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Signs You've Already Had COVID-19

Signs you had the virus without knowing it.
FACT CHECKED BY Emilia Paluszek

Although COVID-19 was officially declared a pandemic in March 2020, it's entirely possible you may have got the virus before that, and recovered without even realizing it. "Long-term COVID—or post-acute COVID—affects a multitude of organ systems," says Devang Sanghavi, MD. "Starting from head to toe, it leaves behind multiple symptoms in a large proportion of patients who have recovered from COVID-19." Here are five signs you've probably already been infected with COVID-19, according to experts. Read on—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had COVID.


That One Really Bad Cold

Young woman sitting alone on her sofa at home and coughing.

Did you have a cold that seemed worse than usual? The symptoms of COVID-19 are similar to those of cold or flu, so you may have had the virus without knowing it. "There is significant overlap between symptoms of influenza and COVID," says Laraine Washer, MD, medical director of infection prevention and epidemiology at Michigan Medicine. "Both can present with fevers, chills, cough, muscle/body aches, fatigue and headache." 


Lingering Brain Issues

Woman hands on his head felling headache dizzy sense of spinning dizziness with motion

Unexplained neurological issues could be a sign of COVID-19, doctors say. "At the population level, studies have found a higher incidence of neurologic and neuropsychiatric disorders among individuals infected with COVID-19 than among healthy control [individuals] or those with other respiratory tract infections," says Jonathan Rogers, Ph.D. "At an individual level, it can be quite difficult. With rare but serious manifestations such as stroke, there can be a clear temporal link to COVID-19, but other neurologic or neuropsychiatric syndromes such as headache or depression are very common in the population, so it is hard to know when to attribute them to COVID."


Ongoing Lung Issues

man using asthma machine at home.

"From a lung perspective, patients have persistence of shortness of breath, or dyspnea, and require ongoing oxygen treatment even after discharge and for weeks to months because of permanent damage to the lungs," says Dr. Sanghavi. "As far as the cardiac system is concerned, there's chest pain and shortness of breath."

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Sleep Problems

tired woman

There is evidence that COVID-19 can cause ongoing sleep issues for some, even months after they have recovered from the virus. "Once sleep is disrupted, it can impact mental and physical health, which may in turn cause further sleep disruption," says Athena Akrami, Ph.D, neuroscientist at University College London. "A vicious cycle may form that is very difficult to diagnose and treat properly."

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Nervous System Issues

Human brain on a dark blue background

If you're dealing with ongoing nervous system or autoimmune issues that are unusual, it could be a sign of COVID-19. "There are three main ways by which COVID-19 might affect the nervous system," says Dr Daniel Kondziella, clinical research associate professor in the Department of Neurology at Rigshospitalet, Copenhagen University Hospital. "First, the virus itself has some sort of neurotropism. That means the virus crosses the blood-brain barrier and enters the brain, where it damages the tissue directly. The other option is that there is an autoimmune response by which cross-reaction toward the virus particles induces a neuroinflammatory pathway in the brain. We did find that in our study to a relatively lesser extent, compared to the third category, which is peripheral nervous system damage not directly caused by the virus or by autoimmune responses, but more because of treatment-related disorders."

RELATED: Signs You Have Diabetes, Say Physicians


How to Stay Safe Out There


Follow the public health fundamentals and help end this pandemic, no matter where you live—get vaccinated or boosted 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.

Ferozan Mast
Ferozan Mast is a science, health and wellness writer with a passion for making science and research-backed information accessible to a general audience. Read more about Ferozan