Baseline and background characteristics of the study population.

The percentage is given as the proportion of the reference population. OPV: Oral polio vaccine. MUAC: Mid-upper arm circumference. For the anthropometric measures (age, weight, length and MUAC) the mean (standard deviation) are given. The p-value designating the significance level of the difference between the randomization groups for either sex is obtained by χ2-test for categorical variables, and t-test for continuous variables. *Statistical test of distribution of all four vitamin A categories.