MDBriefCase will be unavailable due to maintenance from Sunday, January 14 11PM to Monday, January 15 1AM ET.


The Prolonged Pandemic: What We Know about Long COVID

An estimated 10-40 percent of patients worldwide report experiencing persistent health issues associated with COVID for weeks, months, or even years after recovering from their infection. The condition – commonly called Long COVID – has caused much discussion and debate in healthcare communities worldwide as clinicians and health organizations attempt to determine what constitutes Long COVID, what causes it, and how best to diagnose and treat it.

The official definition of Long COVID is still in flux. Some clinicians consider it symptoms lasting four weeks or more, while others believe symptoms should last three months or longer. We do know that Long COVID can occur in anyone, even otherwise healthy people and those who experienced mild symptoms during their initial COVID infection. All variants of the virus appear to cause Long COVID, though studies have found the occurrence of Long COVID increased slightly as we went from the ‘wild-type’ virus to the Alpha variant. From there, researchers noticed a drop as Delta became the dominant strain (also around the time vaccines became available). Omicron and its descendant, the BA1.12.1 variant appear to cause Long COVID at half the rate of delta, and are not causing the same number of hospitalizations and deaths as earlier variants.

Symptoms of Long COVID

Long COVID can include a wide variety of symptoms that differ from patient to patient, though the most prevalent symptoms are fatigue, dyspnea (or shortness of breath), and brain fog. Many patients report feeling drained, with fatigue increasing dramatically after attempting to perform even simple tasks.

Other commonly reported symptoms include:

  • Depression, anxiety
  • Loss of smell
  • Dizziness
  • Coughing
  • Hair loss
  • Headaches
  • Heart palpitations or fluctuations in heart rate (racing, then normalizing)
  • Stomach pain
  • Diarrhea
  • Body and joint aches
  • Skin rashes
  • Swollen lymph nodes
  • Sleep disturbances
  • Tingling sensation

What Causes Long COVID?

It’s the million-dollar question: What causes Long COVID? Though there is no definitive answer, there are several strong hypotheses with solid data supporting each theory. Dr. David Strain shared three theories in a recent MDBriefCase webinar, The Other Pandemic – The Impact of Long COVID on Patients.

1. Persistent Viral Load

Much like Shingles, the COVID virus appears able to remain hidden in our bodies – some preferred locations being brain tissue and elsewhere in the nervous system. Studies have also discovered the virus can linger for months within the gut. It’s believed that patients experience local inflammation where the virus hides, e.g. brain tissue, which causes Long COVID symptoms like brain fog and fatigue. It’s also possible that the virus is occasionally releasing into the system – not at levels that would make a person infectious – but enough to cause small blood clots which cause many common Long COVID symptoms.

2. Blood Clots

Patients who had acute COVID experienced a tremendous increase in blood clots – pulmonary embolisms, strokes, and heart attacks all increased during the first waves of the pandemic. As a result, it’s believed Long COVID patients could have an abundance of amyloid-based microclots that could impair blood flow to the lungs and restrict oxygen exchange, and therefore cause some of the breathing problems, cardiac inflammation, and other common symptoms patients experience.

3. Mitochondrial Dysfunction

The COVID virus enters the body through the angiotensin-converting enzyme 2 or ACE2 enzyme. In a healthy human, the ACE2 enzyme is one of the pathways that stimulates mitochondrial assembly. When that pathway is blocked, mitochondria are adversely affected, and because they are the power source of every cell, when they fail, every cell in our bodies starts to shrivel. The cells that were most impacted during the initial COVID infection could account for why different people get different symptoms, e.g. tingling, rashes, hair loss, brain fog, fatigue.

This theory could also explain why fatigue is occurring in otherwise healthy people who experienced mild symptoms during their initial infection. Humans normally burn two types of fuel for energy:

  • Glucose (short term, does not need oxygen, generates lactate)
  • Fatty acids (uses oxygen, used more for long-term energy)

It’s believed that the virus ‘flips a switch,’ so patients are mainly burning glucose for energy instead of fatty acids. This process generates a lot of lactic acid, which is why patients run out of fuel quickly with minimal exertion.

Remember, these are only theories. There is still much research to be done to truly understand Long COVID, however, one thing is certain: there is no one-size-fits-all with the virus. As we learn more about Long COVID, it’s entirely possible we might discover it’s not one single condition, but one of three or more conditions requiring different approaches to care.

