Chase was "SNL"'s first breakout star, and was also the first cast member to leave the show, after the second season had wrapped. New variant CJD, which has claimed more than 50 lives in Britain, tends to affect younger people. The vaccines, using UK-sourced cattle material, were made by two companies, Wellcome and Smithkline, despite warnings that they could pose a risk. If anything positive had come through, it would have been bad news. Both are forms of spongiform encephalopathy that produce vacuoles, or holes, in the brain.