Benn 1997.

Methods	Individually‐randomised trial conducted in Belem and Mindra, 2 districts in Bissau, the capital of Guinea‐Bissau
Participants	Eligibility: infants aged 6‐9 months were eligible for inclusion in the trial. Those with signs of xerophthalmia, history of previous vitamin A supplementation, history of measles infection before 9 months of age, or who had a positive haemagglutinin‐inhibition assay (HIA) titre at 9 months of age were excluded. All infants reported to have had measles at 9‐18 months of age were also excluded. Sample: a total of 462 infants were randomised to either intervention or control group. The mean age of participants was 8.7 months, and proportion of boys was 51%.
Interventions	There were 3 study groups: Group I: included "infants aged 6 months and were randomly allocated to receive either a dose of measles vaccine at 6 months and a dose of measles vaccine at 9 months together with vitamin A supplement or the same dosing of measles vaccine with placebo as the supplement" Group II: consisted of "infants who were randomly allocated either poliomyelitis vaccine at 6 months and a single dose of measles vaccine at 9 months with vitamin A supplement or the same vaccine doings with a placebo as the supplement" Group III: included "infants who were older than 7·5 months at the beginning of the study or who were not found at home until they reached the age of 7·5 months, were included in the study at age 9 months and received a measles vaccine plus vitamin A or placebo supplement at that age" Vitamin A was supplemented in a single dose of 100,000 IU dissolved in 1 mL of vegetable oil along with 40 IU of vitamin E. The placebo was 40 IU of vitamin E dissolved in 1 mL of vegetable oil.
Outcomes	Antibody response to measles vaccine, all‐cause mortality, incidence of measles
Notes	The primary objective of the study was to calculate the antibody response to measles vaccine when given with vitamin A. The results for antibody response to measles vaccine showed no significant difference between the groups. The study concluded that simultaneous administration of measles vaccine and vitamin A has no negative effect on measles immunity. Similarly, vitamin A supplementation was shown to have no significant effect on immune response of CD4 and CD8 T‐cell in children without clinical vitamin A deficiency. Vitamin A or placebo was given only at 9 months of age in all 3 study groups. The only difference among the groups was the frequency and type of vaccine administered. We therefore added all the numbers for all 3 intervention and placebo groups to report the outcomes of interest to our review. We primarily took data from trial flow diagram and calculated the effect sizes accordingly.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The allocation sequence was computer generated."
Allocation concealment (selection bias)	Low risk	Quote: "The allocation sequence was kept in sealed envelopes and only released when all clinical laboratory analyses were completed."
Blinding (performance bias and detection bias) Blinding of Participants	Low risk	Quote: ". . .because of the young age of the participants, any difference in taste was irrelevant . . ." Comment: identical presentation; probably adequate
Blinding (performance bias and detection bias) Blinding of provider	Low risk	Quote: "None of the staff involved knew whether the bottles contained vitamin A or placebo . . ."
Blinding (performance bias and detection bias) Blinding of outcome assessor	Low risk	Quote: "None of the staff involved knew whether the bottles contained vitamin A or placebo . . ." Comment: masking of treatment group assignment and treatment to study personnel likely to have been maintained throughout.
Incomplete outcome data (attrition bias)	Low risk	Comment: number lost to follow‐up and those excluded were explicitly described and equal in both the groups. Loss to follow‐up exceeded the number of deaths and children with measles. Reasons for missing data (migration) probably unrelated to treatment
Selective reporting (reporting bias)	Low risk	Comment: some evidence of selective outcome reporting around malaria; however, deaths and prevalence of measles reported
Other bias	Unclear risk	Comment: authors report imbalance in self‐reported disease in the children aged 6 months at baseline. It is unclear how big an impact this will have had as the variable is not specific