Could You Have Long COVID and Not Even Know It?

Six years after the COVID pandemic transformed daily life, many people assume the worst is behind us. Yet new research suggests that millions may still have long COVID without realizing it. Fatigue, brain fog, sleep problems and digestive symptoms are often attributed to stress, overwork or simply getting older, but they may actually represent lingering consequences of a coronavirus infection that never fully resolved.

A major new study published in JAMA Network Open (May 27, 2026) analyzed the medical records of 457,950 people treated at 58 hospitals and affiliated clinics across the United States. The investigators found that approximately one in six people who contracted COVID-19 developed long COVID, also known as post-acute sequelae of SARS-CoV-2 infection (PASC). Even more concerning, nearly 90 percent of those identified with long COVID developed at least one chronic condition requiring ongoing medical management.

The researchers also discovered that traditional diagnostic codes captured fewer than half of the actual cases. That means millions of people may have long COVID without ever receiving a formal diagnosis.

The authors of the new study conclude:

“This multisite cohort investigation reveals systematic invisibility of a chronic disease epidemic following SARS-CoV-2 infection.

“Extrapolating our 14.54% chronic PASC prevalence to approximately 103 million documented US COVID-19 cases suggests that 15 million individuals are living with chronic post–COVID-19 conditions…”

“A natural question arising from these prevalence estimates is whether health systems should already be experiencing overwhelming demand from patients with PASC. We contend they are, but this burden manifests as unexplained increases in chronic disease management rather than as a discrete, labeled condition. Patients with chronic postviral conditions present to primary care with fatigue, to cardiology with dysautonomia [heart rate changes, blood pressure problems, fainting, etc], to endocrinology with new-onset diabetes, and to neurology with cognitive complaints, without the diagnostic code connecting these presentations to antecedent infection.”

In other words, millions of people are likely to have long COVID symptoms but not be diagnosed correctly. Our healthcare systems may be substantially underestimating the problem.

No one knows why some people suffer from long COVID and others seemingly get better. Could the coronavirus persist in hidden places within the body after initial recovery? Might it still be triggering long-lasting symptoms that go unrecognized?

Could Millions Have Long COVID Without Knowing It?

The experts estimate that more than 100 million Americans have had laboratory-confirmed COVID infections. The actual number is almost certainly much higher.

Many people never got tested. Others relied on home tests that were never reported. Some had such mild symptoms that they never suspected they had COVID at all.

As a result, millions of people may now have long COVID without connecting their symptoms to a coronavirus infection that occurred months or even years ago.

The new study found that 16.3 percent of patients developed PASC. If that percentage holds true nationally, the number of affected Americans could be staggering. The next time you are at a bank, supermarket or sporting event, look around. Whenever you see six people consider that one of them might have long COVID and not even know it. Sometimes the symptoms can be subtle.

What Symptoms Suggest You May Have Long COVID?

According to some very smart people who have studied this question in depth (Nature Reviews Microbiology, March, 2023):

“More than 200 symptoms have been identified with impacts on multiple organ systems.”

I will not list them all in this post. Here are just a few of the most common complaints according to the CDC (July 24, 2025):

• Tiredness or fatigue
• Symptoms that get worse after physical or mental effort
• Heart palpitations
• Difficulty concentrating (brain fog)
• Headaches
• Sleep problems
• Dizziness, especially upon standing
• Anxiety or depression
• Digestive disorders (diarrhea, stomach pain, constipation)
• Joint pain

Many of these symptoms are remarkably common. A lot of people complain of fatigue. Many struggle with poor sleep.

Brain fog is practically a household term these days.

As a result, people may assume these symptoms are simply part of modern life. But some individuals who have long COVID may actually be experiencing lingering consequences of a prior infection.

Why Some People Have Long COVID Remains a Mystery

One of the greatest frustrations for patients is that no one can predict who will develop long COVID. Some people become seriously ill with COVID and recover completely. Others have mild infections but continue struggling for months or years.

Researchers have identified risk factors, but there is still no clear explanation for why certain individuals have long COVID while others appear unaffected.

That uncertainty has left many patients feeling ignored, dismissed or misunderstood.

Modern Medicine Has Failed the Fatigued!

I recently reviewed the tragic history of chronic fatigue syndrome (CFS). That’s because we were among the first medical journalists to interview Paul Cheney, MD, PhD on our radio show in 1988. You can read all about Dr. Cheney and why “CFS was the Canary in the Coal Mine” at this link:

“How Medicine Keeps Failing the Fatigued: CFS, Long COVID and Long Vax”

Infectious disease experts downplayed the idea of ME/CFS (myalgic encephalomyelitis/chronic fatigue syndrome) for far too long. “Long Lyme” has also been discounted, though one of the country’s leading experts suggests that anywhere from 15% to 20% of people who catch Borrelia burgdorferi may not get over this infection even after a “standard” course of doxycycline. You can listen to our interview with Dr. John Aucott at this link.

Some Research Suggests the Coronavirus Might Persist in the Body:

Many healthcare professionals have been taught that we overcome infections in a relatively short period of time. If you catch a cold, the flu, Lyme disease or COVID, the theory goes that your body mounts a defense and eventually kills off the invading organism(s). That theory could be wrong!

