Hulme W, Williamson E, Horne E, Green A, McDonald H, Walker A, Curtis H, Morton C, MacKenna B, Croker R, Mehrkar A, Bacon S, Evans D, Inglesby P, Davy S, Bhaskaran K, Schultze A, Rentsch C, Tomlinson L, Douglas I, Evans S, Smeeth L, Palmer T, Goldacre B, Hernán M, Sterne J. Challenges in Estimating the Effectiveness of COVID-19 Vaccination Using Observational Data. Annals Of Internal Medicine 2023, 176: m21-4269. PMID: 37126810, PMCID: PMC10152408, DOI: 10.7326/m21-4269.Peer-Reviewed Original Research