Each year 1.5 million children under the age of 5 years die from pneumonia. In the United States, respiratory syncytial virus (RSV) is the number one cause of bronchiolitis and pneumonia in children under 1 year of age. Low serum 25(OH)D is associated with an increased risk of lower respiratory tract infections (LRTI). Two recent studies have provided important information concerning the association between cord blood 25(OH)D and subsequent risk of developing respiratory infection in very young children. These findings support the need in future studies to determine the extent to which an intervention to change the vitamin D status of mothers during pregnancy can reduce the risk of RSV-associated LRTI in their offspring. An answer to this question would have significant worldwide public health importance given the high prevalence of low vitamin D status worldwide and the high mortality burden accompanying infectious lung diseases in young children.