sFrom the early days of the pandemic, it has been clear that some people shed genetic material from the virus in their faeces for several months after contracting Covid-19. The findings were initially considered a curiosity, but there is mounting evidence to support the idea that persistent pockets of coronavirus – in the gut or elsewhere – may contribute to the spread of Covid.
Earlier this month, Professor David R. Walt and colleagues at Harvard Medical School announce They detected Sars-CoV-2 proteins – the most common viral spike protein – in the blood of 65% of Covid patients who tested for a long time, up to 12 months after they were first diagnosed.
Although small and preliminary, the study provides some of the most compelling evidence to date on the idea that virus reservoirs can contribute to people’s long-term ill health. “The half-life of the spike protein in the body is very short, so its presence suggests that there must be some kind of active viral reservoir,” Walt said.
No spike protein was detected in the blood of Covid patients who did not have persistent symptoms.
Walt was excited to conduct the study after his colleagues’ previous research discovered 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 infection with Covid). Beside Spike Protein And the sign of the intestines leakage in their blood. Treating them with a drug that reduced intestinal permeability quickly eliminated the spike protein and improved their symptoms. Walt’s working hypothesis is that something similar might happen in people with prolonged Covid-19.
Dr. Amy Brual, a microbiologist at the PolyBio Research Foundation, said that if other groups could replicate Walt’s findings, it would be “largely over” for the idea that pockets of virus haven’t been present in at least some Covid patients for so long. US nonprofit supporting research into complex chronic inflammatory conditions: “I personally do not see a mechanism by which spike protein can persist over long periods of time without the virus.” [being present]. “
Other groups have also found evidence of persistent presence of the virus – called ‘viral persistence’ – in patients who have recovered from Covid. In April, Amy Bhatt, of Stanford University in California, and colleagues mentioned that about 13% of individuals were still shedding viral RNA in their faeces four months after contracting Covid, and nearly 4% continued to do so for seven months. These people also often reported persistent gastrointestinal symptoms such as nausea, vomiting, and abdominal pain.
“The question is whether continued presence of the virus in the gut or elsewhere might tickle the immune system, and cause persistent symptoms,” Bhatt said.
sporadic Research, who analyzed intestinal tissue from 46 people with IBD who had recovered from mild Covid disease, and found that viral RNA or proteins could still be detected in 70% of them after seven months. Nearly two-thirds of these individuals reported persistent symptoms such as fatigue or memory problems — while none of those without a detectable virus did.
However, other preliminary research has been successful in recovering the virus – in some cases replication of the virus – from other anatomical sites including the eyes, brain and heart several months after people became infected.
The persistence of the virus is also seen in other diseases, such as Ebolawhere the virus hides in “anatomical havens” such as the eyeball or testicles that are hard for the immune system to reach – which are thought to contribute to persistent symptoms such as joint and muscle pain, or fatigue, in many survivors.
However, conclusive evidence that viral reservoirs contribute to the prolonged spread of Covid is still lacking, and Bhatt would like to see more studies before reaching that conclusion.
Some of these are already taking place. For example, the US National Institutes of Health Study recovery It looks for signs of MERS infection in stool and intestinal tissue samples from people with long-term COVID-19. “These types of studies will be critical to start deconstructing the relationship between long-term viral reservoirs and long-term Covid,” Bhatt said.
If persistence of the virus really drives at least a subset of people’s symptoms, it may also prompt investigation of antiviral drugs as a treatment for Covid for a long time. Although this may seem like a no-brainer, some virologists are concerned about the implications of doing so.
“The idea of giving people a single, long-term antiviral treatment to try to get rid of the virus is a very controversial issue, given how well adapted the virus we see even in short periods of time, the probability of the virus escaping is very high,” said Dr. Deepti Gordasani, a clinical epidemiologist. at Queen Mary University, London. “I think we really need to start thinking about dual or triple therapies, and experimenting with them, because we can’t really create more escape mutants at this time.”
Whether it is examining tissue samples, or trials of antiviral drugs, for those who have been living with Covid for a long time, some for more than two years, such studies cannot come fast enough.
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