Long COVID Might be Caused by Virus Hanging Out in Your Gut

 

As noted in an earlier post, one of the risks of contracting SARS-CoV-2 is that it may turn into a chronic disease referred to in medical terms as "post-acute sequelae of COVID-19" (PASC). It is known colloquially as long-haul or just long COVID. The CDC says the condition can last anywhere from weeks to years. 

They give a long list of possible symptoms, but note that some of them can be "hard to explain and manage:"

Clinical evaluations and results of routine blood tests, chest x-rays, and electrocardiograms may be normal. The symptoms are similar to those reported by people with ME/CFS (myalgic encephalomyelitis/chronic fatigue syndrome) and other poorly understood chronic illnesses that may occur after other infections. 

Unlike other aspects of the disease where the oldest fare the worst, long COVID is more likely to affect younger people, according to a data from people with private health insurance.  Nearly a third of victims are 35 or younger, and the most-affected age group is 36-50.

A recent preprint from Harvard Medical School showed that spike proteins of the virus could be detected in the blood of people with PASC twelve months after their infection, but not in the blood of people without PASC. One of the mysteries is how this can happen when the virus is no longer detectable with PCR tests.

One of the researchers said: “The half-life of spike protein in the body is pretty short, so its presence indicates that there must be some kind of active viral reservoir." Where is it hiding, then? 

The gut is a leading candidate. One study found that 13% of people who'd had COVID-19 shed viral DNA in their feces four months after their initial infection, and 4% continued to do so after seven months.

Another study found viral DNA in the gut mucosa of people with inflammatory bowel disease seven months after their initial reflection. Other research has reportedly found the virus in tissue of the eyes, brain, and heart.

The gut connection, especially, might be one reason there have not been definitive links established between virus levels in wastewater samples and case rates in the same area. If you look at the BioBot site, you will see that in the graph for the U.S. overall, the correlation between the lines for wastewater and cases looks very solid.

But look at the graphs for individual counties, and you will see lots of instances where the wastewater level is high and the case rate stays low, and vice versa. Could that be because there are people with virus in their gut who aren't counted as actively infected?

Maybe. It could also have something to do with the very spotty nature of the wastewater data. We also shouldn't forget that most experts now consider case data to be very questionable, because reporting standards have changed and people have moved to the at-home tests.