Contagion and vaccines

The understanding of disease causation and spread is fundamental to the development of approaches to control. Although contagious diseases have been known through human history, it was not until the 19th Century that Robert Koch established the postulates that linked infectious agents with disease. John Snow’s intervention to stop cholera in London was a building block of infectious disease epidemiology, marking an evidence informed approach to disease control.  Although the first vaccine was developed without an understanding of disease causation, the control and subsequent eradication of small pox required an approach that built on the unique aspects of the disease and how best vaccination could be used. For the first 150 years since the small pox vaccine was developed, vaccine development relied on inactivation or the Jennerian approach. Over the past 70 years, starting with cell culture, the pace of change has accelerated. With the current pandemic, the explosion in technologies resulted in the many successful vaccines that are protecting people today. These technologies now hold the promise of better preparedness for the next contagion.