So where did the economists get their data? From the epidemiologists would be my guess.
Based on that article, it appears they worked independently:
They looked at mortality rates but didn’t consider how lockdowns might have affected the number of infections or virus-related hospitalizations. They also didn’t use studies that forecast deaths.
The authors of the study are Jonas Herby, a special adviser at the Center for Political Studies in Copenhagen, Denmark; Lars Jonung, PhD, a professor of economics at Lund University in Sweden; and Steve H. Hanke, founder and co-director of the Johns Hopkins Institute for Applied Economics, Global Health, and the Study of Business Enterprise.
So no, I don't see any epidemiologists listed. As I said, you can find experts to prove any narrative. But who do you trust with your life?