An HDSS aims to systematically and continuously monitor the dynamics of a specified population in a geographically defined area, which lacks an effective system for registering demographic information and vital events.1–3 An initial census defines the target population and later, through periodic updating rounds, births, deaths and migrations are monitored. The first HDSS was implemented in 1940 in South Africa. There are now around 50 known HDSS worldwide, with surveyed population ranging between 13 350 and 260 000 individuals; 39 sites are spread in Africa, none of them in Central Africa or closest to Angola.