A study published in PLoS Pathology, July 24, 2025 concludes that:

“…PASC may be more prevalent than estimated from self-reported symptoms in human studies.”

This research demonstrates that even mild infections can lead to symptoms many weeks or months later. Researchers at Oregon Health & Science University studied rhesus macaques. Even though they were unvaccinated, the animals did not become very sick when they were infected with COVID-19, and they recovered promptly. But six months later, many of them had signs of chronic illness.

The scientists studied these primates because they react much as humans do. They noted that there was evidence of persistent viral RNA in nose and mouth tissues as well as stool, indicating persistent infection of the digestive tract.

The monkeys had elevated markers of inflammation and hormones indicative of diabetes and heart disease. In addition, many were not sleeping well. All of the animals showed signs of changes following infection, but those that were obese fared worse. Specifically, they had persistent lung pathology even if they were not having trouble breathing.

The investigators conclude that their study:

“suggests that the true prevalence of PASC in the human population may be significantly underestimated.”

How Could the Coronavirus Hide in the Gut?

Harvard scientists announced that they found proteins from the SARS-CoV-2 virus in many patients’ blood as long as a year after the first diagnosis (medRxiv, June 16, 2022). The spike proteins they identified don’t usually last very long in blood, indicating that the body harbors active virus shedding bits and pieces. About 65% of those with long COVID had such proteins in their blood, while people with no persistent symptoms did not have evidence of viral proteins.

The authors of this study suggest that

“The presence of circulating spike supports the hypothesis that a reservoir of active virus persists in the body.”

What Does It Mean If the Microbes That Cause Coronavirus Persist?

Infectious disease experts like short-lived microbes. If a patient has pneumonia and a doctor prescribes penicillin, the infection should clear within a week or so. An ear or urinary tract infection usually gets better within three or four days after appropriate antibiotic treatment.

Some infections are harder to eradicate, though. Chronic Lyme disease is especially problematic. It can take months to overcome and some people have a much more challenging time of it. Tuberculosis can take six to nine months to wipe out. The virus that causes hepatitis C can take two to six months to cure with antiviral medication. And the virus that causes chicken pox (varicella-zoster) can linger in the body for many decades before it is reactivated and triggers a shingles attack.

If SARS-CoV-2 behaves similarly in some individuals, it could help explain why people who have long COVID continue to struggle with fatigue, brain fog, digestive disorders and other chronic symptoms.

If the Coronavirus Persists, Does That Lead to Long COVID?

Most infectious disease experts assume that once the immune system kicks in after a COVID infection, the virus is cleared from the body. The belief is that within a week or two, people are no longer infectious, and the virus has been wiped out.

But the Harvard researchers previously detected viral RNA from COVID-19 in stool samples of children with persistent symptoms. Other scientists have also found evidence that the SARS-CoV-2 virus may linger in the digestive tract for months or longer. This is especially true when these patients suffer long-lasting GI symptoms.

Are Doctors Missing Cases of Long COVID?

The new JAMA Network Open study suggests they may be. The researchers identified 74,560 cases of PASC among 457,950 COVID patients.

That represents 16.3 percent of the population studied. Yet traditional diagnostic coding systems captured fewer than half those cases. The investigators also found that 89.3 percent of long COVID patients developed at least one chronic condition requiring ongoing care.

The authors conclude that current surveillance systems are substantially underestimating the burden of disease. In short, many people may have long COVID without ever hearing those words from a healthcare professional.

What Should You Do If You Think You Have Long COVID?

If you have experienced persistent symptoms following COVID, it may be worth discussing the possibility of long COVID with your healthcare provider.

• Keep a symptom diary.
• Pay attention to patterns.
• Notice whether physical or mental exertion worsens symptoms.
• Document episodes of brain fog, fatigue, dizziness, digestive problems or sleep disturbances.

Although there is still no universally effective treatment, recognition is often the first step toward appropriate evaluation and management.

If any of this rings true, please take a few minutes to listen to our radio show:

Show 1466: Could Hidden Infections Be Driving Chronic Disease?

Just click on the arrow inside the green circle under the photograph. We think you will be impressed with Nikki Schultek’s story! You can even watch the video podcast to learn how she conquered her chronic symptoms.

What Does the Future Hold?

Researchers are exploring whether antiviral medications, immune-modulating therapies and other approaches might help patients recover from long COVID. The new JAMA Network Open study delivers a sobering message: long COVID is not disappearing.

The burden appears to be accumulating. That means we need better diagnostic tools, more coordinated care and much more research. Millions of people are still searching for answers.

We do not understand why our government is not spending an adequate amount on research to 1) better understand why so many people are still suffering from long COVID and 2) how to treat this condition effectively!

Final Words:

Have you had COVID? Did you completely recover? Are you sure?

Do you sometimes wonder whether fatigue, brain fog, poor sleep, digestive problems or unexplained aches might be connected to an infection you thought was behind you? The new research suggests that many people may have long COVID and not know it.

Please share your experience in the comment section below. Your story may help others recognize symptoms that have gone unexplained for far too long.

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