WHO Releases First Official Long COVID Definition

Healthcare worker wearing a face mask.

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Key Takeaways

  • Long COVID has been used to refer to a range of new, returning, or ongoing symptoms after initial COVID-19 infection.
  • This month, the WHO has published an official definition of post-COVID-19 to advance research and help diagnose individuals.
  • The definition can change and be refined further as new evidence emerges regarding the condition.

Although most COVID-19 patients recover after their initial infection, about 10% to 20% experience new, returning, or lingering symptoms for weeks or months. Over the past year this condition has been called many names, including “long COVID” and “chronic COVID-19 syndrome.”

But until now, there was a lack of an official clinical definition that detailed the time of onset, duration, and types of symptoms. For over a year, medical professionals and researchers have struggled to diagnose patients and provide them with the right care.

To address the challenges brought by the absence of globally standardized terminology for the long-term effects of the condition, the World Health Organization (WHO) recently published an official definition.

They hope that defining post-COVID-19 will advance both the advocacy and research of the condition, as well as help improve the recognition and care of patients experiencing it.

How Is Long COVID Defined?

The WHO surveyed a panel consisting of patients, patient-researchers, medical experts, and WHO staff to arrive at a clinical case definition for post-COVID-19.

They define it as, a condition that “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.”

The definition states that common symptoms include:

  • Fatigue
  • Shortness of breath
  • Cognitive dysfunction
  • Others which generally have an impact on everyday functioning

These symptoms may be new “following initial recovery from an acute COVID-19 episode, or persist from the initial illness. Symptoms may also fluctuate or relapse over time.”

The definition highlights that post-COVID-19 may have an impact on everyday functioning, which health providers have observed when patients explain that they do not feel like their “normal selves,” Carl Lambert Jr., MD, family physician and assistant professor of family medicine at the Rush University Medical Center, tells Verywell.

There is no minimum number of symptoms required for the diagnosis, and the WHO noted that a separate definition may be applicable for children.

Why Is It Crucial to Establish a Standardized Definition?

Given that COVID-19 is a relatively new disease, its natural history and range of effects have yet to be understood.

However, the absence of a clinical case definition for its lingering symptoms has made it challenging for clinicians and policymakers to discuss and study the condition, as well as potentially manage its symptoms.

“There has been no consensus on a definition among physicians because this is new and we are still learning about individuals who present with recurrent, or clustered, or persistent or new symptoms,” Priya Duggal, PhD, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health who currently leads the Johns Hopkins COVID Long Study, tells Verywell.

The term “long COVID” was generally used to refer to a wide range of symptoms after initial COVID-19 infection, but the umbrella term encompassed different types and combinations of health problems for varying lengths of time.

“Most people are using a definition of long COVID that reflects symptoms one to three months post-infection and with no limit on the length of time of those symptoms,” Duggal says. “The other part of the definition is on the type and variety of symptoms and if they are new or persistent. The WHO definition is consistent with clinical and research definitions that have not limited the type of symptom.”

Experts are hopeful a standardized definition will address the lack of clinical diagnosis for the condition. Meanwhile, scientists will continue to investigate if there’s anything that can be done in COVID-19's initial phase to prevent its progression to post-COVID-19.

“If we can predict who will have a worse long-term outcome versus those who may resolve symptoms, hopefully, we can provide better, targeted clinical care to those most in need,” Duggal says.

What This Means For You

Currently, the best available protection against COVID-19—and post-COVID-19—is to get vaccinated. If you haven’t booked an appointment yet, you can visit to find a vaccine provider near you.

What Comes Next?

“Defining long COVID is an important and necessary first step,” Duggal says. “Like anything, until we define the problem, it’s very hard to find solutions to address the problem. We expect the current definitions may change as we collectively learn more, and hopefully it will continue to be refined.”

A globally standardized definition is expected to help clinicians and health care workers diagnose patients and closely monitor their symptoms. As new evidence emerges, the definition may change.

“The official definition helps establish that post-COVID-19 is a condition, provides clinicians with guidelines that are well researched and gives us better tools and insight to counsel our patients,” Lambert says. “For my practice, there haven’t necessarily been any challenges, but the definition is helpful to improve the care we give and gives more specificity to make better diagnoses for our patients.”

Those who experience new or ongoing symptoms for weeks or months after first getting COVID-19 might find it helpful to visit their primary care providers. Aside from classifying patients’ health conditions, they can also offer guidance on how to navigate recovery along with the effects of the pandemic that are not related to the virus itself, such as insomnia, stress, or anxiety.

“It’s important for those who experience these symptoms after having COVID-19 to reach out to their family physician,” Lambert says. “When patients have an established relationship with their family physician, we can better identify conditions, like long COVID, because we already understand them and their medical history.”

Now guided by a clinical case definition, researchers will continue to investigate post-COVID-19 to understand what triggers the condition and develop appropriate treatments for patients. Everyone is advised to keep practicing well-established COVID-19 preventive measures to reduce the transmission of the virus.

“In the future, I see research focusing on creating clearer definitions of long-COVID, how to treat its symptoms and the overall condition, how long it takes for patients to get better, and what treatments help better reduce the symptoms,” Lambert says. “However, it’s important to note that prevention is always easier than treatment, so it’s important to get vaccinated against COVID-19 to prevent any concerns of post-COVID-19 conditions.”

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. World Health Organization. A clinical case definition of post COVID-19 condition by a Delphi consensus..

  2. Centers for Disease Control and Prevention. Post-COVID conditions.

  3. Alwan NA, Johnson L. Defining long COVID: going back to the start. Med (N Y). 2021;2(5):501-504. doi:10.1016/j.medj.2021.03.003

By Carla Delgado
Carla M. Delgado is a health and culture writer based in the Philippines.