Science for Pandemic Preparedness: A Precautionary Framework.

In the early weeks of the pandemic year 2020, health agencies were slow to warn of the potential for a global health emergency while scientists waited for 'sufficient' evidence of human-to-human transmission of the new coronavirus. There were further delays and confusion in issuing guidance because of uncertainty about the most important routes of exposure. A 2021 international expert panel review of COVID-19 pandemic response concluded: 'The bias of the current system of pandemic alert is towards inaction-steps may only be taken if the weight of evidence requires them. This bias should be reversed-precautionary action should be taken on a presumptive basis, unless evidence shows it is not necessary'. To implement this recommendation, health agencies should incorporate the concept of precaution into their methods for rapidly and transparently reaching policy decisions. In this article, we summarise the historical development of precautionary policy frameworks, and present 4 key components. First, take action if potential risks are large, even when the science is uncertain. This corresponds to the common sense idea of 'better safe than sorry'. Second, consider the burden of proof required before choosing among alternative actions. Third, ensure that the full range of potential solutions is considered by broadly defining the problem and consulting all relevant scientific fields. Finally, increase public participation so that all relevant perspectives are included, and the chances of public buy-in are increased. Drawing lessons from past applications and missed opportunities, we propose steps that health agencies could take to incorporate precaution into a pragmatic approach to using science for pandemic preparedness and response. The risk of another pandemic from the highly pathogenic avian influenza A (H5N1) virus underscores the urgency of this new approach.