Most people recover from COVID-19 within days or weeks, but some continue to experience symptoms for months or even years afterward. Known as Long COVID, this condition can affect anyone—including people who had mild infections—and may cause fatigue, brain fog, shortness of breath, rapid heart rate, sleep disturbances, and other symptoms that interfere with daily life. Researchers are still working to understand why some people develop Long COVID while others recover completely, but risk appears to be higher in people who had severe illness, underlying health conditions, or repeated infections. Although there is no single cure, treatments focused on symptom management, rehabilitation, and supportive care can help many people improve over time.  

For more information from the CDC:

https://www.cdc.gov/long-covid/resources/index.html

CDC Long COVID Information Center