"The World Health Organization on Wednesday published a definition of long Covid for the first time, seeking to provide much-needed clarity on one of the most mysterious aspects of the coronavirus pandemic."

"The WHO estimated that 10% to 20% of Covid-19 patients experienced lingering symptoms for months following infection. These prolonged symptoms can include persistent fatigue, breathlessness, brain fog and depression. Health experts say the condition is clearly of public health concern, given the substantial impact it has on society, ranging from increased health care costs to economic and productivity losses."