Influenza viral infection can cause serious illness among young infants 0-6 months of age. However, inactivated influenza vaccine is not recommended for this age group but pregnant women can be vaccinated during 2nd - 3rd trimester to induce passive immunization of their infants. Nevertheless vitamin A deficiency is highly prevalent among pregnant women in Bangladesh, >50% pregnant women consume less vitamin A than the recommended level. Given the fact that both clinical and sub-clinical vitamin A deficiency impair vaccine specific immunity, in this proposed study, we aim to investigate whether maternal vitamin A supplementation improve influenza vaccine specific immune responses among pregnant women and the passive protection of their infants.

In a placebo controlled clinical trial, sixty six mothers will be randomly assigned to receive either 10,000 IU vitamin A or placebo capsules weekly from second trimester to 6 month postnatal period. At 26-28 weeks of gestation, all mothers will be vaccinated with inactivated, trivalent influenza virus vaccine. Maternal and cord blood will be collected for vitamin A and influenza virus specific IgG assessment. Colostrum and breast milk at 6-month will be collected for vitamin A and influenza virus specific secretory IgA assessment. Venous blood (2-3 ml) will be obtained from all infants at the age of 6 months for vitamin A and influenza virus specific IgG assessment as well as infants' nasal swab for influenza virus specific secretory IgA.