Cherian 2003.

Study characteristics
Methods	Individually randomised trial conducted in Vellor, India
Participants	Eligibility: infants aged 9–12 months Excluded: children with history of measles vaccination or an exanthematous illness; with moderate or severe malnutrition; clinical signs of VAD; known immune deficiency or receiving immunosuppressive therapy; received blood or blood products in the previous 6 months Sample: 395 infants; 198 in vitamin A group, 197 in placebo group. Mean age 9.8 months. 52% boys
Interventions	Experimental group: single‐dose vitamin A 100,000 IU Control group: placebo Interventions provided at time of measles vaccination
Outcomes	Antibody response to measles vaccine
Notes	Primary objective of study was to measure the antibody response to measles vaccine when given with and without vitamin A. Study found no significant inhibitory or enhancing influence on antibody response to measles vaccine when administered concomitantly with vitamin A.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "The infants who were immunized with monovalent measles vaccine were randomly assigned, in blocks of eight, to concomitantly receive 100,000 IU of vitamin A in arachis oil or a placebo containing carboxymethylcellulose prepared in the hospital pharmacy". Comment: authors did not specify the method of sequence generation.
Allocation concealment (selection bias)	Low risk	Quote: "… arachis oil or a placebo containing carboxymethylcellulose prepared in the hospital pharmacy". Comment: probably done since hospital pharmacy was responsible for preparing the order of vitamin A and placebo, and unlikely to have been internal to the study team.
Blinding (performance bias and detection bias) Blinding of participants	Unclear risk	Quote: "… Vitamin A in arachis oil or a placebo containing carboxymethylcellulose …" Comment: insufficient information to permit judgement.
Blinding (performance bias and detection bias) Blinding of provider	Unclear risk	Comment: insufficient information to permit judgement.
Blinding (performance bias and detection bias) Blinding of outcome assessor	Unclear risk	Comment: insufficient information to permit judgement.
Incomplete outcome data (attrition bias)	High risk	Comment: the proportion of children providing adequate samples was low at 6 months, and there was insufficient detail about the reasons for missing data.
Selective reporting (reporting bias)	High risk	Comment: there was no mention of mortality or any morbidity of measles or diarrhoea.
Other bias	Unclear risk	Comment: insufficient information to permit judgement.