6 Things You Need to Know About Long COVID

fstop123/Getty Images Facebook Twitter LinkedIn Common Long COVID Symptoms Tiredness or fatigue Difficulty thinking or concentrating (sometimes referred to as “brain fog") Headache Loss of

smell or taste Dizziness on standing Fast-beating or pounding heart Chest pain Difficulty breathing or shortness of breath Cough Joint or muscle pain Depression or anxiety Fever Symptoms

that get worse after physical or mental activities

Source: CDC

Millions of people who have been diagnosed with COVID-19 in the past year have reported new or lingering — and sometimes unusual — symptoms of illness, long after their initial infection. In

fact, it's become so common that clinics have popped up all over the country to study the phenomenon and help these so-called long-haulers get back to normal.

Here's what we know so far about what doctors are calling “long COVID” — and what we are still hoping to learn.

When the faculty at the George Washington (GW) University School of Medicine & Health Sciences launched its COVID-19 Recovery Clinic late last summer, they did so with hospitalized patients

in mind, knowing that those who were severely ill would likely have a longer road to recovery. What the clinic's founders didn't expect, however, was that post-COVID problems were “just as

profound” in people who had mild to moderate cases of the disease, says Monica Lypson, professor of medicine at GW and co-director of its COVID-19 Recovery Clinic.

"Right now, the majority of our patients have not been hospitalized,” she says.

This is not unique to GW's clinic. Jennifer Possick, medical director of Yale's Post-COVID Recovery Program, notes a similar trend — and so does Greg Vanichkachorn at the Mayo Clinic.

"We certainly do have some patients that had severe illness or were even in [intensive care], but that's not the majority of our population by any stretch of the imagination,” says

Vanichkachorn, an occupational medical specialist who leads the Mayo Clinic's COVID Activity Rehabilitation Program.

A handful of studies support what health care providers are seeing — that the virus can haunt people who were hardly affected by its initial infection. For example, a July 2020 report from

the Centers for Disease Control and Prevention (CDC) found that 20 percent of previously healthy 18- to 34-year-olds who had COVID-19 and were not hospitalized still weren't back to their

usual state of health two to three weeks after testing positive for a coronavirus infection.

Swedish researchers discovered that 26 percent of young and otherwise healthy health care workers who had mild COVID-19 had at least one moderate to severe symptom for at least two months

after their infection; 11 percent had at least one symptom that lasted eight months. Similarly, a pre-print study looking at health records in California found that 27 percent of people who

were never hospitalized for COVID-19 reported ongoing symptoms after 60 days.

It's hard to pinpoint exactly how many people experience new or persistent symptoms after a coronavirus infection, says Mark Avdalovic, a pulmonary and critical care specialist at University

of California Davis Health. But it's something researchers are hoping to better understand.

An early study published on long COVID found that more than 87 percent of 143 hospitalized patients with COVID-19 reported at least one persistent symptom following their initial diagnosis.

Other reports, however, show that the population affected is likely much smaller. A U.K.-based survey found that 13.7 percent of more than 20,000 participants who tested positive for

COVID-19 continued to experience symptoms for at least 12 weeks after the infection. Other experts estimate that about 10 percent of the population who had COVID-19 have lingering symptoms.

Possick says that since Yale's Post-COVID Recovery Program launched last summer, she and her colleagues have seen “a lot of traffic” — nearly 500 patients to date. But “that's still a very

small number,” considering more than 32 million Americans have tested positive for COVID-19 and many of them could be battling unrelenting symptoms.

"The majority of people with COVID are never hospitalized, and a lot of them are younger, they're working age. And so even if only a small fraction of those people has persistent post-COVID

conditions, mathematically it's still a lot of people,” Possick says.