Methods
The “Home‐Based Intervention to Test and Start” (HITS) was a 2×2 factorial community‐randomized controlled trial in Umkhanyakude, KwaZulu‐Natal, South Africa, embedded in the Africa Health Research Institute's population‐based demographic and HIV surveillance platform (ClinicalTrials.gov # NCT03757104).The study investigated the impact of two interventions: a financial micro‐incentive and a male‐targeted HIV‐specific decision support programme. The surveillance area was divided into 45 community clusters. Individuals aged ≥15 years in 16 randomly selected communities were offered a micro‐incentive (R50 [$3] food voucher) for rapid HIV testing (intervention arm). Those living in the remaining 29 communities were offered testing only (control arm). Study data were collected between February and November 2018.Using routinely collected data on parents, conjugal partners, and co‐residents, a socio‐centric family network was constructed among HITS‐eligible individuals. Nodes in this network represent individuals and ties represent family relationships. We estimated the effect of offering the incentive to people with and without family members who also received the offer on the uptake of HIV testing. We fitted a linear probability model with robust standard errors, accounting for clustering at the community level.