The largest epidemics take place in New Orleans. There are higher contagion and death rates among white Southerners than Black communities–particularly enslaved Black people. These disparate rates are used to "prove" race as a biological and essential difference, with little understanding of other factors contributing to immunity. Anthropologist Josiah Clark Nott of Alabama cites that "one-fourth Negro blood is more perfect protection against yellow fever than a vaccine is for smallpox."