I think I have long COVID. What does that mean?

There is no universal definition of the condition, making it harder to track and treat

Feeling more fatigued or out of breath during and after exercise is a common symptom of long COVID.

Fabio Principe/EyeEm/Getty Images Plus

In the year before the omicron variant began to spread in the United States, an estimated one-third of 18- to 45-year-olds had gotten sick with COVID-19. Just three months later, that figure doubled, and I was among the people who caught the coronavirus for the first time.

I was in the first wave of people who got omicron in December 2021, as I was finishing my fall semester at Cornell University. On the day I received my positive test result, I knew it was coming. I had a sore throat, cough and my whole body ached. For the next several days, I was so tired that I had to sleep for more than half the day while trying to finish my final exams and help report on the outbreak for my college daily newspaper. Days later, after taking every vitamin, supplement and over-the-counter medicine I could get, I tried to get back to my normal routine, starting with a workout on Zoom. I found myself needing to stop every couple of minutes to catch my breath. 

Time passed. I began to exhaust the list of YouTube workouts, and I began to feel better, but I never really got to 100 percent. Six months later, my friends and family no longer asked: “Do you feel any better?” In some ways I do. But between feeling much more out of breath every time I go to exercise than I used to or often hitting a wall at 3 p.m., I’ve wondered: Am I among the estimated 1 in 5 people in the United States who have long COVID?

What initially seems like a simple question is actually much more complicated than yes or no. There is no biological test — no swab or blood test — to say that someone has long COVID. Doctors and public health organizations don’t have a universal definition of the condition.

Putting a name to it

While the disease caused by the novel coronavirus was given the name COVID-19 in February 2020, long COVID surfaced a few months later as a hashtag on Twitter when Elisa Perego began using the term in her tweets. The archaeology researcher who has become a long COVID advocate, first fell ill in late winter of 2020 in Lombardy, Italy. Three months later, she relapsed — her blood oxygen levels began to drop again, and she may have had a small blood clot in her lungs. This was not the same COVID-19 that Perego was seeing on the news.

“For me, the idea of long COVID was about reframing COVID,” she told me over e-mail because of ongoing symptoms that make it difficult to talk for long periods of time. The term not only gave her experiences a name but began to unite what was a growing group of those who had COVID-19 and couldn’t seem to shake the aftereffects.  

“Very prolonged positive tests were being talked about in Italy. A grassroots movement of people who weren’t recovering from COVID was burgeoning on Twitter and other media,” she says. “So I thought the hashtag and the name long COVID could be a way to link this growing community.” 

Since then, other terms have also been used: post-acute sequelae of SARS CoV-2 infection, or PASC, post-acute COVID-19 and post-COVID conditions. The U.S. Centers for Disease Control and Prevention uses that last one, writing broadly “post-COVID conditions are a wide range of new, returning or ongoing health problems that people experience after first being infected with the virus that causes COVID-19.”

The only clear distinction that health professionals seem to agree on when it comes to long COVID is that it is the emergence or change of symptoms some time after being infected with the coronavirus. But how long after and what those symptoms are aren’t universally agreed upon.

Right now, that may be for the best, experts say.

A broad definition helps people with long COVID recognize that they have it and receive the care they need, says neuroscientist David Putrino at the Icahn School of Medicine at Mount Sinai in New York City. It also helps people from historically excluded groups who have long COVID get a proper diagnosis, when they may have otherwise been written off and labeled as psychosomatic.

Yet, even with a broad definition, people might not know they have it. While recently recruiting for a long COVID clinical trial, Putrino found that about half of the people that reported they had “fully recovered” failed his screening for post-COVID conditions because they still had lingering symptoms.

Many of these people fall into a similar camp as I do: They are not debilitated but they are “slowed down.” And similar to me, Putrino says, many of them say that they have fully recovered but have one symptom that doesn’t seem to go away — like having trouble exercising or needing to go to sleep much earlier than they used to or noticing they need an extra cup of coffee in the afternoon. 

When COVID-19 becomes long COVID

A key question in knowing who has long COVID is defining when acute COVID ends and long COVID begins. And there is disagreement there, too. The CDC starts its clock for long COVID at four weeks post-infection, while the World Health Organization says it’s closer to 12 weeks. The National Institutes of Health, in recruiting for its initiative to study long COVID, defines “post-acute” as starting 30 days after infection for children but does not define the window for adults.

There’s risk in making the time too short or too long. Too short, and doctors may include people that are just having a particularly long bout of acute COVID. They are likely to recover regardless of treatment, so including them makes it difficult to determine if a long COVID treatment is effective. For his work, Putrino is firmly in “team WHO” because he says that there are people that are still dealing with the acute symptoms of being infected with SARS-CoV-2 four weeks in. 

