The AHS Index is a new way to look at data that illuminates a snapshot of our world today. It is intended to highlight health inequities and spark conversation, debate, and wonder.
Percent of U.S. parents who kept their children up to date on the recommended childhood vaccinations in 2022: 90%
In 2025: 82%
Percent of parents who believe vaccinations cause autism: 26%
Number of children involved in a study that found no causal links between vaccinations and autism: 1,266,327
Number of children involved in the 1998 study by Dr. Richard Horton that turned tens of thousands of parents around the world against the measles, mumps and rubella vaccine because of an implied link between vaccinations and autism: 12
Year that study was retracted: 2010
Number of confirmed measles cases in the U.S. in 1997, a record low: 138
Number of confirmed measles cases in the U.S. in 2025, so far: 1,319
Number of children’s lives saved worldwide by vaccinations in the last 50 years, thanks to the World Health Organization’s Essential Programme on Immunization: 150 million
Percent of Americans who think the COVID-19 vaccine is the deadliest vaccine ever created: 25%
Number of lives estimated saved by the COVID-19 vaccine: 14.4 million