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The WHO has just released a formal definition of long COVID. Irina Efremova/Stocksy
  • Long COVID or post-COVID-19 are umbrella terms that refer to COVID-19 symptoms that persist beyond the initial phase of a SARS-CoV-2 infection.
  • The absence of a formal definition for post-COVID-19 has made the research of this condition and its management challenging.
  • The World Health Organization (WHO) recently published a definition of post-COVID-19 according to input from a panel of researchers, patients, and clinicians.
  • A standardized definition of post-COVID-19 will help advance research, facilitate awareness and acceptance, and aid diagnosis and management of this condition.

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Depending upon the severity of symptoms, most individuals recover from COVID-19 within the first 3–4 weeks after contracting the SARS-CoV-2 virus. Yet, a significant number of individuals experience lingering COVID-19 symptoms for weeks and months after this initial or acute phase of the infection.

People have collectively described these persistent COVID-19 symptoms with terms such as long COVID, “post-acute COVID-19,” or “post-COVID-19.”

Some of the common symptoms of long COVID include fatigue, breathing difficulties, insomnia, pain, and brain fog. Additionally, post-COVID-19 can adversely impact multiple organ systems, including the kidneys, lungs, pancreas, and heart.

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The lack of a standardized definition and consistent terminology for post-COVID-19 have been obstacles for researchers studying the condition and its clinical diagnosis and treatment.

The World Health Organization (WHO) recently published a clinical case definition of post-COVID-19 to address these issues. The WHO told Medical News Today, “This standardized clinical case definition will help clinicians to identify patients more easily and provide them the appropriate care, and it is crucial for advancing recognition and research.”

There was a lack of awareness and skepticism about post-COVID-19 among the public and medical professionals when the initial cases of long COVID emerged. Consequently, individuals with persistent symptoms did not get the necessary medical care they required.

Since then, researchers have conducted several studies to estimate the proportion of individuals with persistent symptoms and determine the risk factors and symptoms associated with post-COVID-19.

Although there is more widespread awareness about post-COVID-19 now, the absence of a formal definition for the condition has led to inconsistencies in protocols by research groups studying this condition.

For instance, there is a lack of consensus about the time of onset and duration of post-COVID-19 symptoms. This has led to research groups using different time windows to estimate the incidence of long COVID.

Similarly, the absence of consensus on the symptoms associated with long COVID has resulted in studies including or excluding certain symptoms, influencing the estimates of the incidence of the condition and its symptoms.

The lack of a formal clinical case definition, which can provide criteria for diagnosing long COVID, has created challenges for healthcare professionals to diagnose and treat individuals with persistent symptoms.

Several organizations and societies have issued definitions for post-COVID to facilitate research and help the management of individuals with long COVID. However, a globally standardized definition has been lacking.

The WHO used a protocol called the Delphi method to arrive at its definition of post-COVID. The Delphi method involves multiple rounds of surveying an expert panel to arrive at a consensus.

The WHO panel consisted of clinicians, researchers, patient groups and policy-makers, representing different nations. After two rounds of surveys and a panel discussion, the WHO panel decided on the term “post-COVID-19” and the following definition:

“Post-COVID-19 condition occurs in individuals with a history of probable or confirmed SARS-CoV-2 infection, usually 3 months from the onset of COVID-19 with symptoms that last for at least 2 months and cannot be explained by an alternative diagnosis.”

“Common symptoms include fatigue, shortness of breath, cognitive dysfunction but also others, which generally have an impact on everyday functioning. Symptoms may be new onset, following initial recovery from an acute COVID-19 episode, or persist from the initial illness. Symptoms may also fluctuate or relapse over time.”

Anxiety, depression, pain, and changes in hearing, smell, and taste were among the other symptoms that the definition included.

A salient feature of this definition of post-COVID-19 is that the WHO panel was more representative of the global community, comprising participants from middle and low income nations. Moreover, the WHO group included stakeholders, such as patient groups, whose opinions have often been overlooked while formulating previous definitions of post-COVID-19.

According to the WHO, “With a standardized definition, we hope to advance recognition of the condition. It will also help clinicians to identify patients more easily and provide them [with] the appropriate care. With this standardized definition, we will also be able to measure the burden of this illness better, giving us a better understanding of its prevalence globally. Finally, we hope it will aid and promote research on the topic. [Having] a single definition will allow us to synergize global research and advance a globally relevant understanding of the condition.”

The WHO also noted that it expects this definition to evolve as more researchers accumulate more data on the condition. Moreover, the panel highlighted that a separate definition might be necessary to describe the condition in children.

MNT spoke to Dr. Ziyad Al-Aly, who recently published a study characterizing the symptoms of post-COVID-19.

Dr. Al-Aly, the chief of Research and Development Service at the Veterans Affairs St. Louis Health Care System, said: “This definition is too little too late. I was hoping that the WHO definition would be more comprehensive and more inclusive. It does not move the field forward a single inch.”

Dr. Al-Aly noted that the WHO definition “is based on only symptomatology — ignoring a lot of the manifestations caused by COVID-19, including new-onset diabetes, heart disease, kidney disease. [Moreover,] it also conditions the diagnosis on the idea that symptoms cannot be explained by an alternative diagnosis.”

“[This] makes long COVID a diagnosis of exclusion — further marginalizing long COVID. I worry that this myopic definition of long COVID may be used by governments and health insurers to debase long COVID, deny insurance coverage, etc.”

Dr. Al-Aly also cautioned that gaslighters may exploit the shortcomings of this definition.

The WHO’s definition of post-COVID-19 differs from those that a few other agencies issued, such as the time of onset of the condition. For instance, the Centers for Disease Control and Prevention (CDC) use the term “post-COVID conditions” to describe symptoms of COVID-19 that persist beyond the acute phase of 4 or more weeks.

Asked about this discrepancy, Dr. Al-Aly noted that these inconsistencies in defining the condition might lead to differences in research methodologies unfortunately persisting.

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