Earlier this month, Professor David R Walt and colleagues at Harvard Medical School announced that they had detected Sars-CoV-2 proteins – most commonly the viral spike protein – in the blood of 65% of long-term Covid patients, up to and 12. months after their first diagnosis. Although small and preliminary, the study provides some of the most compelling evidence to date on the idea that virus reservoirs could contribute to long-term human health. “The half-life of the spike protein in the body is quite short, so its presence indicates that there must be some kind of active viral supply,” Walt said. Spike protein was not detected in the blood of patients with Covid who did not have persistent symptoms. Walt was motivated to carry out the study after previous research by colleagues found genetic material from the Covid virus (viral RNA) in stool samples from children with multisystem inflammatory syndrome (a rare but serious condition that often occurs about four weeks after conception. Covid). as well as spike protein and intestinal leakage indicator in their blood. Their treatment with a drug that reduced intestinal permeability led to a rapid clearance of the spike protein and improvement of their symptoms. Walt’s working hypothesis is that something similar can happen to people with long Covid. If other groups could replicate Walt’s findings, it would be “enough play” on the idea that the virus pockets did not yet exist in some Covid patients, said Dr Amy Proal, a microbiologist at the PolyBio Research Foundation. a U.S. nonprofit that supports research into complex chronic inflammatory conditions: “I personally do not see a mechanism by which the spike protein could remain for a long time without the virus [being present]. » Other groups have also found evidence that the virus persists – called “viral persistence” – in patients who have recovered from Covid. In April, Ami Bhatt, of Stanford University in California, and colleagues reported that about 13% of people were still passing viral RNA in their stools four months after Covid infection, and nearly 4% continued to does it in seven months. These individuals also reported frequent persistent gastrointestinal symptoms such as nausea, vomiting, and abdominal pain. “The question is whether the continued presence of the virus in the gut or elsewhere can tickle the immune system and cause persistent symptoms,” Bhatt said. A separate study, which analyzed the intestinal tissue of 46 people with inflammatory bowel disease who had recovered from mild Covid, found that viral RNA or proteins could still be detected in 70% of them seven months later. About two-thirds of these people reported persistent symptoms such as fatigue or memory problems – while none of those with a detectable virus did. However, other preliminary research has revealed the virus – in some cases a virus that reproduces – from other anatomical sites, including the eyes, brain and heart, many months after infection. Persistence of the virus is also seen in other diseases, such as Ebola, where the virus is hidden in “anatomical shelters” such as the eyeball or testicles that are less accessible to the immune system – and which are thought to contribute to persistent symptoms such as arthritis. and muscle pain, or fatigue, in many survivors. Even so, conclusive evidence that virus pools contribute to the long-running Covid is still lacking, and Bhatt would like to see further studies done before reaching that conclusion. Some of them are already done. For example, the U.S. National Institutes of Health Recover study looks for signs of coronavirus in stool and intestinal tissue samples from people with long Covid. “These types of studies will be crucial to begin to distinguish what the relationship may be between long-term pools of viruses and long-term Covid,” Bhatt said. If the persistence of the virus actually causes at least one subset of human symptoms, it could also boost research into antiviral drugs as a treatment for long-term Covid. While this may sound trivial, some virologists are concerned about the consequences. “The idea of giving people long-term monotherapy with antivirals to try to clear the virus is quite a controversial issue because, given the adaptation of the virus even in short periods of time, the chances of the virus escaping are extremely high. Said Dr. Deepti Gurdasani, clinical epidemiologist at Queen Mary University of London. “I think we really need to start thinking about double or triple therapies and try them, because we really can’t afford to create more escape mutants right now.” Whether it is tissue sample testing or antiviral drug testing, for those who have been living with Covid for a long time, some for more than two years, such studies may not be done quickly enough.
