The World Health Organization released a clinical definition of post COVID-19 illness Oct. 6 that was developed by patients and researchers.
"Post COVID-19 condition occurs in individuals with a history of probable or confirmed SARS-CoV-2 infection, usually three months from the onset of COVID-19, with symptoms that last for at least two months and cannot be explained by an alternative diagnosis," the definition says.
"Common symptoms include fatigue, shortness of breath, cognitive dysfunction but also others and generally have an impact on everyday functioning. Symptoms may be new onset following initial recovery from an acute COVID-19 episode or persist from the initial illness. Symptoms may also fluctuate or relapse over time."
This is the first version of the definition and it may change over time as new evidence emerges, the WHO said.
Estimates on the number of COVID-19 patients who experience symptoms after their initial infection has cleared range from 10 t to 30 percent.