The sequel to Exercise Mataika — a tabletop exercise expanding the Fiji smallpox bioterrorism scenario to test global pandemic response, with mathematical modelling showing that every day of vaccination delay dramatically increases epidemic size. Conducted just weeks before COVID-19 emerged.
View Evidence Cards Back to HubPacific Eclipse expanded Mataika’s Fiji scenario to model global pandemic dynamics and test vaccination response timing.
Pacific Eclipse was conducted in December 2019 — the same month that the first cases of SARS-CoV-2 appeared in Wuhan, China. While the exercise focused on smallpox, its findings about speed of response, global coordination failure, and resource competition proved immediately relevant to the emerging COVID-19 pandemic.
The exercise’s core mathematical modelling showed that delays in commencing vaccination result in “substantial epidemic growth.” A 7-day delay in beginning ring vaccination approximately doubled the total epidemic size. This finding directly applies to any pandemic — speed of initial response is the single most important variable.
The scenario continued from Exercise Mataika (2018): the smallpox bioterrorism attack originates in Fiji and spreads globally. Pacific Eclipse expanded the simulation to test global vaccination logistics, WHO stockpile deployment, international coordination, and the impact of varying response speeds on epidemic trajectory.
The WHO vaccine stockpile comprised 2.7 million doses held in Geneva and 31 million doses pledged by member states. But “pledged” does not mean “available.” In the scenario, countries facing domestic epidemics refused to honor pledges. Only 10% of total doses were actually held by WHO, with the rest being promises from nations that broke them under pressure.
Ring vaccination (tracing and vaccinating contacts) was the strategy that eradicated smallpox. Pacific Eclipse tested whether this approach could work in a modern bioterrorism context with simultaneous international spread. The conclusion: ring vaccination is optimal for limited supplies, but requires human resources and infrastructure that most countries lack.
Pacific Eclipse included significant military participation through US INDOPACOM. The exercise demonstrated the military’s critical role in logistics, surge capacity (temporary facilities, tentage, catering), and border security during biological crises. Military medical personnel were identified as essential first responders who should be pre-vaccinated.
The exercise used mathematical models to show how response speed determines epidemic outcome.
Cross-sectoral stakeholders from defense, public health, academia, and international organizations.
Building on Mataika’s framework, Pacific Eclipse quantified the impact of response variables.
Every day of delay in beginning vaccination dramatically worsens outcomes. The modelling showed that response speed is the single most influential variable — more important than the total number of vaccine doses available. This finding has universal applicability beyond smallpox.
The WHO stockpile’s “pledged doses” model failed under pressure. Countries broke pledges when facing domestic crises — precisely the vaccine nationalism dynamic observed during COVID-19 with COVAX. Physical stockpiles matter more than political promises.
The diagnostic delay in the Fiji scenario (13 days to confirm smallpox) allowed thousands of secondary infections. Investment in rapid point-of-care diagnostics and syndromic surveillance could dramatically reduce this window. Every day of diagnostic delay amplifies exponential spread.
The Pacific region’s unique geography (dispersed islands, informal maritime travel) makes containment extraordinarily difficult. Building regional diagnostic and response capacity in peacetime is essential. The exercise demonstrated that external aid arrives too slowly to prevent catastrophic spread in vulnerable regions.
Pacific Eclipse’s findings were validated within weeks as COVID-19 demonstrated every predicted pattern.
Pacific Eclipse was conducted in December 2019, the exact month SARS-CoV-2 emerged. While the exercise focused on deliberate smallpox release, its conclusions about:
All of these patterns played out in the real pandemic that began as the exercise concluded.
1. MacIntyre CR, Heslop DJ, Nguyen P, Adam D, Trent M, Gerber BJ, “Pacific Eclipse — A tabletop exercise on smallpox pandemic response,” Vaccine, 2022; 40(17). DOI: 10.1016/j.vaccine.2021.11.004
2. Tripoli (2021), “Pacific Eclipse exercise: value to US Indo-Pacific Command Surgeon’s Office,” Vaccine, 40(17).
3. MacIntyre CR et al., “Exercise Mataika: White Paper on response to a smallpox bioterrorism release in the Pacific,” Global Biosecurity, 2019.
4. Lee R, et al., “Use of a pathogen X tabletop exercise to assess the preparedness,” Vaccine, 2025.
5. MacIntyre CR, “Early detection of emerging infectious diseases,” Vaccine, 2024.
6. WHO, “Advisory Committee on Variola Virus Research,” Annual Reports, 2018–2020.