Dylan Scott in Vox:
Three years since the beginning of the coronavirus pandemic in the US, the syndrome known as “long Covid” remains one of its chief mysteries.
Those mysteries include what the syndrome even is. The long-term fatigue and brain fog some people report after recovering from an acute infection are the symptoms most commonly associated with long Covid, but more than 200 distinct symptoms have been reported. The novel coronavirus may also change people’s cardiovascular systems permanently in ways that could lead to long-term health problems, even strokes and heart attacks. Is it all long Covid? There are other elusive questions: How frequently do people get long Covid? Who is at the highest risk of developing it? And what is causing these long-term symptoms in the first place? The remaining uncertainties can mask the scientific progress of the past few years. Scientists have a better idea of how long Covid works, and why it might cause a wide array of seemingly unconnected symptoms.
But — and this is more important than it might seem — we know what we don’t know. We have a stronger sense of what the most important unanswered questions are and where there is genuine debate among even the experts about this bedeviling condition.