Four substantive developments in the past year have elevated concerns about risks associated with the life sciences: the recognition of a potential existential threat to all life on Earth from the laboratory synthesis of self-replicating, so-called “mirror life”; accelerating evolution of artificial intelligence tools that can be used to design new biological threats and provide easier access to previously developed biological agents; continuing concerns about state-sponsored offensive biological weapons programs in a world of diminished norms and constraints on the exercise of power; and the rapid dismantling and degradation of US public health infrastructure, expertise, and capacity during the past year, coupled with the loss of trust in public health authorities and science—in the face of looming infectious disease threats such as avian influenza. The net effect of these developments is to leave Americans and others around the world at greater risk of harm from biological threats.

All life is composed of molecules that can exist in one of two different mirror-image configurations, just like left and right hands. This property of “handedness” is also called chirality. Most life on Earth uses biological molecules of the same chirality (e.g., sugars and nucleic acids are R-handed, amino acids are L-handed) and has evolved such that these molecules fit together and interact like a hand in a glove. Scientists beginning with Louis Pasteur have speculated about the possibility of mirror life, that is, cells and organisms composed entirely of biomolecules with the opposite chirality from that observed on Earth and have wondered why it apparently did not arise on this planet.

During the last decade, a handful of scientists have proposed synthesizing mirror life in the laboratory. They were motivated largely by curiosity and challenge and encouraged by technical advances in chemical synthesis of mirror-image versions of many key biomolecules that can be used to build and “boot up” mirror cells, as well as by progress towards the design and assembly of synthetic cells with natural chirality. In late 2024, 38 scientists from 9 countries published a detailed assessment of the risks of mirror life, arriving at a surprising set of conclusions: A mirror cell could find sufficient nutrients to grow in many habitats, including in humans, other animals, plants, and the environment; a mirror cell could plausibly evade normal controls on growth because of resistance to predation and immune control; and unchecked growth of a mirror cell could lead to widespread disruption and damage to most ecosystems, eventual widespread death of humans, other animals, and plants, and a potential existential risk to all life on Earth. These scientists urged that in the absence of compelling evidence that mirror life would not produce catastrophic results on Earth, the research community should not create mirror bacteria and other mirror cells.

Other scientists and policymakers in 2025 endorsed these findings and conclusions. Issues that remain unresolved include how to prevent the creation of mirror life without impeding other work in synthetic biology; which national and international governance mechanisms are best suited for managing the risks of mirror life; how to address questions about the possible need for detection, diagnostics, treatments, and preventive measures; and the most effective mechanisms for multilateral engagement.

Applications of large language models to biology and biological design tools grew exponentially in power and capability over the past year. Developments included more powerful AI tools that enable the design of new proteins—both beneficial and harmful—and genome language models that can design novel functional viruses. Because there are few safeguards against misuse of these tools and because the element of surprise strongly favors malicious actors, the risk of harm from misuse of AI tools has increased over the past year. Unfortunately, there are few if any incentives for the private sector to prioritize guardrails and AI safety measures, especially under current US political leadership.

During the past year—which marked the 50th anniversary of the Biological and Toxin Weapons Convention (BWC)—there were no meaningful measures to strengthen international control regimes against the development of biological weapons by states parties to the convention. On the contrary, the withdrawal of the United States from international engagement on this issue, the US failure to call out egregious violations of international law and norms by Russia, and China’s lack of transparency on biological research may have increased the likelihood that more resources will be devoted to the design, development, and possible deployment of biological weapons.

In the wake of the COVID-19 pandemic and political blow-back against governmental efforts to manage it, and with the dramatic change in US political leadership in January 2025, US pandemic preparedness and public health infrastructure have suffered major blows. Severe damage has arrived in multiple forms: severe cuts in funding for basic and applied public health research; reduced funding for non-commercially available biological countermeasure development and stockpiles; discontinuation of international, national, and local biosurveillance activities, leading to a loss of situational awareness; and reductions in US public health workforce and infrastructure support at the national and local levels. Damage has been amplified by an accelerating loss of trust in science, in public health interventions such as vaccines, and in public health authorities. The damage to US public health infrastructure has already caused strong, harmful secondary and tertiary effects around the world, none of which will be easily reversed.

All of this takes place against a backdrop of continued emergence and evolution of infectious disease threats such as avian influenza. Many public health and health security experts are convinced that the ability of the United States and others around the world to respond effectively to a new biological threat, regardless of origin, has been substantially degraded over the past year. This places millions more at increased risk of illness and death.

The heightened risks associated with these four developments could be mitigated by the adoption of multilateral agreements and national regulations to prevent the creation of mirror life; by cooperation between government and industry to impose meaningful measures for reducing the prospect that AI be used to create biological threats; by international engagement, especially by the United States, Russia, and China to re-affirm and strengthen the Biological Weapons Convention; and by restoring support for public health research, infrastructure, surveillance, prevention, and response capabilities to 2024 levels and by building upon this baseline to create a more anticipatory and resilient biodefense.

Read the 2026 Doomsday Clock statement »