“We do not want to propagate the narrative that a certain percentage of long COVID patients spontaneously recover,” he says. “That’s not the case. I think that the individuals who are sick at four weeks who then go on to recover without doing anything interventional were just individuals who were still sick with COVID and ultimately recovered.”

However, if the start point is too far off, it will delay people getting care.

This is why Perego leans toward the four-week timeframe so that people can seek care sooner. But she says that researchers may want to track changes in a person’s condition over longer periods of time. 

“Clinically, my hope would be to have support as early as possible. The timing of the disease development might change in different patients,” she says. “There might be changes into how the disease develops with vaccination and the new variants. But I don’t like the idea of letting people with no in-depth care to wait for the moment they match a specific clinical case definition, which might be an artificial construct and quite delayed.” 

In a lot of ways, defining long COVID is like trying to hit a moving target but better understanding how long COVID changes over time will help researchers “figure out exactly what it is and maybe what it isn’t,” says Josh Fessel, a senior clinical advisor at the National Center for Advancing Translational Sciences, a part of the National Institutes of Health. Aside from tracking timing, another way to do that is tracking symptoms. 

Symptoms of long COVID

I had what all of the experts I talked with see as the most common symptoms — fatigue and shortness of breath. But others have trouble thinking or concentrating, a pounding heart, joint or muscle aches to name a few (SN: 2/2/22). While this long list of potential symptoms casts as wide a net as possible, it also creates a “diagnosis of exclusion,” says Emily Pfaff, a clinical informaticist at the University of North Carolina at Chapel Hill. In order for patients to know they have long COVID, they must first prove that their symptoms don’t have other causes. 

“That is an effort to ensure that we’re not confusing long COVID with other stuff, but what that can do is sort of put patients on this kind of diagnostic odyssey where they’re trying to match up their symptoms and their physicians and providers are trying to match them up with various diseases only to rule those out in order to say ‘Yes, maybe this is long COVID,’” she says.  

What makes ruling conditions out and homing in on long COVID difficult is that long COVID has flavors; it doesn’t come with the same symptoms, and it may not be caused by the same thing in everyone who has it. “​​We envision that long COVID has at least seven different mechanisms,” says Joan Soriano, a medical epidemiologist who helped WHO write its definition of long COVID. “This is similar to chronic fatigue syndrome or post-intensive care unit syndrome. Accordingly, any definition of long COVID will not be simple.”

A definition of long COVID has to encompass people who may still have virus circulating in their bodies, those who may have had autoimmune issues following infection, still others who have microclots in their blood and maybe people like me with a nagging feeling of not being quite back to normal. As researchers try to understand long COVID, and how to treat it, they will need to differentiate between these different flavors, called endotypes, Putrino says. Different flavors will call for different treatments. Something like an antiviral will probably work only for those people whose long COVID symptoms are caused by viral persistence. A blood thinner wouldn’t work for them but could help those with microclots.

One thing that could help with grouping the flavors of long COVID and recognizing how symptoms persist in large groups of patients is artificial intelligence, Soriano says. This is the type of work Pfaff, at UNC, is currently doing. She is creating a machine learning algorithm that can look at a patient’s health records and predict if they will have long COVID. “It’s never going to be 100 percent,” she says. But her algorithm is beginning to be able to accurately predict who will have it, and she is beginning to use it to figure out what flavor they might have.

Data, however, can’t operate in a vacuum, she says. Researchers need information from people like me and many others to get a firm grasp on what long COVID is and how to treat it. Merging hospital data with survey data from patients is the only way forward on creating a definition, Pfaff says.

I’m still not sure where I stand with my own case. A couple of weeks ago, I felt sheepish even mentioning that having long COVID was something that was on my mind. Long COVID is not something that really comes up in my everyday conversations, especially as an active 22-year-old. That quickly changed when Putrino, unprompted, described a class of people who just can’t get back to working out, or need an extra cup of coffee to keep up with their pre-COVID pace. This described how I have felt for months to a tee. Putrino, Pfaff and Fessel agreed that I fall into what is generally a pretty large group of people with long COVID, and Fessel told me he wouldn’t bat an eye if I were to apply to enroll in the NIH’s clinical trial. 

Still, I struggled to use the term. I haven’t been put out of work as Perego and hundreds of thousands of others have. Despite my aversion to saying I have long COVID because it has disrupted the lives of so many more than it has my own, defining the broad spectrum of experiences it’s led to may be important. Until we have reliable tests for the condition, what matters is people sharing their individual experiences.

About Anil Oza

Anil Oza was the summer 2022 science writing intern at Science News. He graduated from Cornell University with a degree in neurobiology and science communication.

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