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Signs You Already Had COVID, Says Mayo Clinic

Don't ignore some of the most common symptoms.
FACT CHECKED BY Emilia Paluszek

For decades, medical mysteries have been a fruitful source of material for TV shows and newspaper columns, but even those venues dedicated to baffling health conditions could have predicted the real-life medical mystery that is long COVID. Two years into the pandemic, experts still aren't sure why some people who contract COVID-19 are afflicted with long-lasting symptoms that endure well after the virus clears the body. According to a new study, about 30% of people who test positive for the coronavirus are affected. These are some of the most common signs of long COVID, according to the experts at the Mayo Clinic. Read on to find out more—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had COVID.



woman laying on bed with a phone in her hand.

"Because it's difficult to predict long-term outcomes from the new COVID-19 virus, scientists are looking at the long-term effects seen in related viruses, such as the virus that causes severe acute respiratory syndrome (SARS)," says the Mayo Clinic. "Many people who have recovered from SARS have gone on to develop chronic fatigue syndrome, a complex disorder characterized by extreme fatigue that worsens with physical or mental activity, but doesn't improve with rest."


Shortness of Breath or Difficulty Breathing

Sick woman feeling chest pain and wearing face mask in a lobby at medical clinic.

COVID-19 can cause shortness of breath during the acute infection. In some cases, the virus seems to cause damage to the lungs that can cause long-lasting breathing issues. You might develop a persistent cough or lingering cough, or become short of breath when exerting yourself or exercising.


Blood Clots


"COVID-19 can make blood cells more likely to clump up and form clots," says the Mayo Clinic. Large clots can cause heart attacks and strokes, much of the heart damage caused by COVID-19 is believed to stem from very small clots that block tiny blood vessels (capillaries) in the heart muscle. Other parts of the body affected by blood clots include the lungs, legs, liver and kidneys."


Organ Damage

pain. Chronic kidneys disease indicated with red spot on woman's body.

"Organ damage may lead to health complications that linger after COVID-19 illness," says the clinic. "In some people, lasting health effects may include long-term breathing problems, heart complications, chronic kidney impairment, stroke and Guillain-Barre syndrome — a condition that causes temporary paralysis."


Problems With Memory, Concentration or Sleep

Tired mature woman take off glasses suffering from headache

"Brain fog" has been a commonly reported long COVID symptom since the early days of the pandemic. The virus seems to cause neurological symptoms in some people, which can include problems with memory, difficulty concentrating, or insomnia. In some people, brain fog can be debilitating, even preventing them from resuming work once their acute infection is over. Mood issues, such as anxiety or depression, are also common.


How to Stay Safe Out There


Follow the fundamentals and help end this pandemic, no matter where you live—get vaccinated ASAP; if you live in an area with low vaccination rates, wear an N95 face mask, don't travel, social distance, avoid large crowds, don't go indoors with people you're not sheltering with (especially in bars), practice good hand hygiene, 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.

Michael Martin
Michael Martin is a New York City-based writer and editor. Read more about Michael