Diagnosing Patients

Because there are so many symptoms and unknowns surrounding Long COVID, it can be quite difficult to diagnose. Patients are also unlikely to make an appointment saying they have Long COVID – rather they will explain they are experiencing many of the symptoms associated with Long COVID. It’s up to clinicians to make the connection and determine if the patient previously had COVID and determine the best course of action from there.

Learn more about Long COVID, its symptoms, possible causes and treatments in this MDBriefCase webinar, The Other Pandemic – The Impact of Long COVID on Patients. The webinar features insights from a panel of COVID-19 experts, including Dr. Peter Lin, Dr. David Strain, and Dr. Vivien Brown.

Healthcare providers: Stay current on the latest COVID-19 updates and treatment best practices. Watch theStraight Talk on COVID-19 series for free on MDBriefCase. Join today.

MDBriefCase is a member of the Think Research family of companies.

+     +     +

Related: Discover how Order Sets can help hospitals and healthcare providers effectively manage COVID-19.

Author Agreement

In submitting your work (the “Work”) for potential posting on the MDBriefCase Healthcare Leadership Lab website (the “Website”), you (“You”) expressly agree to the following:

Review: MDBriefCase is pleased to consider the publication of Your Work on the Website.   The suitability of the Work for posting shall be determined by MDBRiefCase at its sole discretion. Nothing herein shall obligate MDBriefcase to post or otherwise publish the Work, or the maintain its posting in future.   

Editing; Identification: MDBriefcase shall have the right to edit the Work to conform to our standards of style, technological requirements, language usage, grammar and punctuation, provided that the meaning of the Work is not materially altered.  If posted, You will be identified as the author of the Work, or co-author if applicable.  

Grant of Rights:  As a condition of publication and for no monetary compensation, You hereby grant to MDBriefCase the following rights to the Work in any and all media whether now existing or hereafter developed, including print and electronic/digital formats:  (1) the exclusive right of first publication worldwide;  (2) the perpetual non-exclusive worldwide right to publish, reproduce, distribute, sell, adapt, perform, display, sublicense, and create derivative works, alone or in conjunction with other materials; (3) the perpetual non-exclusive worldwide right to use the Work, or any part thereof, in any other publication produced by MDBriefCase and/or on MDBriefCase’s website; and (4) the perpetual non-exclusive worldwide right to use the Work to promote and publicize MDBriefCase or its publications.  The grant of rights survives termination or expiration of this Agreement.    

Warranty:  You warrant that the Work is original with You and that it is not subject to any third party copyright; that You have authority to grant the rights in this Agreement; that publication of the Work will not libel anyone or infringe on or invade the rights of others; that You have full power and authority to enter into this Agreement; that the Work has not been published elsewhere in whole or in part; and that You have obtained permission from the copyright owner consistent with this Agreement for any third party copyrighted material in the Work.  This warranty survives termination or expiration of this Agreement.

Submission Agreement

Thank you for your interest in writing an article for the MDBriefCase Healthcare Leadership Lab website.

Audience and Appropriate Topics

The  Healthcare Leadership Lab welcomes submissions on all topics relevant to leaders in healthcare. Our topics include Leading in Healthcare, Leadership Lessons from COVID-19 and others. We prioritize stories that provide leadership advice to executives and managers in healthcare companies, offer actionable strategies for executing successful projects, and provide interesting angles on current healthcare topics. Submissions must be original work of the authors and unpublished.  When submitting, authors represent that they have included no material that is in violation of the rights of any other person or entity.


Articles must be educational and non-promotional. If they mention the author’s company or any of the company’s products or services by name within the text, such mention should be very limited and used for reference only, not for promotion. (For example, an author might cite a survey conducted by his company but not describe his company’s product as a solution to a business problem.) Articles will be edited for clarity, style and brevity. The final headline is determined by the editor.

Length of Submissions

Guest articles for the MDBriefCase Healthcare Leadership Lab may run between 500 and 1000 words. 


MDBriefCase reserves the right to accept or reject any submission  and the right to condition acceptance upon revision of material to conform to its criteria.   

No Compensation

There is no payment for contributed articles. However, MDBriefCase will give the author a byline. Authors are invited to link to the article on personal  websites, corporate websites and social media platforms.

Author Agreements

Each author understands and agrees that any submission accepted for posting is provided subject to MDBriefCase’s Author Agreement