Herrett, Emily; Tomlin, Keith; Lin, Liang-Yu; Tomlinson, Laurie A; Jit, Mark; Briggs, Andrew; Marks, Michael; Sandmann, Frank; Parry, John; Bates, Christopher; +11 more... Morley, Jessica; Bacon, Seb; Butler-Cole, Benjamin; Mahalingasivam, Viyaasan; Dennison, Alan; Smith, Deb; Gabriel, Ethan; Mehrkar, Amir; Goldacre, Ben; Smeeth, Liam; Eggo, Rosalind MM; (2023) Protocol for an OpenSAFELY cohort study collecting patient-reported outcome measures using the TPP Airmid smartphone application and linked big data to quantify the health and economic costs of long COVID (OpenPROMPT). BMJ Open, 13 (2). e071261. ISSN 2044-6055 DOI: https://doi.org/10.1136/bmjopen-2022-071261