While most patients with COVID will recover fully, others may continue to have symptoms for months or even years after their initial diagnosis. Long-term COVID is diagnosed when symptoms continue after more than 12 weeks.
Up to two hundred symptoms might fall under the umbrella of long COVID. We need to learn what’s causing these symptoms so that we can find effective therapies for them. The possibility that the virus hasn’t been eliminated from the body after the first infection is correlated with prolonged COVID.
Evidence from other viruses shows that viral fragments may persist in various tissues for an extended period of time, often years. It’s possible that this is the situation with SARS-CoV-2, the virus responsible for COVID. This is what the research has found so far.
There are other viruses that may infect the human body.
Herpesviruses (including Epstein-Barr virus, the cause of glandular fever) and HIV (human immunodeficiency virus) may live indefinitely in a “latency state” in the body. That’s because the virus hides within the cells, where it may stay dormant.
Specifically, HIV may lie latent in infected cells all throughout the body. It may still stimulate the immune system and cause inflammation even when it is dormant.
Tissues from sick patients months or years after infection have shown other viruses, including Zika, measles, and Ebola. Viral persistence has been linked to long-term health problems.
Multiple investigations have indicated that COVID may potentially reawaken dormant Epstein-Barr viruses in the body. Long-term COVID has been associated in studies with cognitive impairment and exhaustion.
We need to know how long COVID remains in the body.
SARS-CoV-2 RNA and protein sequences have been detected in tissues and faeces months after infection in many investigations.
Researchers have detected viral RNA and protein in a wide range of organs from people who died up to seven months after infection, as reported in various autopsy reports. SARS-CoV-2 RNA was found in at least 50% of heart, lymph node, eye, nerve, brain, and lung samples.
Viral RNA was detected 4 months after infection in the intestinal tissues of survivors acquired through colonoscopy, in which tissue from the large intestine is removed through a thin tube. At four months, swabs taken from the patients’ noses and throats had tested negative for PCR, indicating that they had asymptomatic COVID.
In the first week after infection, SARS-CoV-2 was detected in the faeces of around half of the trial participants in 2022. Although no virus was found in the respiratory system after 4 months, 12.7% of stool samples tested positive for RNA. At 7 months, stool samples were still positive in 3.8% of cases.
Early research did not consistently indicate a clear correlation between prolonged SARS-CoV-2 detection and persistent COVID symptoms.
How can this prolonged viral clearance affect those with lengthy COVID?
Several mechanisms may contribute to disease due to delayed clearance of SARS-CoV-2 particles in various body parts:
Firstly, irritation. Inflammation, exhaustion, and long-term changes in immune cell function are all the results of constant immunological activation by viral proteins.
Previous research has revealed that people with protracted COVID who originally presented with a mild to moderate illness continue to have immunological dysfunction and inflammation for up to eight months.
Secondly, additional latent viruses may become active. Latent viruses may be reactivated by the immune system’s prolonged reaction to SARS-CoV-2.
People with extended COVID had higher levels of Epstein-Barr virus-specific antibodies, indicating that the virus has reactivated, most likely via stimulating the immune system.
Human endogenous retroviruses (HERVs) are an example of an additional class of dormant viruses that have recently been proven to revive upon infection. COVID patients’ blood cells and tissues had HERV proteins.
These proteins may have a role in initiating inflammation in protracted COVID.
Antibodies created to fight SARS-CoV-2 may develop “self-reactive” properties. These autoantibodies (immune system antibodies that assault healthy tissues and organs) may cause autoimmune illness by reacting with host receptors or proteins.
It is possible that autoimmunity is linked to prolonged COVID, since recent research has revealed that SARS-CoV-2 infection is strongly connected with the emergence of autoimmune illnesses such as type 1 diabetes, inflammatory bowel disease, and psoriasis.
These findings imply that COVID is not only dangerous in the short term but also has the potential to cause significant immune system modifications over the long term.
Although the aforementioned findings provide preliminary evidence for the long-term persistence of SARS-CoV-2 after infection, additional research is required to establish a causal relationship between such persistence and long-term COVID. Regardless of the severity of their illness, people with long-term COVID should have their blood and tissues tested for viral RNA and protein. Also required are worldwide, large-scale, and well-designed cohort studies.
Despite the fact that treating lengthy COVID with antivirals like Paxlovid is still experimental, many studies are now evaluating the efficacy of doing so.
