studied the effect of successive inoculations of weak doses of Vipera aspis venom on animals. Although proving that a greater resistance to low doses was possible, Kauffman was unable to achieve complete immunity against the venom at the lethal dose.

The breakthrough came with the use of serum from an immunized animal to counter the effects in an unexposed animal. This use a treatment for disease was pioneered in 1890 by Emil von Behring and Shibasaburo Kitasato,