Identifying a Potential Biomarker for Long-Covid: Insights into Persistent Symptoms and Recovery Challenges

October 2, 2025

Blood Protein Shows Promise as Potential Biomarker for Long Covid

A potential biomarker for identifying long Covid has been identified in a blood protein.

Vienna, Austria – A newly identified blood protein, Pentraxin 3 (PTX-3), is showing important promise as a potential indicator for the advancement of Long Covid.Scientists at the Medical university of Vienna have discovered substantially elevated levels of PTX-3 in individuals who have recovered from severe Covid-19 infections, even several months after initial recovery. This breakthrough research could pave the way for earlier detection and a better understanding of the prolonged health challenges associated with the virus.

The Research Findings

The study, published in the peer-reviewed journal “Frontiers in Immunology,” involved analyzing acute phase proteins in the blood of 141 individuals who had previously contracted Covid-19. These levels were then compared to those of a control group of 98 people who had not been infected. Acute phase proteins are integral to the innate immune system, quickly released during infection to combat illness and regulate inflammatory responses.

Researchers found that while many acute phase proteins typically return to normal levels shortly after an infection subsides, PTX-3 levels remained substantially higher in patients who experienced severe Covid-19, both ten weeks and ten months post-infection. This sustained elevation suggests a prolonged immune response or ongoing tissue damage.

PTX-3 and Myalgic Encephalomyelitis/Chronic fatigue Syndrome

Interestingly,elevated PTX-3 levels were also associated with an increased likelihood of developing Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS),a debilitating condition often linked to chronic infections. According to the CDC, approximately 1.5 to 2.5 million americans are estimated to have ME/CFS, highlighting the potential significance of this finding.

“We beleive that the persistent elevation of PTX-3 might indicate ongoing repair mechanisms within the body or even the continued presence of SARS-CoV-2 remnants,” explained Winfried Pickl, a lead researcher on the project. Rudolf Valenta added, “PTX-3 could thus serve as a crucial biomarker for identifying long-lasting tissue damage, persistent immune activation, and potential complications following Covid-19.”

Did You Know? Recent data from the World Health Organization estimates that at least 10% of confirmed Covid-19 cases experience symptoms for a duration of three months or longer, qualifying as Long Covid.

Protein	Typical Behavior After Infection	Observation in Severe covid Survivors
Acute Phase Proteins (General)	Return to baseline levels within days	Variable; some return to normal
Pentraxin 3 (PTX-3)	Typically returns to baseline levels	Remains significantly elevated for months

Further examination is currently underway to fully understand the role of PTX-3 in the pathogenesis of Long Covid and ME/CFS. Researchers hope that this discovery will lead to improved diagnostic tools and possibly targeted therapies for those suffering from these conditions.

understanding Biomarkers and Long Covid

A biomarker is a measurable indicator of a biological state or condition. In the context of Long Covid, identifying reliable biomarkers is crucial for early diagnosis, predicting disease progression, and developing effective treatments. Long Covid, also known as post-acute sequelae of SARS-CoV-2 infection (PASC), encompasses a wide range of symptoms that can persist for weeks, months, or even years after the initial infection. Common symptoms include fatigue, shortness of breath, cognitive dysfunction (“brain fog”), and chronic pain.

Pro Tip: Maintaining a healthy lifestyle, including regular exercise, a balanced diet, and sufficient sleep, may help mitigate some of the long-term effects of Covid-19, but it is not a substitute for medical care.

Frequently Asked Questions About Long Covid and PTX-3

• What is Long Covid? Long Covid refers to a range of symptoms that persist for weeks or months after the initial Covid-19 infection has subsided.
• What is Pentraxin 3 (PTX-3)? PTX-3 is a protein involved in the body’s immune response and tissue repair processes.
• How does PTX-3 relate to Long Covid? Elevated levels of PTX-3 have been observed in individuals with Long Covid, suggesting it may be a biomarker for the condition.
• Can PTX-3 levels predict the severity of Long Covid? Research is ongoing to determine whether PTX-3 levels can accurately predict the severity and progression of Long Covid.
• Is there a cure for Long Covid? Currently, there is no cure for Long Covid, but treatments are available to manage symptoms and improve quality of life.
• what are the common symptoms of Long Covid? Common symptoms include fatigue, shortness of breath, brain fog, chest pain, and loss of taste or smell.
• Where can I find more information about Long Covid? Visit the CDC’s website on Long Covid for the latest updates and resources.

What are your thoughts on this new potential biomarker? Do you or someone you know struggle with the lasting effects of Covid-19? Share your experiences in the comments below!

What specific types of autoantibodies are currently being investigated as potential biomarkers for Long-Covid, and what symptoms are they correlated with?

