Today, we have the technology to make vaccines against most infectious diseases and in theory we could free mankind from most of them. In spite of the great progress of science and technology, vaccines are an endangered species and there are increasing non-technological barriers to their development. Indeed, we have no mechanisms for developing vaccines needed only in developing countries, and in developed countries they are not a priority. Industry is walking away from vaccines and even the existing ones are in jeopardy. The reasons for the low interest in vaccines lie in the high risk and low profitability of the vaccine business. A story about the consequences that an infectious disease had on the economic development of the city of Siena in 1348 is used to show that our society is not calculating the intangible values deriving from vaccination. The failure of assigning the right value to vaccines and preventive medicine is a major risk of today's world that, having the opportunity of improving the proportion of healthy population, may have made the choice of increasing the number of chronically sick people.