medRxiv preprint;https://doi.org/10.64898/2026.02.18.26346597. This model application demonstrates that the sudden cessation of USAID and CDC commitments in the largest HIV epidemic in the world leads to increased incidence and mortality and threatens decades of progress in KZN, South Africa. Restoring funding within 12 months and increasing efficiency of HIV interventions can reestablish KwaZulu Natal province, South Africa’s trajectory toward EHE goals.