Fig. 1

Monthly trial activations over time. a Monthly trial activations for oncology, cardiovascular, and mental-health studies. The gray rectangular shaded area represents the initial pandemic period. The red squares and blue circles show observed non-US-based and US-based (respectively) monthly trial activation totals. The dark red line indicates the Poisson model-fitted (or predicted) non-US-based monthly activation totals; the lighter orange shows the model-based expected (or counterfactual) number of activations had the pandemic not occurred. Similarly, the dark blue line indicates the Poisson regression model-fitted US-based monthly activation totals, and the lighter blue line shows the model-based expected number of activations had the pandemic not occurred. Panel B) Observed monthly trial activations for COVID-19 studies. The red and blue lines show the observed number of trial activations for non-US-based and US-based studies, respectively