In another study, the treatments with zinc or the placebo were begun before the volunteer subjects were purposely injected with a cold virus. The treatments were also continued afterwards. This is the only study to evaluate the effectiveness of zinc lozenges in preventing colds. The subjects in the zinc and placebo groups came down with about the same number of colds. The zinc lozenges therefore failed to prevent colds. However, and as experienced in the other trials, the severity of cold symptoms was significantly less in the group taking the zinc than in those taking the placebo.