Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “The study statistician (JL) based in Pretoria, who had no knowledge of the study area, randomly generated the allocation sequence for each stratum. Then enrolled participants.” Comment: random sequence generation was adequately done
Allocation concealment (selection bias)	Low risk	Quote: “The study statistician (JL) based in Pretoria, who had no knowledge of the study area, randomly generated the allocation sequence” Comment: allocation was adequately concealed
Similar baseline characteristics	Unclear risk
Similar baseline outcome measurement	Unclear risk
Blinding of participants and personnel (performance bias)	Low risk	Comment: personnel (field workers and interviewers) could not be blinded and were used for quality control of the measures. There was active recruiting the villages for participants in the study, again given the nature of the intervention blinding was not possible.
Blinding of outcome assessment (detection bias)	Low risk	Quote: “All blood tests were conducted blind to the treatment arm” Comment: outcome assessment was blind
Incomplete outcome data (attrition bias)	Low risk	Quote: “No clusters were lost to follow‐up.” “Loss to follow‐up was mainly because participants had moved and could not be located.” Comment: missing outcome data is balanced across groups
Prevention of knowledge of allocated intervention	Unclear risk
Protection against contamination	Unclear risk
Selective reporting (reporting bias)	Unclear risk	Comment: insufficient information to permit judgement and no protocol was found.
Other bias	Low risk	Comment: no evidence to suggest this