 This study characterizes long COVID using data from the React2 community-based study in England. It estimates that 38% in autumn, winter 2021, and 22% in spring 2021 of people reported at least one symptom 12 weeks after symptom onset identifies risk factors for persistent symptoms and finds evidence of symptom clustering. This article was authored by Matthew Whittaker, Joshua Elliott, Mark Shadohaim, and others.