Figure 1.

Standardized script used in the Fourth Accelerating COVID-19 Therapeutic Interventions and Vaccines Host Tissue Platform to ascertain oxygen use after hospital discharge for the calculation of oxygen-free days for patients not receiving oxygen at baseline (before the acute illness). For patients who did use oxygen at baseline, similar questions are asked to ascertain oxygen use above baseline. These questions are asked by telephone, text message, or another telecommunication method during study visits after the patient has been discharged from the hospital. Answers to these questions are used to understand if the patient used oxygen after hospital discharge, and if so, when the final liberation from oxygen occurred.