Temporal variations in the diagnostic performance of chest CT for Covid-19 depending on disease prevalence: Experience from North-Eastern France

•Chest CT accuracy was 85.4 % during ascending, peak and descending phases of the first Covid-19 wave.•It was not significantly different between chest (4 readers, accuracy 86.4 %) and general (6 readers, accuracy 85.1 %) radiologists, with a probability of equivalence ≥ 95 %.•There were important variations of CT predictive values whereas CT specificity remained stable over time.