It's quite simple. They needed a typhus vaccine so they wouldn't need to use all of the zyklon-b for delousing. That way even more jews could be gassed behind wooden doors when they weren't being fooled by fake doctors to stand against walls that had narrow openings that the guards could sneak up behind and shoot them in the back. Not all the camps could afford the time and money of extermination by rollercoaster or masturbation machinery. This clever doctor, or more specifically, his descendants and loosely affiliated acquantainces, should be rewarded with shekels, many shekels, from this day forward.