Understanding the Complexities of Long-Covid

Long-Covid, also known as Post-Acute Sequelae of SARS-CoV-2 infection (PASC), presents a significant global health challenge. Characterized by persistent symptoms weeks or months after the initial acute infection, it impacts individuals across all age groups and severity levels of the original COVID-19 illness. Identifying reliable Long-Covid biomarkers is crucial for accurate diagnosis, personalized treatment strategies, and predicting recovery trajectories. Current research focuses on a multifaceted approach, recognizing that Long-Covid isn’t a single disease but a syndrome with diverse presentations. Key symptoms include fatigue,brain fog,shortness of breath,chest pain,and neurological issues. Understanding the underlying biological mechanisms driving these symptoms is paramount.

the Search for Measurable Indicators: Current Biomarker Candidates

Several potential biomarkers are under investigation, each offering a piece of the puzzle. These aren’t definitive yet, but represent promising avenues for research.

* Autoantibodies: A growing body of evidence suggests the presence of autoantibodies – antibodies that mistakenly attack the body’s own tissues – in a significant proportion of Long-Covid patients. These autoantibodies target various organs and systems, potentially contributing to inflammation and dysfunction. Specific autoantibodies against interferon receptors have been linked to fatigue and cognitive impairment.

* Inflammatory Markers: While initial acute COVID-19 is marked by a cytokine storm, long-Covid often presents with more subtle, chronic inflammation. Researchers are examining levels of:

* C-reactive protein (CRP): A general marker of inflammation.

* Interleukin-6 (IL-6): A pro-inflammatory cytokine implicated in various chronic diseases.

* Tumor Necrosis Factor-alpha (TNF-α): Another key inflammatory mediator.

* Microclots & Endothelial Dysfunction: Emerging research points to the formation of microclots – tiny blood clots – in the capillaries of Long-Covid patients. These microclots can impair oxygen delivery to tissues,contributing to fatigue and cognitive dysfunction. Biomarkers related to endothelial dysfunction (the lining of blood vessels) are also being investigated,including:

* Von Willebrand factor (vWF): Involved in blood clotting.

* D-dimer: A marker of blood clot breakdown.

* Metabolomic Signatures: Metabolomics, the study of small molecules in the body, is revealing distinct metabolic profiles in Long-Covid patients. Alterations in amino acid metabolism, lipid metabolism, and energy production pathways are frequently observed.These changes could serve as diagnostic biomarkers and potential therapeutic targets.

* gut Microbiome Dysbiosis: The gut microbiome plays a critical role in immune function and overall health.Long-Covid is often associated with gut dysbiosis – an imbalance in the gut microbial community. Analyzing the composition of the gut microbiome could identify specific bacterial signatures linked to Long-Covid symptoms.

The Role of Persistent viral Reservoirs

One hypothesis suggests that fragments of the SARS-CoV-2 virus may persist in certain tissues, triggering ongoing immune activation and inflammation. Identifying these viral reservoirs and developing methods to detect them is a key area of research.

* Viral RNA Detection: Researchers are using highly sensitive PCR techniques to detect low levels of viral RNA in tissues like the gut, brain, and lymph nodes.

* Viral Protein Detection: Identifying viral proteins within tissues provides further evidence of persistent infection.

* Immune Response to Viral Fragments: Analyzing the immune response to specific viral proteins can reveal whether the immune system is still actively fighting the virus.

challenges in biomarker Identification & Validation

Identifying reliable Long-Covid biomarkers is a complex undertaking. Several challenges need to be addressed:

1. Heterogeneity of Long-Covid: The wide range of symptoms and underlying mechanisms makes it difficult to find a single biomarker that applies to all patients.
2. Lack of Standardized Definitions: Inconsistent definitions of Long-Covid across studies hinder data comparison and biomarker validation.
3. Confounding Factors: Pre-existing conditions, lifestyle factors, and vaccination status can influence biomarker levels, making it challenging to isolate the effects of Long-covid.
4. Longitudinal Studies: Long-term longitudinal studies are needed to track biomarker changes over time and correlate them with symptom severity and recovery.

Advanced Technologies & Future Directions in Biomarker Discovery

Several cutting-edge technologies are accelerating the search for Long-Covid biomarkers:

* Proteomics: Analyzing the entire protein content of biological samples to identify proteins that are differentially expressed in Long-Covid patients.

* Single-Cell RNA Sequencing: Examining gene expression at the single-cell level to identify specific cell types that are affected by Long-Covid.

* Artificial Intelligence (AI) & Machine Learning: Using AI algorithms to analyze large datasets of clinical and biomarker data to identify patterns and predict outcomes.

* Multi-Omics Integration: Combining data from genomics, proteomics, metabolomics, and other “omics” technologies to gain a more complete understanding of the disease.

Real-World example: The RECOVER Initiative

The National Institutes of Health (NIH) launched the RECOVER Initiative, a large-scale research program dedicated to