COVID remnants still show up on PET/CT scans years after infection
For some people, evidence of immune responses from contracting COVID-19 can be seen in multiple organs years after recovering from the virus.
That’s according to new PET imaging data detailing the presence of activated T cells in the brain, spinal cord, gut and lung tissues of individuals who have recovered from COVID. The latest data add to the mounting evidence that the remnants of COVID may not completely clear for everyone and can linger in the body well after its acute threat has been diminished, experts involved in the research suggested.
“The mechanisms of post-acute medical conditions and unexplained symptoms after SARS-CoV-2 infection are incompletely understood. There is growing evidence that viral persistence, immune dysregulation, and T cell dysfunction may play major roles," Michael J Peluso, with the division of HIV, infectious diseases, and global medicine at the University of California, San Francisco, and colleagues noted.
For the study, researchers deployed a radiotracer ([18F]F-AraG) that binds to activated T lymphocytes. Whole-body PET scans were conducted using the radiotracer on a group of 24 individuals, both with and without persistent symptoms, at varying time points (27 to 910 days) after recovering from their initial COVID infection. Their scans were then compared to those from a group of matched prepandemic controls.
In the post-COVID group, heightened tracer uptake was observed in the brain stem, spinal cord, bone marrow, nasopharyngeal and hilar lymphoid tissue, cardiopulmonary tissues and gut wall. Increased uptake in the spinal cord and gut wall was associated with long COVID symptoms; similar findings were observed among individuals with tracer uptake in their lung tissue, as those people reported persistent pulmonary symptoms.
The high uptake observed in the gut prompted the team to perform further histochemical analysis of some of the participants’ colorectal tissue. This revealed the presence of SARS-CoV-2 spike protein–encoding RNA in every individual tested, including one that was nearly 700 days out from their initial infection.
Combined, these findings suggest that “tissue viral persistence could be associated with long-term immunologic perturbations,” the group wrote.
Though the study was small, the team suggested that their findings were significant and warrant further research with larger cohorts.
The study abstract can be found in Science Translational Medicine.
In addition to her background in journalism, Hannah also has patient-facing experience in clinical settings, having spent more than 12 years working as a registered rad tech. She joined Innovate Healthcare in 2021 and has since put her unique expertise to use in her editorial role with Health Imaging.