Suppression, delayed containment, or no intervention: optimal strategies for pandemic control

Future pandemics will require policymakers to balance reductions in infections and mortality against the societal costs of interventions. Using an integrated epidemiological-economic framework combining an age-structured SEIR model with endogenous behavioral responses, healthcare capacity constraints, Test-Trace-Isolate-Quarantine (TTIQ), and a unified measure of societal costs, we find that optimal intervention strategies cluster into three distinct regimes: Suppression, No/negligible intervention, or Delayed containment, where initial spread is followed by a short period of stringent interventions and subsequent control through TTIQ. By contrast, prolonged mitigation (Flatten-the-curve) strategies are optimal only in a narrow set of scenarios. The three-regime structure is robust across a broad parameter space of 4 320 scenarios, spanning transmissibility, disease severity, valuation of health losses, healthcare overcapacity costs, and vaccine timing. This pattern reflects non-convex trade-offs governing pandemic control: intermediate interventions often incur both substantial infection-related costs and substantial intervention costs. The framework provides a general approach for evaluating pandemic preparedness and intervention strategies.