Covid can persist in the blood and tissues of patients for more than a year after the end of the acute phase of the disease, according to new research from the University of California San Francisco.
Scientists have found fragments of Sars-CoV-2, called Covid antigens, persisting in the blood for up to 14 months after infection and for more than two years in tissue samples of people affected by the virus.
The findings were presented at the Conference on Retroviruses and Opportunistic Infections (CROI), which was held March 3-6, 2024 in Denver.
At the beginning of the pandemic, Covid-19 was thought to be a transient disease.
But a growing number of patients, even those who were previously healthy, continued to have symptoms such as mental confusion, digestive problems and vascular problems, for months or even years.
The researchers examined blood samples from 171 people who had been infected with Covid.
Using an ultrasensitive test for the Spike protein, which helps the virus penetrate human cells, they found that the virus was still present up to 14 months later in some people.
Among those who were hospitalized for Covid, the chance of detecting antigens was about double.
Since the virus is believed to persist in tissue reservoirs, researchers then turned to the Long Covid Tissue Bank, which contains samples donated by patients with and without Long Covid.
They detected portions of viral RNA up to two years after infection, although there was no evidence that people had become reinfected.
They found it in the connective tissue where immune cells are located, which suggests that viral fragments may cause the immune system to attack.
The researchers highlight that further studies are needed to determine whether the persistence of these fragments determines Long Covid and associated risks such as heart attack and stroke.
But, based on these findings, the research team is involved in several clinical trials that are testing whether monoclonal antibodies or antiviral drugs can remove the virus and improve the health of people with Long Covid.
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