New evidence shows that the coronavirus can remain in the blood and tissues for a very long time after the acute phase of infection, which may explain the “root” of long COVID and its complications
The virus after the acute phase of infection with SARS-COV-2 can remain in the blood and tissues of patients for a period that can exceed two years after the acute phase of infection! That’s what a new study by researchers at the University of California, San Francisco (UCSF) showed, which probably gives an explanation as to why some people experience long COVID.
Up to 14 months in blood, over 2 years in tissues
Scientists detected parts of the virus called COVID antigens in the blood of people infected with SARS-CoV-2 up to 14 months after infection. At the same time parts of the virus were detected after more than two years in tissue samples of people who had contracted COVID-19.
The COVID antigens
“The new findings from two studies provide us with some of the strongest evidence to date that COVID antigens can remain in some people’s bodies for long periods of time, even though we think those people have a normal immune response,” Michael said. Peluso, an infectious disease specialist at the UCSF School of Medicine, who led both studies presented at the Conference on Retroviruses and Opportunistic Infections in Denver (the conference took place March 3-6).
Locating the spike protein
In their first study, the researchers examined blood samples from 171 people infected with SARS-CoV-2. They used an ultra-sensitive test to detect the spike protein of the virus that helps it penetrate human cells and found that the coronavirus was still present in some people’s bodies up to 14 months after infection.
Link to severe illness
In fact, the more severe the infection, the greater the chances that the virus would show greater “persistence” within the human body: based on the findings, the probability of detecting COVID antigens was approximately twice as high in people who had needed hospitalization compared to those who had not they had to be hospitalized. The odds were also higher in people who reported having more severe COVID symptoms, even if they had not been hospitalized.
Study in tissues of patients and non-patients
In their second study the researchers turned to the UCSF Long COVID Tissue Bank which contains tissue samples donated by patients with long COVID as well as healthy individuals. Their goal was to find out how long the coronavirus can “nest” in human tissues.
Active virus in tissues
They detected fragments of viral RNA even more than two years after infection even though there was no evidence of reinfection. In particular, the scientists found the virus in the connective tissue where the immune cells are based, which indicates that the parts of the virus were causing the immune system to attack. In some samples the researchers even saw that the virus was still active.
The solution to the riddle of the long COVID and its complications?
Dr. Peluso stressed that further research is needed to determine whether these “persistent” parts of the virus are “guilty” of long-lasting COVID and the complications associated with it, such as heart attacks and strokes.
Testing treatments to “eradicate” the virus from the body
Based on the new findings, the researcher and his colleagues at UCSF are trying to find solutions by testing whether monoclonal antibodies or antiviral drugs can remove the virus from the human body and improve the health of patients with long COVID. “A lot of research still needs to be done, but I feel like we are making progress in understanding the long-term consequences of COVID infection,” concluded Dr. Peluso.
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