• Long Covid is a chronic illness resulting from a Covid-19 infection. It goes by many names, including long-haul Covid, post-Covid or post-acute Covid syndrome.
• Not much is yet known about the illness. Its symptoms number in the hundreds and can be debilitating. They can also be challenging to diagnose — for doctors even willing to do so.
• Long Covid has affected as many as 23 million Americans. It may cost the U.S. economy $3.7 trillion, roughly that of the Great Recession, according to one estimate.

Sam Norpel used to present regular financial updates to C-suite executives.

Now, unpredictable bouts of broken, staccato speech make that impossible for the former e-commerce executive.

Despite being up to date with vaccines and boosters, Norpel, 48, got Covid-19 in December 2021, when the highly transmissible omicron variant was fueling record U.S. caseloads.

She never got better — and in fact, feels worse, with a range of debilitating symptoms that make it impossible to work.

Her halting speech can be triggered by something as innocuous as cold water or cool air on the skin. Extreme noise sensitivity requires her to wear noise-canceling headphones all day. She's also endured a low-grade migraine for nearly a year, which can flare up after prolonged screen time.

When it comes to her body and mind, "the computer is just slow," said Norpel, who lives with her family outside Philadelphia. "Right now, for me, 48 [years old] feels like 78."

Norpel is one of millions of Americans with long Covid, also known as long-haul Covid, post-Covid or post-acute Covid syndrome. While definitions vary, long Covid is, at its core, a chronic illness with symptoms that persist for months or years after a Covid infection.

Up to 30% of Americans who get Covid-19 have developed long-haul symptoms, affecting as many as 23 million Americans, according to the U.S. Department of Health and Human Services.

Long Covid could be 'the next public health disaster'...

The country is about to enter its fourth calendar year of the coronavirus outbreak, and new variants are expected to make for a tough winter.

Researchers think most Americans have had Covid-19 at this point.

Studies suggest subsequent infections raise the chances of an "adverse" outcome, including hospitalization and death. The virus has killed more than 1 million Americans to date, and some 2,000 more die each week, according to the Centers for Disease Control and Prevention.

LISTEN: Long Covid is affecting millions of Americans. Here's what you need to know. https://t.co/jlJPGtz3i1

— CNBC (@CNBC) December 9, 2022

Long Covid demonstrates that the virus is taking a lingering, pervasive and perhaps even more insidious toll. Medical experts have called it "the next public health disaster in the making."

"There are just large numbers of people affected by this," said Dr. Peter Hotez, co-director of the Center for Vaccine Development at Texas Children's Hospital and a dean at Baylor College of Medicine.

That number will "only continue to grow" as Covid-19 continues to circulate, HHS said in a recent report.

"This could be game-changing in terms of how we do medical practice, in the same way HIV/AIDs was a game-changer," Hotez said.

... one with a significant financial toll

But the tentacles of long Covid reach far beyond its medical impact: from the labor gap to disability benefits, life insurance, household debt, forfeit retirement savings and financial ruin.

This article is the first of a CNBC special report examining long Covid's destructive impact on individuals, families and the U.S. economy at large.

All told, long Covid is a $3.7 trillion drag on the U.S. economy — about 17% of our nation's pre-pandemic economic output, said David Cutler, an economist at Harvard University. The aggregate cost rivals that of the Great Recession, Cutler wrote in a July report.

Cutler revised the $3.7 trillion total upward by $1.1 trillion from an initial report in October 2020, due to the "greater prevalence of long Covid than we had guessed at the time." Even that revised estimate is conservative: It is based on the 80.5 million confirmed U.S. Covid cases at the time of the analysis, and doesn't account for future caseloads.

Higher medical spending accounts for $528 billion of the total. But lost earnings and reduced quality of life are other sinister trickle-down effects, which respectively cost Americans $997 billion and $2.2 trillion.

"Long Covid will be around long after the pandemic subsides, impacting our communities, our health care system, our economy and the well-being of future generations," the HHS report said.

Norpel was the household breadwinner, which allowed her husband to care for their kids. The family has been living on income from a long-term disability policy, a vestige of her old job; the funds replace just a third of her prior pay. Norpel's husband must now juggle caretaking duties and the necessity of finding work, both for income and health insurance.

The money worries are multitude: the ability to continue funding her daughter's college education, the odds of raiding retirement accounts or selling their home to subsist. Norpel's 16-year old son recently wondered if he should get a job to support the family; but he doesn't even have a driver's license.

"All of it is just very heartbreaking," said Norpel, adding that "long Covid changed everything."

What is long Covid? It 'depends on who you ask'

While there are still many unknowns about long Covid — shorthand for its scientific name "post-acute sequelae of Covid," or PASC — what we do know so far is startling, experts say.

Anyone who's had Covid-19 can develop the condition. People can get it regardless of the severity of their initial infection or the virus variant, according to the World Health Organization. It affects all age groups, even those who were previously fit and healthy.

Studies suggest women are at higher risk than men; one study found adult females to be twice as likely to have long-haul symptoms. People of color are also more likely to get sick due to the increased likelihood of a Covid-19 infection and less access to high-quality health care; it's also more common in bisexual and trans people due to reduced care access and the stigma regarding their gender or sexuality, the HHS said in an October report.

However, the medical community hasn't arrived at an exact definition of long Covid, which complicates diagnosis and treatment.

