https://www.tandfonline.com/doi/full/10.1080/21641846.2021.1922140 Leonard A. Jason, Mohammed F. Islam, Karl Conroy, Joseph Cotler, Chelsea Torres, Mady Johnson & Brianna Mabie Received 21 Apr 2021, Accepted 22 Apr 2021, Published online: 05 May 2021 Introduction Our objective was to determine which symptoms among long-hauler COVID-19 patients change over time, and how their symptoms compare to another chronic illness group. Methods 278 long-haulers completed two symptom questionnaires at one time point, with one recounting experiences during the first two weeks of their illness, an average of 21.7 weeks prior. We used a comparison group of 502 patients diagnosed with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Participants completed a standardized symptom questionnaire and a list of additional CDC COVID-19 symptoms. Results Over time, the long-haulers reported an overall reduction of most symptoms including unrefreshing sleep and post-exertional malaise, but an intensification of neurocognitive symptoms. When compared to ME/CFS, the COVID-19 sample was initially more symptomatic for the immune and orthostatic domains but over time, the long-haulers evidenced significantly less severe symptoms than those with ME/CFS, except in the orthostatic domain. Among the COVID-19 long haulers, several neurocognitive symptoms got worse over time, whereas improvements occurred in most other areas. Conclusions These types of differential patterns of symptoms over time might contribute to helping better understand the pathophysiology of those reporting prolonged illness following COVID-19.