text: Characterizing long COVID in an international cohort 7 months of symptoms and their impact A significant number of patients with COVID 19 experience prolonged symptoms known as Long COVID Few systematic studies have investigated this population particularly in outpatient settings Hence relatively little is known about symptom makeup and severity expected clinical course impact on daily functioning and return to baseline health We conducted an online survey of people with suspected and confirmed COVID 19 distributed via COVID 19 support groups e g Body Politic Long COVID Support Group Long Haul COVID Fighters and social media e g Twitter Facebook Data were collected from September 6 2020 to November 25 2020 We analyzed responses from 3762 participants with confirmed diagnostic antibody positive 1020 or suspected diagnostic antibody negative or untested 2742 COVID 19 from 56 countries with illness lasting over 28 days and onset prior to June 2020 We estimated the prevalence of 203 symptoms in 10 organ systems and traced 66 symptoms over seven months We measured the impact on life work and return to baseline health For the majority of respondents 91 the time to recovery exceeded 35 weeks During their illness participants experienced an average of 55 9 25 5 mean STD symptoms across an average of 9 1 organ systems The most frequent symptoms after month 6 were fatigue post exertional malaise and cognitive dysfunction Symptoms varied in their prevalence over time and we identified three symptom clusters each with a characteristic temporal profile 85 9 of participants 95 CI 84 8 to 87 0 experienced relapses primarily triggered by exercise physical or mental activity and stress 86 7 85 6 to 92 5 of unrecovered respondents were experiencing fatigue at the time of survey compared to 44 7 38 5 to 50 5 of recovered respondents 1700 respondents 45 2 required a reduced work schedule compared to pre illness and an additional 839 22 3 were not working at the time of survey due to illness Cognitive dysfunction or memory issues were common across all age groups 88 Except for loss of smell and taste the prevalence and trajectory of all symptoms were similar between groups with confirmed and suspected COVID 19 Patients with Long COVID report prolonged multisystem involvement and significant disability By seven months many patients have not yet recovered mainly from systemic and neurological cognitive symptoms have not returned to previous levels of work and continue to experience significant symptom burden All authors contributed to this work in a voluntary capacity The cost of survey hosting on Qualtrics and publication fee was covered by AAs research grant Wellcome Trust Gatsby Charity via Sainsbury Wellcome center UCL 