Most people who suffer from Covid-19 fully recover. Millions of other survivors find complete healing to be frustratingly elusive, in what’s often referred to as “long Covid.” Some experience extreme fatigue, shortness of breath and body aches, while others struggle with “brain fog” or haven’t regained their sense of smell or taste. More disturbingly, a subset become gravely ill much later, likely because of complications from their infection. The picture emerging from experience is that no single definition, explanation, diagnosis or treatment can be applied to the growing group, colloquially known as long-haulers, who reflect the pandemic’s lasting burden on societies and economies.
What is long Covid? There’s no universally accepted definition yet. According to the World Health Organization, people with what it calls “post Covid-19 condition” have symptoms usually three months after an initial bout of Covid that last for at least two months and can’t be explained by an alternative diagnosis. The prolonged symptoms -- sometimes entirely new to the patient -- include pulmonary, cardiovascular, gastrointestinal and nervous-system problems as well as neurological effects, such as cognitive impairment. Ailments may persist from the initial illness or appear after the acute phase of the disease -- even one with no noticeable symptoms. The symptoms may also fluctuate. Other groups have proposed alternative definitions. The U.K.’s National Health Service, for example, suggests referring to symptoms that last more than four weeks as “ongoing symptomatic Covid” and “post-Covid syndrome” if they persist for longer than 12 weeks and can’t be otherwise explained. Another definition may be needed for children.