Treating countries is a tall order, requiring vastly different strategies than those used for healing sick people.
Two “medicines” are required to treat nations. One is to reduce the gap between the rich and the poor, thus reducing economic inequality. The other uses the gains from that redistribution to create healthy conditions in early life, when a large fraction of adult health is programmed.
This website presents a prescription to make the United States healthy again. It was one of the healthiest nations in the early 1950s, but now more than 50 countries achieve better health for their inhabitants.