Based on the real life events, a Variola vera (smallpox) epidemic, which broke out in spring of 1972. Hospital scenes filmed at several Belgrade hospitals, including Gradska bolnica (aka City Hospital), the epicenter of the outbreak.
The identity of the UN epidemiologist (portrayed by Peter Carsten) is hidden under the all-body cover and face mask. The Carsten's voice, a native German speaker, was dubbed by another actor.
As of 2016 it was included in the #100 Serbian movies list (1911-1999) and protected as cultural heritage of great importance.