The Americas saw this rapid decline with arrival of Europeans. The diseases killed 90% of indigenous people ... Guns, Germs, and Steel, PBS adaptation ... "When the Europeans arrived, carrying germs which thrived in dense, semi-urban populations, the indigenous people of the Americas were effectively doomed. They had never experienced smallpox, measles or flu before, and the viruses tore through the continent, killing an estimated 90% of Native Americans." That far outstrips what we're likely to see in absolute numbers in this coming year worldwide from COVID-19.