Under Tokyo's Coronavirus State of Emergency, the city's venues for the Olympics have no spectators. Recently, Tokyo has seen a surge in the number of cases of the highly contagious Delta variant, first detected in India and now spreading across the globe. This development raises new questions. How deadly is the variant? How effective are the vaccines? Can the Olympic and Paralympic games be safely conducted? And, will this pandemic ever end? We asked epidemiologist Dr. Caleb Alexander to share his insights.