role.

Some parts of Sars-CoV-2 can apparently survive for months in the intestines of infected people. Various research teams have found this out. For example, Ami Bhatt from Stanford Medicine in California examined stool samples from Covid 19 patients. Gastrointestinal symptoms such as abdominal pain, nausea and vomiting were related to the fact that those affected also excreted RNA from the coronavirus. However, Bhatt believes the results of the study published in Med could explain more than just the gastrointestinal symptoms of Covid-19. Their findings add to a growing pool of clues: They support the hypothesis that stubborn pieces of virus, coronavirus “ghosts” as Bhatt has dubbed them, may be contributing to the puzzling condition dubbed Long-Covid. This means the pieces of RNA that can often still be detected in the stool months later. The longer gastrointestinal symptoms persist, the more they affect the health of those affected, writes the research team.

“Long-Covid could be the result of an ongoing immune response to Sars-CoV-2,” Bhatt surmised — although it “could also be that we have sufferers with ongoing infections hiding in niches other than the respiratory tract, like the stomach -Intestinal tract,” said the researcher.

The explanation for the ongoing immune reaction would be plausible, also because the intestine plays a major role in our immune system. Because around 70 percent of the human immune defense cells are located in the intestine. More precisely, in the mucous membrane of the digestive organ.

Timon Adolph and his team from the Medical University of Innsbruck came to the same conclusion after analyzing samples from the intestines of infected people. Their results show that if Sars-CoV-2 antigens can be detected in infected tissues, this indicates a cause for Long-Covid.

Researchers also found viral RNA in samples from other parts of the body (biopsies) such as the heart, eyes and brain. Many studies therefore suggest that virus reservoirs can be found in the body – months after the original infection and that these contribute to Long-Covid.

So far, however, the connection has not been clearly proven, even if there are many indications that this is the case. So far, no causality has been shown. For example, gastroenterologist Saurabh Mehandru points out that the coronavirus needs to be shown to develop in people who are not immunocompromised. Scientists would have to associate such a development with long-Covid symptoms. At the moment there would be anecdotal evidence, but many unknowns.

With his 2021 work, Mehandru from the Icahn School of Medicine at Mount Sinai in New York City provided an early indication that the corona virus could persist in the body. So it was clear that cells lining the gut carry the protein that the virus uses to enter the cells. This allows Sars-CoV-2 to infect the intestine.

Given the current evidence, Bhatt hopes samples will become available to test the virus reservoir hypothesis. For example, the US National Institutes of Health is conducting a large study called RECOVER. She is to research the causes of Long-Covid and collect biopsies from the lower intestine.

Remaining virus reservoirs in the body are one of the theories as to the origins of the long-term ailments. Harmful immune reactions or tiny blood clots are also considered possible explanations. Many researchers believe that a mix of these factors leads to it.

What remains to be seen in general is how pronounced the long-Covid problem is with regard to the omicron variants. Some research indicates that it is quite an issue in children. However, other experts assume that long-lasting symptoms are less serious. Because the omicron variants affect less all organs and deep tissue, but rather the upper respiratory tract.

In any case, one thing is becoming apparent in clinical practice, as Jördis Frommhold, chief physician in the department for respiratory diseases and allergies at the Median Clinic in Heiligendamm, told the “Helmholtz Center”: Only very rarely are those treated with long-Covid those with breakthrough infections. That speaks clearly for the vaccination. Jördis added: “In addition to the advantage of a milder course, vaccination can clearly limit both the late effects of intensive care and the likely long-Covid consequences.”

In this country there are now many special outpatient clinics such as the one in Heiligendamm for those affected by long-Covid. In addition, the Federal Center for Health Education (BzgA) has now set up a new online service. Martin Dietrich, Acting Director of the BZgA, said: “Long-Covid is a new type of disease for which there is little reliable knowledge. It is often difficult for those affected and their relatives to find suitable information and support services. This is where the new online service comes in: it is both a source of information and a guide to help and advice. It is also intended to increase public awareness of Long-Covid so that those affected can find suitable help more quickly.”

The website offers interested parties quality-checked information. In addition to answers to common questions, those affected and their families will also find information on support options and recommendations for everyday life.

In addition, the site provides information on the subject of “Long-Covid in the workplace” for both employers and employees: contains, among other things, information on support offers in the work context and specifically for employers.