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Think You Have COVID? Here's How to Tell For Sure

Even vaccinated people may contract the virus.

With the return of mask guidelines, crowded ERs, and holiday warnings, the rise of the Delta and Omicron variants of COVID-19 might seem like deja vu from last winter. But that's not exactly true. First: Getting vaccinated has been proven to decrease your chances of severe disease. Second: The Delta variant is at least 60% more contagious than the earliest strain, and the typical symptoms of COVID infection may have subtly changed, one study has found. 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.


Sneezing or Runny Nose

woman cough sneeze in elbow

If you're not prone to seasonal allergies and find that you've been sneezing a lot, it could be due to COVID. The COVID Symptom Study has found that symptoms usually associated with a common cold or allergies, like a runny nose and sneezing, are increasingly common in COVID infections today. "If you've been vaccinated and start sneezing a lot without an explanation, you should get a COVID test, especially if you are living or working around people who are at greater risk from the disease," the researchers said.

"If you have any symptoms, no matter how mild, even if it is a sore throat, even if it is a runny nose, even if it is sinus congestion, go get yourself tested and limit your contact with other people until you do so," said Louisiana State Health Officer Joe Kanter about Delta earlier this month.

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young woman is ill stay in bed have a headache

An unusual or persistent headache is an increasingly common sign of COVID. Researchers with the COVID Symptom Study, who are tracking new COVID cases in people who are unvaccinated, fully vaccinated and partially vaccinated, found that headache was the #1 symptom reported among all three groups.  

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Chronic Fatigue

Woman lying on her bed with her eyes closed.

Fatigue is one of the most commonly reported symptoms of COVID infection. (In one survey of long-term COVID symptoms, fatigue was reported by 100% of respondents.) If you're experiencing fatigue that doesn't subside with rest, it's a good idea to consult your doctor.

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Loss of Taste or Smell

Last winter, a study at the University of Washington found that 30% of people who've had COVID experience persistent symptoms for as long as nine months after their initial illness. That study found that the second-most-common symptom was a loss of smell or taste. (No. 1 was fatigue.) But if you've been vaccinated, you might not experience that."Fever and loss of taste and smell are being reported to a lesser degree," said Dr. Andrew T. Chan, an epidemiologist and physician at Massachusetts General Hospital and one of the lead investigators of the Covid Symptom Study, in the New York Times.

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Brain Fog

Woman fainted

Many people who've had COVID report feeling unfocused or unable to concentrate, a.k.a. "brain fog," a symptom can last for weeks or months after their initial illness. Last August, a study published in the Lancet found than 55% of people diagnosed with coronavirus reported neurological symptoms three months after their diagnosis. 

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How to Stay Healthy

Nurse taking blood sample from young female patient in the background. Selective focus on sample tube.

Watch out for the more traditional symptoms of COVID-19 as well. "People with these symptoms may have COVID-19," says the CDC:

  • Fever or chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue
  • Muscle or body aches
  • Headache
  • New loss of taste or smell
  • Sore throat
  • Congestion or runny nose
  • Nausea or vomiting
  • Diarrhea

Get tested ASAP if you feel you might have COVID-19. And follow public health guidelines and help end this pandemic, no matter where you live. Get vaccinated ASAP. If you live in an area with low vaccination rates, wear a face mask that fits snugly and is double layered. Don't travel. Practice social distancing, avoid large crowds, 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 whose health and lifestyle content has also been published on Beachbody and Openfit. A contributing writer for Eat This, Not That!, he has also been published in New York, Architectural Digest, Interview, and many others. Read more about Michael