The World Health Organization (WHO) has published an official clinical definition of prolonged Covid, which is considered the "condition after Covid-19" and usually occurs three months after the onset of Covid with symptoms lasting at least two months.

"Common symptoms include fatigue, shortness of breath, cognitive dysfunction, but also others that generally affect daily functioning. Symptoms may be new, after the initial recovery from the acute episode, or continue from the initial illness. Symptoms may also fluctuate or recur over time, "explained Dr. Janet Diaz, Director of Clinical Management at WHO.

She added that the clinical definition is "an important step forward in standardizing the knowledge of patients living with the condition after Covid-19."

"We hope it will help health workers get to know patients. We hope health policy makers and systems create and implement integrated care models to care for these patients."

The WHO stressed that the definition may change as new evidence emerges "and our understanding of the consequences of Covid-19 continues to evolve."

One in three people infected with coronavirus will experience at least one symptom of prolonged Covid, a new study suggested . Recently, researchers at Oxford University, the Institute for Health Research (NIHR) and the Oxford Center for Biomedical Health Research (BRC) shed light on the problem after studying more than 270,000 people cured of coronavirus in the US.

"The results confirm that a significant proportion of people, of all ages, can be affected by a range of symptoms and difficulties in the six months after Covid-19 infection. Over a third of patients were diagnosed with at least one of the symptoms of Covidium lasted between three and six months after their illness, "said (via Guardian) Dr. Max Taquet.