In late April 2020 Dr. Freya Jephcott developed a persistently high fever. When she went to hospital three weeks later, she tested negative for COVID-19. A scan (an extra precaution, given her risky day-job) revealed inflammation in her body but couldn’t point to anything concrete. After two months of fevers she developed painfully swollen ribs and stabbing chest pains. Again, doctors couldn’t find a cause. Things settled but then months later she started experiencing a new range of symptoms: loss of balance, poor coordination, and constant tinnitus—alongside constant fatigue and breathlessness.