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What is Long COVID?

“Long COVID,” is also known as “long-haul COVID” or “post-COVID condition.” The World Health Organization (WHO) defines long COVID as the onset or persistence of symptoms related to an acute COVID infection, occurring at least three months after the COVID infection and enduring at least two months.

Symptoms of Long COVID

Symptoms are varied but often are of three types: 1) neurological, 2) respiratory, and 3) cardiovascular.

Neurological symptoms in long COVID cases are thought to be the effect of neuroinflammation. Many involve loss of smell, headache, and trouble sleeping. However, the most common symptom is fatigue, involving one-third of cases. The next most common symptom is cognitive impairment involving one-fifth of cases.1

Cognitive impairment typically presents itself as “brain fog,” a combination of slow thinking and difficulty remembering, especially a matter of “finding the right word.” This phenomenon of “not finding the right word” is called anomia and is important because it can be measured in neuropsychological tests. These tests show both a decrease in the number of correct answers and an increase in reaction time among patients so affected.2

Neurological complications are not newly discovered consequences of viral infection. Two such complications come to mind, both identified in the early 20th century.

First was Guillain–Barré syndrome, first described in 1859 by Jean-Baptiste Octave Landry and identified more precisely in 1916 by Georges Guillain, Jean Alexandre Barré, and André Strohl. It is a rapid-onset ascending weakness sometimes following a viral, or less frequently bacterial, infection.

Second was von Economo encephalitis or encephalitis lethargica, a sleeping sickness seen subsequent to the 1918 Spanish Flu epidemic and described by Constantin von Economo and Jean-Rene Cruche. The treatment of some of the victims of this encephalitis was the subject of the 1990 film Awakenings with Robin Williams and Robert DeNiro.3

Respiratory symptoms

Shortness of breath and symptoms of chronic lung disease. Air trapping often results from inflammation, edema, or fibrosis. Incidence of air trapping was 25.4% in ambulatory COVID patients compared to 7.2 % in healthy controls. It was still present in 8 of the 9 patients who underwent imaging more than 200 days post-diagnosis. Fibrosis was most common in patients admitted to the ICU.4

Shortness of breath, or dyspnea, is the most prominent respiratory symptom of COVID. It frequently results from air trapping. Air trapping, in turn, can be caused by inflammation, edema or airways swelling, or by fibrosis. All three of these can constrict the airways, which, for technical reasons, is worse on expiration than inspiration. Air trapped in the lungs impedes air entering the lungs, hence the shortness of breath.

Air trapping is prominent in COVID, affecting even COVID patients not confined to bed. In fact, 25.4% of such patients evidenced air trapping compared to 7.2% of healthy controls. Moreover, and relevant to long COVID, the air trapping was still present in 8 of the 9 patients in one sample who underwent testing at least 200 days after their original COVID diagnosis.4 Interestingly, although long COVID can occur even after asymptomatic or mild COVID-195, the most enduring complication of fibrosis was most common in patients admitted to the ICU.4

Cardiovascular symptoms

Cardiovascular symptoms of long COVID include tachycardia, exercise intolerance, chest pain, and shortness of breath.6 These can result from an inflammation of the heart muscle called myocarditis, which sometimes follows viral infections.

While myocarditis can sometimes follow COVID mRNA vaccination, the fact remains that myocarditis after COVID infection is six times more common than myocarditis after vaccination.7 Even then, the incidence of myocarditis after vaccination in the most vulnerable group, males aged 12-29, is only 0.0004%. For older males and for females, the incidence is only 1/20th the aforementioned rate6. Consequently, myocarditis risk from the mRNA vaccines, Pfizer and Moderna, is minimal and certainly much less than its risk from catching COVID.

Causes of Long COVID

The causes of long COVID are unclear. A leading theory, adopted from our knowledge of Guillain–Barré syndrome, is that an immune reaction instigated by the virus causes the condition. Another theory is that a reservoir of the corona virus remains in the body to reactivate later. Yet another theory proposes that corona virus remnants trigger chronic inflammation8. In short, the causes are uncertain.

Frequency of Long COVID

The frequency of long COVID is difficult to determine accurately since some symptoms are hard to verify or possibly related to other causes. Nevertheless, the consensus is that 10-30% of those initially infected with corona will develop long COVID6.

Notably, people who'd had COVID were 25% more likely to develop dysrhythmias, 20% more likely to develop diabetes, 60% more likely to develop fatigue, 21% more likely to develop genitourinary conditions, 39% more likely to develop chest pains, and a full 3.88 times more likely to develop trouble with olfaction.9

Finally, for an estimated 37% who contract the virus, symptoms can linger for weeks, months, or even years10.

