🦠 Pandemics & Disease

Background: why this matters

Pandemics are the natural catastrophe that has killed the most people in recorded history. The Black Death in the 14th century killed a large fraction of Europe's population. The 1918 influenza pandemic killed an estimated 50 million people worldwide, more than the First World War. COVID-19 showed how fast a new virus can reach every country: the WHO estimated about 14.9 million excess deaths in 2020 and 2021 alone.

The pathogens experts worry about most combine easy human-to-human spread with high lethality. Most new human diseases jump from animals, so surveillance focuses on spillover: bird flu viruses such as H5N1, which spread widely in US dairy cattle from 2024; coronaviruses such as MERS; and viruses such as Nipah, Ebola and Marburg, which are very lethal but usually spread less efficiently. Engineered pathogens are a growing concern because biotechnology is becoming cheaper and more widely available.

The main global early-warning system is the WHO's International Health Regulations, under which countries report unusual outbreaks. The WHO can declare a Public Health Emergency of International Concern (PHEIC), as it did for COVID-19 in January 2020 and for mpox in 2022 and again in 2024. In May 2025 the World Health Assembly adopted a Pandemic Agreement meant to improve prevention, preparedness and access to vaccines.

This factor uses the WHO's Disease Outbreak News: official notices the WHO publishes when an outbreak is serious or unusual enough to warrant international attention. We count how many notices appeared in the last 90 days and add a penalty for each distinct high-consequence pathogen among them. The notices are authoritative but lag reality by days to weeks, and WHO publishes updates on long-running outbreaks, so one serious outbreak can produce several notices.

What experts watch: signs of sustained human-to-human transmission of a new flu strain; outbreaks in dense cities or near airports; case-fatality and growth rates; antimicrobial resistance; laboratory biosafety; and funding for surveillance systems, which tends to shrink between emergencies.