The definition "depends on who you ask right now," said Dr. Greg Vanichkachorn, medical director of the Mayo Clinic's Covid Activity Rehabilitation Program.

Here are some of the points on which opinions diverge:

• Cause: Doctors don't yet know what causes long Covid. They have theories: Perhaps it's an autoimmune disorder, like lupus or rheumatoid arthritis, whereby the virus is gone but the immune system remains active, attacking healthy cells by mistake; or maybe small blood clots develop in the brain, too small to cause a stroke but big enough to trigger neurologic issues.

• Key symptoms: Long Covid has been linked to more than 200 symptoms, according to The Rockefeller Foundation. Shortness of breath, fatigue, and sleep disorders or insomnia are the most common symptoms, according to a recent global meta-analysis published in the Journal of the American Medical Association, a peer-reviewed journal. Others include anxiety, depression, body aches, headache, heart palpitations and "brain fog" — which describes challenges associated with cognition, like thinking, concentration, communication, comprehension, memory and motor function. Some sufferers have organ damage, to the heart, lungs, kidneys, skin and brain.

• Duration: There's no consistent definition of how long symptoms must persist for someone to be considered a long Covid patient. For example, the CDC says a person has long-haul symptoms if they persist beyond (or start after) one month from an initial Covid-19 infection. The WHO generally uses a three-month barometer. Different health clinics may use others still.

What experts do know is that for some, long Covid symptoms can last months or even years. About 15% of people whose ailments persist three months after infection continued to experience symptoms at least 12 months after infection, according to the meta-analysis.

Meredith Hurst, a paralegal, is one of those people. Hurst caught Covid in November 2020. She was diagnosed with long Covid in December 2021; now, two years after the initial infection, she still hasn't recovered.

The 42-year-old, who lives in Wilmington, Delaware, is unable to work and is in the process of filing for Social Security Disability Insurance — for which qualification is famously stringent. Brain fog, migraines and fatigue require her to complete the application in pieces; all of her progress, which had been saved in a draft, was recently deleted because too many days had elapsed.  

Meanwhile, Hurst is struggling to make ends meet. In addition to Medicaid health benefits, she receives public assistance via food stamps. Her credit cards are "getting maxed out."

"I don't know if it's for the rest of my life or not," Hurst said of feeling long Covid symptoms.

"It will probably continue this way for me until there is a test, a medication, more research, more education for the public, for doctors," she added. "This is going to be my experience for a while"

"It doesn't mean forever," Hurst said. "But for right now, this is my reality."

'All sorts of testing' to try for a diagnosis

The formal diagnosis code for long Covid used by researchers and physicians is only a year old.

The CDC authorized the code (U09.9) in October 2021. An official diagnosis allows patients to more easily access long Covid-related treatments, file for disability insurance and request accommodations at work, according to the HHS report.

Yet its nebulous nature means there isn't yet a definitive, yes-or-no lab test for it.

"There's no diagnostic test," said Dr. Jeff Parsonnet, an infectious disease physician who started the Post-Acute COVID Syndrome clinic at Dartmouth Hitchcock Medical Center. "It's really a clinical diagnosis."

Sometimes that process is straightforward: a confirmed, positive Covid-19 test result, with enough time passing after initial infection and persistent symptoms consistent with hundreds of other long Covid patients may be adequate, Vanichkachorn of the Mayo Clinic said.

But often, by the time Parsonnet sees patients at the Post-Acute COVID Syndrome clinic, they've had "all sorts of testing" from a primary care doctor or specialists. That might include pulmonary function tests or chest X-rays to look for heart or lung conditions, for example, magnetic resonance imaging (MRI) to identify brain inflammation or a "tilt table" test to evaluate a possible autonomic disorder.

Frustratingly for patients, such testing often comes back negative, according to medical experts, even as it adds to their financial burden.   

"In many cases, the diagnosis is [long Covid] because there's nothing else to explain the condition," said Alice Burns, associate director of the Program on Medicaid and the Uninsured at health care nonprofit The Henry J. Kaiser Family Foundation. "It's the diagnosis when all other diagnoses have been ruled out."

That can make some physicians unwilling to entertain long Covid as a reason for health complications.

"There are a lot of physicians or care providers who are reluctant to apply a label they see as defined as everything but the kitchen sink," said Diana Güthe, founder of Survivor Corps, referring to the litany of symptoms. Survivor Corps is a grassroots Covid advocacy group with about 250,000 members; Güthe herself had and recovered from long Covid.

Donna Pohl, 56, met with a neuromuscular specialist in mid-November to help treat nerve damage that resulted from long Covid. The visit didn't go well.

"[The specialist] said, 'Everyone wants to blame Covid,'" said Pohl, who lives in Bettendorf, Iowa, and was diagnosed with long Covid last December. "We are sick, not stupid or crazy."

People — including family and friends — often write off symptoms as "byproducts of anxiety and depression, or even worse, laziness and an excuse not to work," the HHS report said.

Neurologists would see Norpel twitch and instead focus just on her migraines, she recalled. One told her to stop reading literature on long Covid when she mentioned the disease during an appointment. "It was like Dr. 'Mansplaining,'" she said.

She eventually had a consultation in August at the Mayo Clinic, where she was told: "We believe you — you have long Covid."

"I started crying when the doctors spoke to me," Norpel said.