Children between the ages of 1 and 4 years old (inclusive) will be enrolled. All will receive PCV and hepatitis A vaccination. Those randomized to the treatment arm will receive 10,000 IU orally at the time of vaccination, while those randomized to the control arm will only receive vaccines. Vitamin levels and antibody responses towards the vaccines will be measured at screening, Day 0 (vaccination day) and Day +21. Children will be randomized using a stratified permuted block method.
