2632. Cord Blood Vitamin D and Maternal Vaccination Status Associated with Decreased Laboratory Confirmed Influenza Infections in Infants

BACKGROUND: Maternal influenza vaccination has been demonstrated to reduce influenza infections in infants. Influenza infections generally peak during the winter season, and several studies support the association between low levels of vitamin D during winter months and an increase in respiratory infections, including influenza. We examined the effects of vitamin D and maternal influenza vaccination status on laboratory confirmed influenza infections in infants less than 6 months of age. METHODS: Pregnant Bangladeshi mothers were randomized to receive influenza vaccine or pneumococcal vaccine as part of the Mother’s Gift study. Mothers reported breastfeeding frequency, along with episodes of infant respiratory illness with fever, every week for the first 6 months of life. If a respiratory illness with fever was reported, nasal swabs were obtained from the infant and tested with a commercial rapid influenza test. Infants with confirmed influenza disease were matched with four controls by birth month and sex, for a total of 84 controls. We measured 25-hydroxyvitamin D levels from cord blood in all cases and controls. A conditional logistic regression was performed to test the effect of vitamin D on the odds of laboratory confirmed influenza while controlling for birth weight, gestational age, crowding, number of siblings, and socioeconomic status score. RESULTS: A total of 21 infants had laboratory confirmed influenza disease. There were no significant differences in birth weight, crowding, family size, gestational age, socioeconomic status score, infant gender, and smokers in the home between cases and controls (Table 1). Frequency of maternal influenza vaccine was lower in cases when compared with controls (23.81% vs. 58.33%). Serum vitamin D was lower in cases than in controls (8.73 ± 3.34 vs. 10.67 ± 4.08, Table 2). CONCLUSION: Both vitamin D levels and maternal vaccination status have medically relevant, and statistically significant, independent effects on the odds of infants contracting influenza. Although the vitamin D levels in the infants at birth were low, there was a significant association of lower levels at birth with an increased risk of influenza virus infection. Further study with a larger sample-size is needed to explore these effects. [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.