Scientists Uncover Hidden Clusters in Long COVID Blood

Scientists at Stellenbosch University have discovered unusual microscopic formations in the blood of people with Long COVID, which may be key to its lasting effects. According to research published on November 13, 2025, clusters of tiny microclots tangled together with sticky immune webs known as neutrophil extracellular traps, or NETs, show up far more often in Long COVID patients, where they appear larger, denser, and more stubborn than in healthy blood. These combined structures, which have been observed in microscope images, form dense clumps that may block tiny blood vessels and reduce oxygen flow, a process thought to play a role in the ongoing symptoms seen in Long COVID. Dr. Chantelle Venter, lead researcher on the project, explained that the microclots and NETs are "like a sticky network that traps immune cells and prevents them from functioning properly." This, she said, could lead to inflammation and tissue damage, contributing to the persistent symptoms experienced by Long COVID patients. The researchers used advanced imaging techniques to visualize the microclots and NETs in the blood of Long COVID patients. They found that these structures were not only more frequent but also larger and more complex than those found in healthy individuals. This suggests that the immune system of Long COVID patients is producing an abnormal response, leading to the formation of these dense clumps. Long COVID, also known as post-acute COVID-19 syndrome, is a condition characterized by persistent symptoms such as fatigue, muscle pain, and cognitive impairment, which can last for weeks or even months after the initial infection. The exact mechanisms underlying Long COVID are still not fully understood, but research suggests that it may be related to the body's immune response to the virus. Dr. Venter noted that the discovery of these microclots and NETs could have significant implications for the treatment of Long COVID. "If we can understand how these structures form and how they contribute to the symptoms of Long COVID, we may be able to develop new therapies to target them and alleviate the suffering of patients," she said. The study's findings have sparked interest in the scientific community, with many experts hailing the discovery as a major breakthrough in the understanding of Long COVID. Dr. John Campbell, a leading expert on COVID-19, said that the research "opens up new avenues for investigation into the mechanisms underlying Long COVID and could potentially lead to the development of new treatments." The researchers are now working to further investigate the role of microclots and NETs in Long COVID, with plans to conduct further studies to confirm their findings and explore potential therapeutic applications. As the scientific community continues to unravel the mysteries of Long COVID, this discovery offers hope for a better understanding of the condition and the development of effective treatments to alleviate the suffering of patients.