'Vaccination, while first used in the 18th century, became mor | Bauhauswife

"Vaccination, while first used in the 18th century, became more widely implemented in the middle part of the century. Vaccines against diphtheria, tetanus, and pertussis became available during the late 1920s but only widely used in routine pediatric practice after World War II. Thus vaccination does not account for the impressive declines in mortality seen in the first half of the century."

PEDIATRICS| DECEMBER 01 2000
Annual Summary of Vital Statistics: Trends in the Health of Americans During the 20th Century 
Bernard Guyer, MD;
Mary Anne Freedman, MA;
Donna M. Strobino, PhD;
Edward J. Sondik, PhD
Johns Hopkins School of Public Health
https://doi.org/10.1542/peds.106.6.1307