Uncertainty is an inherent aspect of public health decisionmaking, especially in the context of high-impact, low-probability events such as pandemics. The catastrophic potential and number of disease scenarios that could manifest, the conflicting severe consequences of either overreacting or failing to act to mitigate a disease outbreak, and the challenge of detecting credible warning signals in a sea of noisy public health data create both demands for information to guide public health decisionmaking and wariness to act decisively in using it.