Arnold Monto is a professor emeritus of epidemiology and of public health and codirector of the Center for Respiratory Virus Research and Response at the University of Michigan School of Public Health. Stephen Morrissey, the interviewer, is the Executive Managing Editor of the Journal. A.S. Monto and H.Y. Chu. The Best of Both Worlds — Using Clinical Trial and Observational Data to Evaluate Vaccine Protection. N Engl J Med 2026;395:313-316.