How Long Will Long COVID Last?

Certainly, more evidence is needed, but it seems at present that most people with long COVID will recover with time. However, such serious chronic diseases as Type 2 diabetes and pre-existing pulmonary disease could adversely affect recovery11. Finally, it seems that loss of smell can last for months to years.12

Anticipating and Identifying Long COVID

In one study, researchers identified four early things linked to greater chances that someone with COVID-19 will have long-term effects: type 2 diabetes at the time of diagnosis, the presence of specific autoantibodies, unusual levels of SARS-CoV-2 RNA in the blood, and signs of the Epstein-Barr virus in the blood.11

In another study, from Yale University, the researchers tasked dogs with identifying 45 people with long COVID versus 188 people without it. The dogs were accurate more than 50% of the time in identifying long COVID8.

Perhaps, learning how the dogs were able to do this can form the basis for a clinical laboratory test.

Vaccination as Long COVID Treatment and Prevention

Empirically, vaccination seems to alleviate long COVID symptoms in some people12,11,13. This is consistent with the theory that corona virus remains in the body in some form after COVID infecton8.

A second infection with COVID is less likely but possible. Although there is scant information regarding the probabilities of long COVID after a second versus a first corona infection, it seems there is some probability of occurrence. Consequently, vaccination of a previously unvaccinated COVID recoveree, can reduce the chance of a second infection with consequent long COVID.

Finally, the optimum way to approach a problem is not to have it. The optimum way to avoid long COVID is to avoid a COVID infection I the first place. Again … vaccination!


In brief, long COVID can extend for an extended period, even years, after the acute infection is over. Its symptoms can affect any area of the body, but most commonly involve the nervous, respiratory, and cardiovascular systems. Causes are unknown but may involve an immune response triggered by the COVID infection. Long COVID may affect one-third of those recovering from the corona infection. Patients with Type 2 diabetes or pre-existing pulmonary disease may be more susceptible to long COVID. Lastly, vaccination seems to alleviate long COVID symptoms.


The conclusion is simple. Long COVID is real and is troublesome. The optimal way to address a problem is not to have it. The optimal way to avoid long COVID is to avoid an initial COVID infection. To avoid an initial COVID infection … get vaccinated.

Thomas Falasca, DO


1 Lui, L. (2022, February 3). Cognitive impairment in long covid. Medscape. Retrieved March 23, 2022, from

2 George, J. (2022, February 3). Memory, Concentration Problems Plague 70% of Long COVID Patients | MedPage Today. MedPage Today. Retrieved March 19, 2022, from

3 Hoffman, L. A., & Vilensky, J. A. (2017). Encephalitis lethargica: 100 years after the epidemic. Brain, 140(8), 2246–2251.

4 Alexander, W. (2022, March 16). Air trapping: Common in patients with Long Covid. Medscape. Retrieved March 23, 2022, from

5 McNamara, D. (2022, February 4). Q&A: Long covid symptoms, management, and where we're headed. WebMD. Retrieved March 23, 2022, from

6 ACC issues clinical guidance on cardiovascular consequences of covid-19. American College of Cardiology. (2022, March 16). Retrieved March 23, 2022, from

7 Wilson, C. (2021). Myocarditis more likely after infection than vaccination. New Scientist, 251(3346), 14.

8 McNamara, D. (2022, February 8). Promising leads to crack long covid discovered. WebMD. Retrieved March 23, 2022, from

9 McNamara, D. (2022, January 28). Long covid is real, and many real questions remain. WebMD. Retrieved March 23, 2022, from

10 Kalter, L. (2022, February 10). Scientists see hope in new therapy for Covid Brain Fog Patients. WebMD. Retrieved March 23, 2022, from

11 McNamara, D. (2022, January 28). Long covid is real, and many real questions remain. WebMD. Retrieved March 23, 2022, from

12 Watto, M., Williams, P. N., The Curbsiders, J. 2022, The Curbsiders, N. 2021, The Curbsiders, O. 2021, The Curbsiders, S. 2021, & The Curbsiders, A. 2021. (2022, March 8). Long COVID: Learning as We Go. The Curbsiders. Retrieved March 20, 2022, from

13 Crist, C. (2022, February 16). Vaccination reduces chance of getting long covid, studies say. WebMD. Retrieved March 20, 2022, from

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