The main objective is to assess the variation in plasma levels of cathelicidin before and after influenza vaccination. All bibliographic data suggests that supplementation vitamin D in the elderly often deficient in this vitamin may have a double interest: * By induction of cathelicidin, assist in anti-infective response in particular to the influenza virus * The normalization of vitamin D status, promote the return to an appropriate immune response limiting excess inflammation and improving capacity to respond. The entire project will collect new information on the merits of the use of vitamin D in aging. A better knowledge of mechanisms involved and the impact of aging on them is a necessary prerequisite the definition of a new strategy using this drug in the elderly particularly fragile in order to improve its autonomy. This definition seems a sociological interest obvious economic knowing the current aging population and its impact future of our health system.

CONDUCT OF THE STUDY: Visit 1: selection of subjects (CPC / CIC-Inserm CIC501) * Medical Examination, clinical examination, explanation of the protocol and collection of written consent, * Collection of anthropometric data measured size and not declarative weight form examination, measurement of current weight, BMI, waist circumference measurement. * Food Survey. * Fasting blood sampling: for dosing of vitamin D, cathelicidin, exploration of immunocompetent cells, calcium, phosphorus, urea and creatinine. Visit 2: randomization (CPC / CIC-Inserm CIC501) * Fasting blood sampling: for dosing of vitamin D, cathelicidin, and the serum calcium, phosphorus, urea and creatinine. * Exploration of immune cells in patients deficient in vitamin D (molecular and cellular analyzes). Start of vitamin D supplementation or placebo * Subjects with vitamin D levels \<30ng/mL will be randomized into two groups: * Arm receiving vitamin D (BS). * Arm receiving placebo (BC). * It will be given to the patient 4 bulbs product (vitamin D or placebo) for supplementation for 2 months (1 / 15 days). Call subjects at 4 weeks of vitamin supplementation / placebo to assess the clinical safety of the product, as well as compliance with the instructions of supplementation. Visit 3: After seven weeks of vitamin supplementation / placebo (CPC / CIC-Inserm CIC501) * Fasting blood assay for vitamin D and calcium collection. * urinary dosage calcium. Visit 4: Month 2 (CPC / CIC-Inserm CIC501) * Validation of laboratory measurements made by an independent medical M2 protocol. * Delivery of products to test for the third month of vitamin supplementation / placebo. For the placebo group given two bulbs for the third month placebo placebo supplementation. For the VitD group: dose adjustment according to the following scheme: * If \[25(OH) D\]\> 75 ng / ml and / or calcium levels\> 106 mg / ml and / or calcium excretion\> 300 mg / l: presentation of two bulbs placebo. * If \[25(OH) D\] \<75 ng / ml and serum calcium \<106 mg / ml and calcium excretion \<300 mg / l: presentation of two ampoules of Vitamin D. Visit 5 - Month 3 vaccination INTANZA 15 ® (3 months after the start of supplementation) * Recovery of boxes and empty ampoules of vitamin D. * Evaluation of the clinical safety of vitamin D. * Collection of anthropometric data: measurement of current weight and BMI, * Fasting blood sampling: for dosing of vitamin D, cathelicidin, exploration of immunocompetent cells, calcium, phosphorus, urea and creatinine. * Influenza serology, Visit 6 - Month 4: end of study * Clinical examination with assessment of tolerability of vaccination and delivery of the form of reporting due to immunization and infectious complications side effects according to the criteria of toxicity CTCNCI Bethesda, * Collection of anthropometric data: measurement of current weight, calculating the weight change, * Fasting blood sampling: for dosing of vitamin D, cathelicidin, exploration of immunocompetent cells, calcium, phosphorus, urea and creatinine. * Measurement of seroconversion, seroprotection, MGT antibodies following vaccination. End of the study Removal of anonymity for physician investigators to propose a vitamin D the subjects who received placebo.