5.5/ 10Borderline
Revised estimates of types and duration of long COVID symptoms based on claims records from 245 million US patients
Nilforoshan H, Reisler J, Jahanparast E, et al. · Proceedings of the National Academy of Sciences · 2026
Comparing people who tested positive with people who tested negative removes a real bias in earlier Long Covid studies, but the method averages over everyone infected, uses insurance codes that barely capture Long Covid, and its control group was increasingly infected over time, so it cannot show that Long Covid symptoms fade within a year.
Averages over all infected, hiding a sick minorityMany controls were infected later, mostly unrecordedHuge dataset, both designs run on the same data