The Choice of Viral Load End Point in Early Phase Trials of COVID-19 Treatments Aiming to Reduce 28-Day Hospitalization and/or Death

Our study is the first to use IPD, allowing us to evaluate viral load collected on various study days as a surrogate to clinical outcomes. Change in log10(viral load) from baseline to day 3 or day 5 are moderate surrogates for 28-day hospitalization/death and suitable primary end points in phase 2 clinical trials and are preferred over change-from-baseline to day 7. Slope and AAUCMB require more calculation but did not improve prediction so are not recommended.