What Causes Long COVID?

Let's say you are unlucky and you get COVID. You develop symptoms and generally you expect the symptoms to go away in a week or so. If your symptoms linger for weeks to months, you have what the CDC calls "long COVID."

A new study has shown that pieces of COVID RNA could remain in your body for weeks or even months after the worst part of the infection is over. If these pieces of the viral RNA persist in the body for more than 14 days, you can have serious lingering symptoms, longer hospital stays and a higher chance of death.

Several viruses, like herpes and chicken pox/shingles, are known to stay in the body for a long time. This persistence of the virus may be the key to long COVID. There are many symptoms associated with long COVID- some mild, some debilitating. For many who develop long COVID, this can be a life changing disease. Long COVID is recognized as a serious disease, affecting more than 20 million people in the U.S. alone.

During acute COVID infection, virus is shed from patients' mouths, noses and in fecal material. That is why COVID surveillance examines sewer water to gauge community spread. The highest level of virus in the body is observed during this early stage of the infection. After 10-14 days, most patients' immune systems have reduced the virus, and they generally stop shedding the virus, meaning it can be safe to be around other people without fear of infection. Those who continue to shed virus beyond this time are at risk for more severe issues.

Does the persistence of the COVID virus in the body lead to long COVID? This new study looked at more than 2,500 COVID patients for the presence of virus for an extended time. Here is the surprise. More than 40% continued to test positive 2 weeks after infection, and more than 12% tested positive after 90 days. Other studies have shown that 4% of patients still shed viral RNA in their feces more than six months after diagnosis. All this suggests that there are locations in the body where the virus persists and replicates. This could lead to a persistent inflammatory state, suggesting that our own immune system may be the cause of long COVID.

Some early experiments have treated long COVID patients with the anti-viral drug Paxlovid. This drug keeps the virus from reproducing and is only prescribed for those recently diagnosed with COVID-19 who are at risk of developing severe disease. Identifying the persistence of the virus in the body in those with long COVID symptoms will require much more research.

Your best defense against long COVID? Try not to become infected, or try not to become infected again if, like most of us, you have already had it. That means getting the COVID vaccine and boosters that are available. Recently, scientists showed that vaccination greatly reduced the chance of COVID-19 and long COVID in a study of more than 1 million patients.