TL;DR:<p>- 3.5% of vaccinated people who get COVID and 7.7% of vaccinated get long COVID. (It was higher in the early strains.)<p>- 90% of people who get long COVID had mild COVID symptoms.<p>- symptoms last from months to a year or more.<p>- research shows immune responses to COVID infections are still evident two to three years after a mild infection.<p>- research hints it's an auto immune disease.<p>Not mentioned here, but I was always fascinated by a practising doctor saying to him long COVID looked very like the cases of chronic fatigue syndrome he had seen, and chronic fatigue seemed be triggered by a previous infection.