In such cases, it might be more ethical to monitor carefully the outcomes of different treatment centers now, before experimental treatments become available, and then compare these outcomes with those achieved by the same centers after experimental treatments are introduced. Unlike in a randomized trial, no one would receive a placebo, and it should still be possible to detect which treatments are effective.
但是，对于传染后致死率接近70%并且没有已被接受的现成治疗方法的埃博拉来说，患者可能理性地拒绝参与可能获得安慰剂的实验，还不如参与存在些许恢复希望的实验性治疗。在这种情形中，仔细监控眼下的不同治疗中心的结果，然后以相同治疗中心引入实验性治疗后所实现的结果作比较也许更符合道德。与随机实验不同，没人会得到安慰剂，并且仍有可能确定哪种治疗更加有效。