Doctors scramble to understand long Covid, but causes and prognosis are elusive

Reviewed by Emily Henderson, B.Sc.Apr 22 2021

One night in March 2020, Joy Wu felt like her heart was going to explode. She tried to get up and fell down. She didn't recognize friends' names in her list of phone contacts. Remembering how to dial 9-1-1 took "quite a bit of time," she recalled recently.

Wu, 38, didn't have a fever, cough or sore throat — the symptoms most associated with Covid-19 at the time — so doctors at the hospital told her she was having a panic attack. But later she developed those symptoms, along with difficulty breathing, fatigue and neurological issues.

Wu, of San Carlos, California, believes she had Covid — although, like many others who were unable to get tested early in the pandemic, she never got an official diagnosis. And, she said, its aftereffects continue to plague her.

Wu has struggled to get help from doctors, even those who take her symptoms seriously. “There’s no actual treatment,” she said, for people experiencing these lasting symptoms, often referred to as long Covid. When seeking help, “you’re basically a guinea pig at this point.”

For people suffering with lingering, debilitating symptoms months after a bout with Covid, pinning down a definition for long Covid may seem pointless. They just want relief.

"I don't care if it's Covid or some other illness," Wu said. "I want to get better."

But to public health experts, medical researchers and health care providers, understanding the causes, risk factors and spectrum of symptoms is vital.

"There's no single sign or lab test that can distinguish this syndrome from something else," said Dr. John Brooks, chief medical officer for the Centers for Disease Control and Prevention's Covid response. "Having something that we can use to define a [long-Covid] case is critical" for tracking how many people get it and how well they do, and to establish research criteria for clinical trials.

It's no easy task. There is no typical Covid "long hauler." After an infection, some people's initial symptoms don't abate, while other people develop entirely new symptoms that may affect multiple organs and systems. Studies have documented hundreds of lingering problems, but intense fatigue; chest pain; memory and concentration problems, often referred to as "brain fog"; shortness of breath; and a loss of taste and smell are common.

Having been hospitalized or placed on a ventilator isn't a reliable sign that someone will develop the condition. Many young, previously healthy people who had a mild initial infection are battling long Covid. Some people's symptoms drag on for months after their acute infection, while others' symptoms ebb and flow on a "corona coaster" of relapse and recovery.

In February, the National Institutes of Health announced a $1.15 billion, four-year initiative to study the causes and prevention of long Covid. The new research will bolster the growing number of studies that have already been published.

Younger and sicker

A year ago, when the novel coronavirus was surging through New York, Mount Sinai Health System created an app to monitor Covid patients at home, said David Putrino, the system's director of rehabilitation innovation. By early May it was apparent that roughly 10% of these non-hospitalized patients weren't getting better, he said. Many were younger and, until they got sick, healthier than the average Covid patient. And they were struggling with new symptoms they hadn't experienced in their original illness, such as heart palpitations and extreme fatigue.

An interdisciplinary team started to see these patients at what later became the Center for Post-Covid Care. Up to 30% of the patients have persistent symptoms that are a continuation of those they experienced when they were acutely ill, Putrino said. The other 70% tend to have novel symptoms that are specific to long Covid.

Mount Sinai's clinic, which manages the care of about 900 long Covid patients, is one of several dozen across the country devoted to Covid recovery, though the parameters for which patients they treat vary. Many involve multiple medical specialties, while others are dedicated to neurological or pulmonary symptoms or the aftereffects of ICU stays. Some require the patient to have a positive diagnostic or antibody test.

Putrino noted that some symptoms that Covid long haulers complain of are similar to those that affect people with "post-viral syndrome" who are recovering from serious infections like Ebola and Zika.

Such viral infections can cause severe inflammation and residual symptoms that last for months or years, said Dr. Steven Deeks, a professor of medicine at the University of California-San Francisco who is tracking people with long-Covid symptoms.

Other researchers have suggested that long Covid may actually encompass a number of separate syndromes, including post-intensive care syndrome, post-traumatic stress disorder or myalgic encephalomyelitis, sometimes called chronic fatigue syndrome. Still others note that some long Covid symptoms look like dysautonomia, a term for disorders of the autonomous nervous system, which regulates breathing and heart rate, among other things.

Whatever "long Covid" ultimately comes to mean, it continues to surprise medical experts. If someone has a serious bout of pneumonia, an infection that inflames the air sacs in the lungs, it's not surprising if they have a bad cough for a few months as their body slowly heals, said Brooks, of the CDC.

But with a Covid infection, sometimes that cough doesn't go away for many months, and along with it someone might have brain fog. Another might develop encephalitis, a swelling of the brain.

"This is not a cluster [of symptoms] that we see after a typical viral respiratory infection," Brooks said.

A push by patients

There are several working theories about what causes long Covid.

Some studies suggest that the virus or remnants of it may lurk in the body and continue to stimulate the immune system. Or the virus may have been cleared, but "the immune system keeps fighting against a perceived enemy, because it hasn't gotten the word that the war is over," said Dr. Michael Saag, a professor of medicine and infectious diseases at the University of Alabama-Birmingham who participated in a two-day workshop sponsored by NIH in December. Or tissues may have been damaged during the initial immune response, causing long-term symptoms.

Despite the imprimatur of respected researchers and public health experts, skeptics remain. Some doctors complain that the diagnosis is being propelled by interest groups rather than science. Others compare it to other chronic conditions, like fibromyalgia, for which there are no definitive diagnostic tests. Some suggest it is a psychosomatic illness.

Patients and their advocates played a crucial role in drawing attention to and gaining acceptance of long Covid.

After contracting Covid in March 2020, Diana Berrent started Survivor Corps as a Facebook support group; it has grown into a broader advocacy organization for Covid patients, with more than 150,000 members.

"Most of the people who we see suffering from long-term Covid were not the ones who were in the hospital and on ventilators," Berrent said. "These are people who mostly had what I had — what I call the 'Tylenol and Gatorade' variety of Covid," which they coped with at home.

Much like patients with myalgic encephalomyelitis/chronic fatigue syndrome, people with long Covid say finding supportive medical providers is a problem, said Emily Taylor, director of advocacy and community relations at the group Solve M.E. It recently co-founded the Long Covid Alliance with 21 other organizations to draw attention to post-viral illnesses.

Long Covid presents an opportunity to find answers not only for long Covid but also for a range of conditions that have struggled for research dollars and support.

"The post-viral research community is all coming together now to address Covid," Taylor said. "Frankly, there's no other option."

This story was produced by KHN, which publishes California Healthline, an editorially independent service of the California Health Care Foundation.