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The One Sure Sign You've Already Had COVID

Long COVID has myriad symptoms, but this is the most common.
FACT CHECKED BY Emilia Paluszek

As pundits argue the validity of counting COVID-19 cases vs. deaths vs. hospitalizations, one number is left uncounted: the number of people who have a chronic illness due to COVID. All we know is, it's far, far too many to track. An estimated 10 to 30% of those who get the virus become "long haulers," with Long COVID, or PASC, symptoms that ruin their lives. And these aren't just old-timers who get severe COVID. These are also young, formerly vibrant people who got a mild case of coronavirus and were then cut down at the prime of their lives, suffering myriad symptoms that may never go away. What is the one telltale sign of Long COVID? Read on, keeping in mind that even if you've had COVID doesn't guarantee you're immune (get vaccinated!)—and to ensure your health and the health of others, don't miss these Sure Signs You Have "Long" COVID and May Not Even Know It.


Fatigue Exacerbated by Exertion is the Most Common Symptom of Long COVID

tired man
nimis69/ Getty Images

If you're feeling not just tired or sleepy, but abnormally fatigued by the slightest of chores, and this fatigue lasts for months, and you have unrefreshed sleep, you may have a post-viral infection due to COVID. Dr. Anthony Fauci, the chief medical advisor to the President and the director of the National Institute of Allergy and Infectious Diseases, has compared it to Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). The CDC calls that "a serious, long-term illness that affects many body systems. People with ME/CFS are often not able to do their usual activities. At times, ME/CFS may confine them to bed. People with ME/CFS have severe fatigue and sleep problems. Additionally, "Because COVID-19 can cause a decrease in oxygenated blood levels," says Sean Marchese, MS, RN. "People who overcame an infection may have experienced shortness of breath or dizziness with exertion." 

"There are a few sure signs, but the one key sign in everyone is fatigue. The stamina is just not the same. You're not able to perform at the same level you usually do," says Dr. Fahmi Farah. "You have a lack of stamina and overall fatigue." Read on for other key symptoms that might mean you had COVID.


You've Had Red and Runny Eyes

A businesswoman rubbing her eyes.

"Red and runny eyes is one of the most overlooked symptoms you've already had coronavirus. You may have been diagnosed with allergic rhinitis or conjunctivitis," Gail Trauco, R.N. "If you had red, irritated eyes accompanied by fever and body ache, chances are you have had coronavirus." Talk to your doctor about COVID.


Shortness of Breath and Cough

Blonde woman coughing.

"One of the first things that I tell my patients is to listen to your body for any subtle changes like tachycardia or shortness of breath or even a cough," says Dr. Michele C. Reed. "If you have been exposed to someone who had COVID-19 it increases the likelihood that you may come down with it within a 2 – 14 day period."


What Else is There to Know?

Young woman have headache migraine stress or tinnitus

PASC can result in nearly 200 symptoms, from fainting to tinnitus. "The hallmark is this vascular inflammation," says Dr. Bruce Patterson. "Now, why is that so important? Well, blood vessels are ubiquitous and this vascular inflammation is happening in the brain. It's happening in your organs, it's happening in the lungs, the chest, the heart. I mean, it is a unifying hypothesis that these blood vessels are doing, damage and causing inflammation in this widespread geography that we call the human body and can account for all the symptoms."

RELATED: 5 Ways to Prevent Dementia, Says Dr. Sanjay Gupta


What About the Delta Variant?

Doctor and senior woman wearing facemasks

"The Delta variant is not much different when it comes to symptoms. Despite being a novel and more transmissible strain, it can still resemble any other viral infection," says Dr. Liana Casusi. "A key difference is loss of taste and smell are not as common in these cases." "Unvaccinated persons who develop COVID-19 symptoms will likely experience much more severe symptoms that can cause long-lasting damage if not treated swiftly," says Marchese. To reduce your chances of getting COVID in the first place, get vaccinated ASAP and to protect your life and the lives of others, don't visit any of these 35 Places You're Most Likely to Catch COVID.

Alek Korab
Alek Korab is a Co-Founder and Managing Editor of the ETNT Health channel on Eat This, Not That! Read more about Alek