COVID-19’s lingering impact on biomarkers revealed in massive study

Medical News: COVID-19 has had a profound impact on public health, with millions of cases worldwide. While many patients recover within weeks, some continue to experience symptoms for months, known as long COVID. A groundbreaking study by researchers from Ben-Gurion University of the Negev and Clalit Research Institute in Israel now sheds light on how SARS-CoV-2 infection affects common biomarkers long after the initial infection.

 COVID-19’s lingering impact on biomarkers revealed in massive study

This Medical News report uncovers how COVID-19 impacts lab results, using data from over 360,000 patients who contracted the virus, comparing them with an equal number of matched controls who did not. This study is one of the largest of its kind, providing valuable insight into the long-term changes in the body caused by COVID-19, particularly in the immune system.
 
Long-Term Effects on Laboratory Biomarkers
The research team, led by Dr Tomer David Meirman, Dr Bracha Shapira, Dr Ran D. Balicer, Dr Lior Rokach, and Dr Noa Dagan, investigated 63 common biomarkers. They analyzed over 26 million lab results over a 12-month period, comparing data from COVID-19-positive individuals with those who had never contracted the virus.
 
Interestingly, while most biomarker changes returned to normal within 1 to 4 months post-infection, certain long-lasting effects persisted, especially in the immune system. These findings were consistent in both vaccinated and unvaccinated individuals, although some biomarkers showed milder changes in vaccinated individuals.
 
Immune System Alterations
Among the key findings, the most significant impact was on white blood cell (WBC) counts, which took 7 to 8 months to return to normal. WBCs, which are critical to our body’s defense against infections, particularly saw reductions in neutrophils, monocytes, and basophils - key players in our immune response.

The decrease in WBCs is concerning because it may leave individuals more susceptible to other infections after recovering from COVID-19. Neutrophils and monocytes, part of the body’s first line of defense, play essential roles in fighting infections. Their prolonged reduction could explain why some COVID-19 survivors experience persistent fatigue and recurrent infections.
 
Electrolyte Imbalance: Potassium Levels Drop
Another significant finding was a drop in potassium levels that lasted for up to 5 months. Potassium is crucial for muscle function, nerve signaling, and maintaining proper heart rhythm. Low potassium levels could contribute to symptoms like muscle weakness, fatigue, and even heart problems, all of which are common in long COVID patients.
 
Although the decrease in potassium was relatively small on average, for some individuals, it might have been more pronounced, especially in those who reported severe long COVID symptoms. This subtle yet prolonged drop in potassium is consistent with previous findings that have linked COVID-19 with acute and sometimes pro longed electrolyte imbalances.
 
Red Blood Cells and Hemoglobin Changes
COVID-19 also impacted red blood cells (RBCs) and hemoglobin. Hemoglobin and hematocrit levels, key indicators of oxygen transport in the blood, decreased for the first three months post-infection, which the study associates with anemia of inflammation or chronic disease. This type of anemia is often seen in chronic infections and inflammatory conditions and could explain some of the persistent fatigue experienced by COVID-19 survivors.
 
Acute Phase Reactants: Inflammation and Healing
The study found expected changes in biomarkers that signal inflammation and healing, known as acute-phase reactants. C-reactive protein (CRP), ferritin, and erythrocyte sedimentation rate (ESR) - all markers of inflammation - spiked during the first month after infection. These levels gradually returned to normal after the second month, reflecting the body’s response to the virus and the subsequent healing process.
 
On the other hand, markers that tend to decrease during inflammation, like transferrin and albumin, dropped significantly during the acute phase but recovered after two to three months.
 
Infection Predisposition: Do Biomarkers Predict COVID-19?
Interestingly, the researchers also explored whether certain biomarkers could predict an individual’s susceptibility to COVID-19. By examining the biomarkers of the control group prior to infection, the study revealed some patterns that may hint at increased susceptibility. Individuals with slightly elevated levels of creatinine and urea - markers of kidney function - were more likely to develop COVID-19. Low levels of WBCs and platelets before infection were also associated with a higher likelihood of contracting the virus.
 
This discovery suggests that individuals with pre-existing subtle abnormalities in these biomarkers may be more vulnerable to the virus, although further research is needed to explore this connection.
 
What Does It All Mean?
The study provides robust evidence that while most laboratory abnormalities caused by COVID-19 resolve within a few months, some effects, particularly on the immune system and electrolytes like potassium, can persist for much longer. This extended impact may contribute to the wide range of symptoms reported by long COVID patients, including fatigue, muscle weakness, and recurrent infections.
 
Although many of these biomarker changes eventually return to normal, the prolonged alterations in WBC counts and potassium levels are concerning. They suggest that even after the acute phase of COVID-19 passes, the body continues to experience underlying changes that could affect overall health and recovery.
 
Conclusions: Looking Ahead
The findings from this study are crucial in understanding the long-term health impacts of COVID-19. By identifying which biomarkers are affected and for how long, this research opens the door to new diagnostic tools and treatments for long COVID patients. Doctors could potentially use these biomarkers to monitor recovery and tailor treatment plans based on the patient’s specific post-COVID-19 profile.
 
Moreover, the discovery that certain biomarkers might predict susceptibility to infection could lead to preventive strategies, especially for those at higher risk. Further research will be essential in confirming these findings and developing clinical interventions to address the lingering effects of COVID-19.

While most patients see a return to normal within a few months, the lasting changes in immune function and electrolyte balance remind us that COVID-19’s effects can extend well beyond the initial illness. As researchers continue to unravel the complexities of long COVID, this study provides a crucial piece of the puzzle.
 
The study findings were published in the peer-reviewed:  Journal of Infection.
https://www.sciencedirect.com/science/article/pii/S0163445324002524
 
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