Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "We randomly assigned infants to receive either vitamin A or a placebo. The unit of randomisation was the individual infant. Block randomisation was done at WHO (Geneva, Switzerland) in block sizes of 20 (ten infants received vitamin A and ten received placebo)"
		Comment: Most likely done
Allocation concealment (selection bias)	Low risk	Quote: "The vitamin A and placebo capsules were identical in taste and appearance. Capsules were individually packed in blister packs of two capsules each; one for the dose and the second for the backup dose. Labels for the capsules were printed at WHO with country and infant study number in sequential order"
		Comment: Most likely done
Blinding of participants and personnel (performance bias)	Low risk	Quote: "Codes for the experimental regimens were kept with the data and safety monitoring board and broken during the analysis after a cleaned and locked database for the study was submitted to WHO"
		Comment: Most likely done
Blinding of outcome assessment (detection bias)	Low risk	Quote: "All reported deaths of children were investigated and trained field staff visited the family at least 6 weeks after the date of death to do a verbal autopsy interview"
		"Trained field interviewers visited enrolled infants at home (or in health facilities for cases in which the mother and child were not discharged after delivery) 1 day and 3 days after dosing to monitor possible adverse events after supplementation"
		Comment: Most likely done
Incomplete outcome data (attrition bias)	Unclear risk	Total number of loss to follow up: n (%)
		The loss to follow up was not balanced
Selective reporting (reporting bias)	Low risk	Authors seem to report all the relevant outcomes
Other bias	Low risk	No other risk of bias was noted