In three months of persistent work (one of his assistants experienced a nervous breakdown; two others quit), a form for human trials was ready and on 10 January 1897[12] Haffkine tested it on himself. "Haffkine's vaccine used a small amount of the bacteria to produce an immune reaction."[13] After these results were announced to the authorities, volunteers at the Byculla jail were inoculated and survived the epidemics, while seven inmates of the control group died. "Like others of these early vaccines, the Haffkine formulation had nasty side effects, and did not provide complete protection, though it was said to have reduced risk by up to 50 percent."[11][13]