Will a global pandemic causing at least 10 million deaths occur between September 21, 2026 and December 31, 2100?

probability: 90%

rationale:

The threshold for a qualifying event is remarkably low relative to historical pandemics and projected population growth. A toll of 10 million deaths represents roughly 0.1% of the expected late-century global population un.org. Historically, multiple pandemics have vastly exceeded this scale: the 1918 influenza caused an estimated 50 million or more deaths, HIV/AIDS has claimed roughly 40 million who.int, and COVID-19 resulted in 18.5 to 35.2 million excess deaths as of late 2026 en.wikipedia.org. Crucially, because the resolution criteria explicitly permit excess-mortality accounting and accumulation across recurring waves of a single pathogen, the effective bar is only about one-third of COVID-19's lower-bound excess estimate who.int. Even a pandemic considerably milder than COVID-19 per capita, such as a modern equivalent of the 1957 or 1968 influenza pandemics, would plausibly clear the 10-million mark once excess mortality is counted.

Quantitative risk models imply a high cumulative probability over the 74-year window. Analysis of 400 years of epidemic data estimates a recurrence time of roughly 129 years for a COVID-19-intensity event pnas.org. Other estimates, such as those from the Center for Global Development, place the annual probability of a respiratory pandemic causing at least 10 million deaths at approximately 4.2% cgdev.org. Even adopting a highly conservative annual hazard rate of 1.5% to 2% for a sub-COVID-scale event, the cumulative probability over a 74-year period reaches 68% to 77%. When factoring in the lower 10-million-death threshold and the allowance for excess mortality, the baseline statistical likelihood of avoiding a qualifying event through 2100 becomes extremely small.

Current conditions and long-term trends point to elevated, rather than reduced, biological risk. Global health assessments consistently conclude that pandemic risk is outpacing preparedness investments, with infectious disease outbreaks becoming more frequent and damaging 2 sources. Drivers such as climate change, ecological encroachment, and dense global mobility are accelerating zoonotic emergence rates, which evidence suggests could triple in the coming decades pnas.org. Furthermore, the threat of engineered pathogens is widely judged to be growing. Advances in synthetic biology and AI are lowering the barriers to creating dangerous pathogens, introducing a severe, non-natural tail risk that historical base rates do not fully capture 3 sources.

The primary pathway to avoiding a 10-million-death pandemic hinges on a mid-century technological transformation in biodefense. Universal vaccines, broad-spectrum antivirals, ubiquitous metagenomic surveillance, far-UVC deployment, and AI-designed countermeasures could theoretically cap future pandemic mortality well below the threshold. Initiatives like the 100 Days Mission aim to drastically reduce response times, though current R&D investments have seen declines and the 100-day target remains unachievable in many areas ippsecretariat.org. While these biomedical and surveillance advances have the potential to genuinely suppress pandemic mortality in the latter half of the century, this optimistic scenario must contend with an extended period of vulnerability over the next few decades, where biological capabilities are advancing faster than defensive governance and technology.

Ultimately, for this event not to occur, the world must navigate the next 74 years without a single natural or engineered pathogen reaching roughly one-third of COVID-19's lower-bound excess death toll. This would require an unprecedented streak of luck across a period of growing population, rising zoonotic emergence, and accelerating deliberate or accidental engineering risks. Weighing the highly favorable mathematical compounding of annual hazards against the genuine possibility that future biodefense technologies successfully eradicate pandemic risk earlier than expected, a 90% probability accurately reflects the overwhelming historical base rates and systemic vulnerabilities while leaving a small margin for transformative mitigation.