What is Long COVID?

Long COVID refers to persistent symptoms lasting longer than a month after recovering from acute infection by SARS-CoV-2. It is classified as a post-infectious syndrome with different subtypes. Fatigue is the most common symptom of Long COVID.

CONTENTS:

• Do You Have Long COVID
• What Is Long COVID, and What Does It Mean?
• Is Long COVID a Disease, a Condition, or a Syndrome?
• Main Symptoms of Long COVID
• Do I Have Long COVID or Something Else?
• Summary
• Selected References

Is Long COVID a Disease, a Condition, or a Syndrome?

A syndrome is a recognizable complex of symptoms and clinical findings associated with a particular disease or disorder, including examination findings and laboratory test results. Long COVID is classified as a post-COVID syndrome with four major subtypes, each having symptoms and universal findings.

SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) is the communicable infectious disease responsible for the COVID-19 pandemic. The research remains unsure of what causes Long COVID. Is it from lingering SARS-CoV-2 viruses, reactivation of EBV, or an immunological disruption that doesn’t return to normal after infection?

What Are the Four Subtypes of Long COVID?

While there are no specific subtypes, researchers gathered information from over 20,000 COVID patients and analyzed them using a computer-based program for common diagnoses. They narrowed down over 200 Long COVID symptoms into four common categories: neurological, cardiopulmonary, respiratory, and gastrointestinal.

A study published in Nature Medicine used machine learning to categorize PASC into patterns and grouped them into four clusters. The study aimed to define these four groups to help healthcare providers better serve patients during the early and mid-stages of illness.

Cluster 1 – Heart and Kidney: These patients primarily exhibited cardiac and renal-related symptoms, such as renal failure, anemia, and electrolyte imbalances. This group had an average age of 65, with a majority being men and experiencing more severe illness. They also took more prescription medications than the other groups.

Cluster 2 – Respiratory, Sleep, and Anxiety: This group primarily experienced respiratory symptoms, including acute upper respiratory symptoms and chronic lung disease. The average age was 51, and they were primarily women. They took anti-allergy medications, steroid inhalers, and anti-inflammatory drugs. Cluster 3 – Musculoskeletal and Nervous: The main symptoms in this group included musculoskeletal pain, headaches, and sleep disturbances. They were predominantly female, with an average age was 57, and had a higher usage of pain relievers compared to other groups.

Cluster 4 – Digestive and Respiratory: With an average age was 54, this cluster primarily consisted of women. Despite having the highest rate of emergency room visits, they had the lowest rate for ventilation usage and critical care. They had less underlying medical conditions and took more prescription drugs for the digestive system. Overall, they had the mildest acute symptoms.

Clusters of Symptoms Differ by Age

Another group of researchers organized symptoms into age-stratified clusters: a neurological cluster, a cardiopulmonary cluster, a respiratory cluster, a gastrointestinal cluster, and a comorbidity cluster.  

• Patients under 21 years of age: neurological cluster, respiratory cluster, cardiopulmonary cluster, and gastrointestinal cluster
• Patients 21-45 years of age: neurological cluster, cardiopulmonary cluster, and a comorbidity cluster
• Patients 48-65 years of age: cardiopulmonary, comorbidity, and neurological clusters
• Patients 66 years of age and older: a larger comorbidity cluster, plus cardiopulmonary and neurological clusters

Younger patients had fewer comorbidities, a condition when more than one disease occurs at the same time. The number and severity of comorbidities increased with age.

Main Symptoms of Long COVID

Long COVID symptoms are well-documented, with over 200 listed by the American Medical Association (AMA). The question is, which of these symptoms are the most important?

Persistent Fatigue Is Central to Long COVID

Fatigue is the most common and central symptom of Long COVID. Patients experience persistent exhaustion, impaired fitness, and post-exertional malaise, feeling tired without having done anything. If they do something, they tire easily and find recovery difficult. Even normal housework can be exhausting, taking several days to recover from. They may feel sleepy even during the daytime but don’t wake refreshed or feel better after a nap.

Impaired Fitness and Post-Exertional Malaise

Though not all Long COVID patients experience debilitating fatigue, impaired fitness is the most common symptom for those without severe fatigue. Many also suffer from post-exertional malaise after doing housework or mild exercise, leaving them bedridden for the rest of the day after just twenty minutes of mild activity around the house.

Brain Fog: Long COVID sufferers have “brain fog,” the sense of feeling mentally sluggish with fuzzy thinking. A Scientific American article calls for more attention to brain fog, a condition that includes mental confusion, concentration difficulty, forgetfulness, anxiety, and dull headaches.

Venous Insufficiency: Chronic venous insufficiency occurs when the veins in your legs are damaged or compromised. Leg symptoms are often worse when standing and are better when lying down. They feel heavy and may tingle, itch, and have rashes or discoloration.

Unexplained Achiness and Soreness: Chronic infection, including with SARS-CoV-2, is associated with the activation of inflammatory genes and the persistence of proinflammatory cytokines like cytotoxic CD8+ T-lymphocytes.

Changes in Heart Rate: 14% of Long COVID patients have elevated heart rates for months after initial infection.

Episodic and Relapsing: You start to get better. One day, you wake up feeling like your former self. You want to go for a run or hit the gym. You prepare a full breakfast and organize your closet. For the moment, you feel like your old self again. You get your gym bag ready, but as you head for the door, it feels as if it’s a hundred miles away. When you reach for the door handle, you’re so weak you can barely turn it. This is known as an exacerbation due to activity, and it’s not uncommon in ME/CFS and Long COVID. Patients often develop an aversion to trying anything new; some can’t even do normal housework because of exacerbating symptoms.

Do I Have Long COVID or Something Else?

Since there is no definitive laboratory test and so many symptoms, a diagnosis is made based on a confirmed history of SARS-CoV-2 infection, your general presentation, test results at a clinic or private physician’s office, and a specific set of symptoms.

You don’t want to be labeled as having Long COVID just because you experience exasperating symptoms. Here are some questions to ask yourself:

• Have you had the same symptoms before the pandemic?
• Were you diagnosed with a chronic condition like multiple sclerosis, rheumatoid arthritis, or ME/CFS before the pandemic?
• Did you have symptoms of acute COVID during the pandemic?
• Did you have a positive rapid antigen test?
• Did you get another laboratory test?
• Do you have the symptom profile, especially the cardinal ones like lack of taste and smell?
• Have your symptoms persisted for more than four weeks? More than six months?

12 Hallmark Symptoms Doctors Use to Diagnose Long COVID 

The JAMA study identified twelve symptoms in Long COVID patients six months after initial infection. Think of these as hallmarks of Long COVID. You don’t have to have them all, but if you have at least six, you likely have Long COVID.

1. Persistent fatigue
2. Post-exertional malaise (fatigue exacerbated by even minor physical activity)
3. Disruption of smell and taste
4. Chronic cough
5. Brain fog
6. Thirst
7. Palpitations
8. Chest pain
9. Diminished or absence of sexual desire
10. Dizziness/light-headedness
11. Gastrointestinal symptoms, including abdominal pain and diarrhea
12. Abnormal movements, including tremors

If you answer yes to these questions, you likely have Long COVID. Otherwise, you could have a different condition with symptoms that overlap or mimic Long COVID, like an autoimmune disorder. Not everyone fits into easily identifiable groups. Long COVID has a wide range of symptoms and many individual variations that span multiple organ systems. It’s best not to try to diagnose yourself. Seek a doctor knowledgeable in chronic viral infections, autonomic nervous system disorders, or experience in treating COVID for a diagnosis.