We’ve entered year three of the pandemic, and long Covid remains a mystery to experts, including how to cure its symptoms.⁠ ⁠ At this stage, even providing an estimate of how many people have long Covid is tough because symptoms vary, says Robert Gallo, director of the Institute of Human Virology.⁠ ⁠ “It’ll change tomorrow and next week, and it depends on whose criteria you’re using,” Gallo says. “We don’t even agree on how to define it yet, so it’s difficult.”⁠ ⁠ From common symptoms to the potential for clinical trials, check out everything we know about long COVID so far, in the link in bio.⁠