NIH-funded research effort identifies most common symptoms, potential subgroups, and initial symptom-based scoring system – with aim of improving future diagnostics and treatment. Initial findings from a study of nearly 10,000 Americans, many of whom had COVID-19, have uncovered new details about long COVID, the post-infection set of conditions that can affect nearly every tissue and organ in the body. Clinical symptoms can vary and include fatigue, brain fog, and dizziness, and last for months or years after a person has COVID-19. The research team, funded by the National Institutes of Health, also found that long COVID was more common and severe in study participants infected before the 2021 Omicron variant. ....