De Kruif's boast: vaccine trials and the construction of a virus

This article describes the sustained effort by American researchers between the mid-1930s and the mid-1950s to develop an effective influenza vaccine. From almost the beginning of this project, researchers succeeded in protecting laboratory animals from lethal influenza infection, and they believed that success with humans would follow quickly. Yet although they succeeded in producing a vaccine that proved effective in field trials in 1943 and 1945, that same vaccine failed to offer any protection in 1947. This vaccine failure forced researchers to reconsider the growing evidence of antigenic variation and challenged the model of the virus that had been taken for granted.