Healthcare system disruption across WHO-declared PHEICs: a 4S comparative case analysis

Kim JM(#)(1), Lee JM(#)(1), Kim HO(2)(3), Kim YJ(4), Kim SS(5), Singh MK(5), Choi JW(6), Yeo SG(1)(2)(3). OBJECTIVES: To compare documented patterns of healthcare-system disruption and response across WHO-declared Public Health Emergencies of International Concern (PHEICs) using the established 4S surge-capacity framework (Staff, Stuff, Space, Systems) and an author-developed 12-indicator operationalization. METHODS: We conducted a structured comparative case analysis, not a systematic review of intervention effects, of all eight PHEIC events declared by WHO through 31 March 2026. The unit of analysis was the event, and the coded observations were operational occurrences documented in official sources. Twelve binary, unweighted author-developed indicators, three per 4S domain, were mapped to the four established domains. Activation required either one primary official source or two independent secondary sources meeting a prespecified threshold. Two reviewers independently assigned indicator-level codes, with disagreements resolved by consensus; indicators classified as Not Reported were combined with Not Activated. Activated indicators were summed within domains (range 0-3), and each observed configuration was assigned to one of four profiles using a fixed hierarchical rule sequence. RESULTS: All eight events activated at least one indicator, and external workforce mobilization (S1) and diagnostic bottleneck (T3) were documented in every event. COVID-19 was the only event activating all 12 indicators (systemic convergence). The two Ebola virus disease events shared an identical configuration of complete Staff, Stuff, and Systems activation with Space limited to temporary or repurposed facilities (workforce-cascade). H1N1 influenza, poliomyelitis, and mpox clade I formed the residual partial multi-domain category and did not share a common domain signature. Zika virus disease and mpox clade II met the limited-domain rule, with no Space-domain activation. CONCLUSION: …