As the COVID-19 pandemic approaches its fourth year, we can begin to gain some clarity on which countries, and which U.S. states, had the best outcomes over time. In a conversation with David Remnick, Dhruv Khullar, a contributing writer and a practicing physician in New York, explains some of the key factors. Robust testing was key for public-health authorities to make good decisions, unsurprisingly. What also seems clear from a distance, Khullar says, is that social cohesion was a decisive underlying condition. This helps explain why the United States did poorly in its pandemic response, despite a technologically advanced health-care system. Peer pressure, in other words, trumped mandates. Khullar also speaks to Dr. Rochelle Walensky, the head of the Centers for Disease Control and Prevention, about how misinformation and political polarization inhibit our country’s efforts on public health.