The long COVID syndrome—also known as post-COVID-19 condition or long-haul COVID—has become one of the major medical challenges following the coronavirus pandemic.
It affects patients who, after overcoming the acute phase of the SARS-CoV-2 infection, continue to experience lingering symptoms that significantly impact their quality of life and functional capacity.
Understanding what lies behind long COVID and how to modulate the immune response effectively is key to recovery.
What is Long COVID and How Does It Manifest?
Long COVID refers to symptoms that persist for more than 12 weeks after the acute coronavirus infection has resolved, without any other medical explanation.
It’s not just about “feeling tired for a few extra days.” In many cases, these symptoms significantly affect energy levels, muscle strength, focus, or breathing, and can interfere with daily activities, work, or rest.
Symptoms vary from person to person, but some are especially common:
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Severe and persistent fatigue that does not improve with rest
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Shortness of breath or difficulty breathing
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Brain fog: trouble focusing, thinking clearly, or remembering things
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Muscle or joint pain
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Rapid heartbeat or palpitations
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Sleep disturbances or anxiety
These symptoms may appear intermittently or worsen after physical or mental exertion.
Importantly, long COVID is not limited to patients who had severe illness. It has also been documented in moderate and even mild cases.
It is estimated that between 10% and 20% of people who contract COVID-19 may experience prolonged symptoms, with great clinical variability and a wide range of durations.
What Happens to the Immune System After a COVID-19 Infection?
When SARS-CoV-2 enters the body, the immune system activates to eliminate it. Under normal circumstances, once the infection is controlled, the immune system should return to its baseline state. But in some cases, this doesn’t happen. Instead, the body remains in a kind of “inflammatory mode” that disrupts immune balance.
Why Do Symptoms Last So Long?
One of the main reasons involves the immune system. Even though the virus is no longer active, some people’s immune defenses don’t return to their normal state. It’s as if the body remains “on high alert,” producing low-grade inflammation that continues to drive symptoms. In other words: the immune system keeps fighting, even though the virus is gone.
This imbalance can be seen in a reduction of NK (Natural Killer) cells—crucial for clearing viral remnants and preventing reactivations—a dysregulated cytokine response, which causes persistent or ineffective inflammation, and immune fatigue, where the system becomes less responsive to new threats.
This disruption helps explain why some people continue to feel unwell long after the infection has resolved.
How to Support the Immune System During Recovery
After a period of stress or prolonged illness, like a viral infection, it’s normal for the body to need time to regain balance. In these cases, prioritizing rest, proper nutrition, and stress management is essential. There are also natural ingredients that have been studied for their ability to support normal immune function.
One of them is fermented rice arabinoxylan, a compound found in supplements like Bi·Bran®, often used by individuals focused on immune health.
If you still feel like you haven’t regained your energy after COVID, or if your body isn’t responding the way it used to, your immune system might still be out of balance. We recommend consulting a healthcare professional for guidance.
