First state-level look at long COVID reveals the seven hardest-hit states

[moniss]

19. I wondered the same thing and

also if they were looking at only confirmed cases of Covid and if so how might the numbers change if we look at those who got Covid but didn't get diagnosed but now suffer from Long Covid symptoms. I know there are estimates I've seen for cases of initial infection not officially diagnosed. I think most of that was based on modeling. I don't know if their percentage of development of Long Covid can be inferred or not. One reason may be the variance in severity of Covid infection/medication intake etc. and development of Long Covid. We just may not know some of those things well enough to model or infer that kind of a case with any meaningful results.

My guess would be they used confirmed cases of initial infection and then subsequent Long Covid symptoms. That would be, at this juncture I think, the most reliable criteria for establishing the study groups etc.