. 2022 Oct 1;16:100374. doi: 10.1016/j.lana.2022.100374

Table 1.

Definitions of public health ethics principles to guide the design of risk mitigation strategies.

Public Health Ethical Principle	Expanded Definition
Precautionary Principle (PP)	When significant risks to individuals and communities arise, but some uncertainty about the risk remains, prudent steps should be taken to mitigate the risk even as the evidence evolves. The PP places a penumbra of precaution over a number of sub-principles such as proportionality and reasonableness (risk/cost assessments, tradeoff considerations); responsibility (those creating risks should bear a greater burden of prevention); and reciprocity (shared benefit demand shared burdens).¹⁰ Intrinsic in the PP is the acknowledgement that there are ethical and practical risks of waiting for certainty before implementing safety measures, especially because certainty might never arrive. Science rarely achieves certainty and is permeated with language describing relative levels of uncertainty, exemplified by discussions of “statistical significance” and “confidence intervals” by “limitations” sections of research papers, and by frequent conclusions in science that “more research is needed.” In this light, the PP urges researchers, policymakers, and the public to make decisions based on the weight and credibility of evidence rather than awaiting elusive scientific certainty.¹¹
Harm Reduction (HR)	When a risky activity cannot reasonably be eliminated, whether because of social, political, legal, or cultural realities, steps should be taken to minimize the related harms of the risky activity, including minimizing its medical, social, and legal impacts. The HR principle is also described as a public health practice, philosophy, or social movement. The HR approach is predicated on recognizing that risky actions may be the result of forces beyond the control of an individual (such as resource shortages), and it is grounded in an approach of solidarity. Harm reduction “meets people where they are” and focuses on providing safer options when the safest option isn't realistic. While HR describes syringe and needle exchange programs and condom distributions programs, it also describes physical distancing, mask use, and privileging outdoor activities during the pandemic, all of which are HR strategies promoted in recognition that total social isolation for the duration of the pandemic is not feasible.¹²

Public Health Ethical Principle

Expanded Definition

Precautionary Principle (PP)

When significant risks to individuals and communities arise, but some uncertainty about the risk remains, prudent steps should be taken to mitigate the risk even as the evidence evolves. The PP places a penumbra of precaution over a number of sub-principles such as proportionality and reasonableness (risk/cost assessments, tradeoff considerations); responsibility (those creating risks should bear a greater burden of prevention); and reciprocity (shared benefit demand shared burdens).¹⁰
Intrinsic in the PP is the acknowledgement that there are ethical and practical risks of waiting for certainty before implementing safety measures, especially because certainty might never arrive. Science rarely achieves certainty and is permeated with language describing relative levels of uncertainty, exemplified by discussions of “statistical significance” and “confidence intervals” by “limitations” sections of research papers, and by frequent conclusions in science that “more research is needed.” In this light, the PP urges researchers, policymakers, and the public to make decisions based on the weight and credibility of evidence rather than awaiting elusive scientific certainty.¹¹

Harm Reduction (HR)

When a risky activity cannot reasonably be eliminated, whether because of social, political, legal, or cultural realities, steps should be taken to minimize the related harms of the risky activity, including minimizing its medical, social, and legal impacts. The HR principle is also described as a public health practice, philosophy, or social movement.
The HR approach is predicated on recognizing that risky actions may be the result of forces beyond the control of an individual (such as resource shortages), and it is grounded in an approach of solidarity. Harm reduction “meets people where they are” and focuses on providing safer options when the safest option isn't realistic. While HR describes syringe and needle exchange programs and condom distributions programs, it also describes physical distancing, mask use, and privileging outdoor activities during the pandemic, all of which are HR strategies promoted in recognition that total social isolation for the duration of the pandemic is not feasible.¹²