Supply Resilience (SRS)
How well supply survives a shock. A fragile chain threatens the continuity of dose coverage itself.
Formula
Thresholds & Bands
| Band | Range | State |
|---|---|---|
| Robust | ≥ 75 | ok |
| Exposed | 50-75 | warn |
| Fragile | < 50 | crit |
Why This Metric Matters
Supply Resilience quantifies the Directorate's ability to maintain dose coverage and countermeasure availability through supply-chain disruptions. A fragile supply chain does not merely delay shipments — it creates gaps in population coverage that erode compliance, trigger narrative events, and expose the program to external scrutiny. PANACEA modeling indicates that a single-week interruption in priority-compound delivery to any managed region produces a measurable Compliance Index decline within 72 hours. SRS is therefore treated as a structural prerequisite for every downstream operational metric.
Threshold Justification
The index score of 75 as the robust floor was calibrated against historical disruption events, including the Q3 2024 precursor shortage and the Q1 2025 logistics-corridor closure. Below 75, the probability of a coverage gap exceeding 48 hours in at least one managed region rises above 15%. Below 50, PANACEA's Monte Carlo simulations project multi-region simultaneous failures with greater than 40% likelihood during any given disruption event.
Historical Context
SRS was formalized as a composite metric in Q2 2024 after post-incident review of the initial supply disruptions revealed that no single sub-indicator adequately captured systemic fragility. The index has ranged from 58 to 84 since inception, with the lowest readings corresponding to periods of single-source dependency for two critical API intermediates. Remediation efforts — including secondary-source qualification and strategic stockpile expansion — have lifted the baseline from 62 to approximately 78 over the past year.
Collection Method
SRS is computed weekly by the Supply Chain division as a weighted composite of three sub-indices: supplier redundancy (number of qualified sources per critical input), stockpile depth (weeks of reserve inventory), and single-source exposure (share of inputs with no qualified alternative). Data is aggregated through the Synaptic Data Fabric from manufacturing-site inventory systems, procurement databases, and Vector Fleet logistics telemetry. PANACEA applies scenario-weighted stress testing to adjust the raw composite for current threat conditions.
Known Failure Modes
The redundancy sub-index can produce misleadingly high scores when secondary sources are qualified on paper but have never been tested at production scale. Stockpile-depth figures may overstate usable reserves when inventory includes batches approaching expiration or lots held under quality investigation. Additionally, the weekly computation cadence means that rapid-onset disruptions — such as a facility incident or sudden export restriction — may not be reflected in the index for up to seven days after occurrence.