Hidden Immune Damage That Cannot be Detected by Routine Serology Found in Long COVID Patients
Nikhil Prasad Fact checked by:Thailand Medical News Team May 14, 2026 50 minutes ago
Medical News: A major new study has found that many people suffering from long COVID may be experiencing hidden immune system damage that cannot be detected using routine laboratory testing. The findings are raising serious concerns that standard medical screening methods are failing to identify ongoing immune abnormalities in millions of patients still struggling months after COVID-19 infection.
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The study was conducted by researchers from the University of Debrecen, University of Pécs, Semmelweis University, the Institute for Translational Research in Hungary, and the University of Oklahoma Health Sciences Center in the United States. The scientists investigated whether long COVID patients develop tissue-specific autoantibodies that attack organs such as the heart, lungs, and blood vessels.
Scientists Discover Hidden Autoimmune Reactions
Autoantibodies are abnormal immune proteins that mistakenly attack the body’s own tissues. They are commonly linked to autoimmune diseases such as lupus and rheumatoid arthritis.
In this study, researchers analyzed blood samples from 114 long COVID patients and compared them with samples collected before the COVID-19 pandemic. Using advanced tissue-based testing methods, they discovered that 83 percent of long COVID patients carried hidden tissue-specific autoantibodies, compared to only 53 percent of the control group.
The strongest immune abnormalities were directed against cardiovascular tissues, especially blood vessels and heart tissues. Vascular autoantibodies were significantly more common in long COVID patients than in healthy controls, suggesting that ongoing blood vessel injury could be one of the major drivers behind lingering symptoms.
Researchers also found that many patients carried multiple autoantibodies targeting different tissues at the same time, revealing widespread immune dysregulation rather than isolated immune abnormalities.
Routine Tests Failed to Detect the Problem
One of the most disturbing findings was that standard autoimmune blood tests failed to identify these immune disturbances.
The commonly used ANA HEp-2 screening test, routinely performed in hospitals to detect autoimmune disorders, showed little value in distinguishing long COVID patients from healthy individuals. However, the specialized tissue-based Western blot testing used in the study uncovered extensive hidden immune activity that routine serology completely missed.
This means many long COVID patients may continue suffering from immune-related damage while their standard blood test results appear normal. The researchers warned that current medical testing approaches may be insufficient for properly diagnosing immune complications associated with long COVID.
Strong Links to Symptoms and Neurological Problems
The study also found important connections between these hidden autoantibodies and common long COVID symptoms.
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Patients with heart-related autoantibodies were more likely to suffer from headaches and hypertension. Meanwhile, patients with broader autoantibody activity showed a strong association with anosmia and ageusia, the persistent loss of smell and taste often reported after COVID infections.
Researchers observed that the majority of these autoantibodies belonged to the IgM category rather than the IgG category normally associated with long-term immunity. This unusual pattern suggests that the immune system may remain trapped in a chronic state of abnormal activation long after the virus has disappeared.
Follow-up testing performed several months later showed that these IgM autoantibodies often persisted over time. Some patients even developed new autoantibodies during follow-up instead of improving.
This
Medical News report notes that the findings strongly suggest that long COVID may involve a prolonged autoimmune-like process that continuously damages tissues and blood vessels in certain patients.
Blood Vessel Damage Could Explain Many Long COVID Symptoms
The researchers believe the hidden immune attacks may be contributing to damage involving the body’s microvasculature, the tiny blood vessels that supply oxygen and nutrients to organs and tissues.
This type of vascular dysfunction could explain why many long COVID patients experience chronic fatigue, dizziness, chest pain, shortness of breath, brain fog, palpitations, and neurological symptoms.
The study also supports growing evidence that SARS-CoV-2 infection can trigger persistent immune dysfunction long after the initial infection has ended. Instead of fully shutting down after fighting the virus, the immune system may continue attacking healthy tissues for months or even years.
Conclusions
The study provides compelling evidence that long COVID may involve hidden immune damage that escapes detection through standard serological testing. The discovery of persistent tissue-specific autoantibodies targeting the heart, lungs, and blood vessels suggests that many patients may be suffering from ongoing immune-mediated injury even when conventional laboratory tests appear normal.
The researchers emphasized that more advanced diagnostic approaches are urgently needed to identify these abnormalities and better understand the long-term consequences of COVID-19 infections. They also believe future treatments may need to focus on controlling immune dysregulation and protecting blood vessels rather than simply managing symptoms. These findings may help explain why long COVID remains so difficult to diagnose and treat in many patients worldwide.
The study findings were published in the peer reviewed journal: GeroScience.
https://link.springer.com/article/10.1007/s11357-026-02286-9
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