Public health as we know it arose in the nineteenth and early twentieth centuries, with improved nutrition, hygiene, sanitation and awareness of germs.

One innovation that stands out, though, is the invention of vaccines. The era of vaccines began just two centuries ago with Edward Jenner’s efforts to eradicate smallpox (a mission completed in recent decades under the leadership of Dr. Donald A. Henderson, a trustee of the group I work for, the American Council on Science and Health. The twentieth century saw the elimination or near-elimination of several deadly and debilitating childhood diseases and a significant curtailing of influenza.

Ironically, because people now take the healthier conditions created by vaccines for granted (rarely seeing the once-common sight of children crippled by polio, for instance), they sometimes dismiss vaccines’ benefits and exaggerate their (mostly imaginary) risks. With activists in the West falsely blaming autism on vaccines and Islamic conspiracy theorists blaming infertility on vaccines, we have seen lowered vaccination rates and resulting resurgences of diseases that should have been banished into the history books. Outbreaks of whooping cough in the US, mumps in the UK and polio in Nigeria remind us that science is still hampered by fatal superstition.

Todd Seavey is director of publications at the American Council on Science and Health, and editor of HealthFactsAndFears.com.