SIR Epidemic on Contact Network — Ring Quarantine Tracing

β (transmit): 0.30 Trace prob p: 0.70 Trace delay: 2 New Outbreak Pause

Contact tracing: when a case is detected (I→R), exposed contacts are traced with probability p after a delay d. Quarantined contacts (Q) cannot transmit. Effective R_eff = β·k·(1-p·coverage)·(1/γ). High p and low delay can suppress outbreaks.