FCGR2A and influenza: In sub-study (ii), to assess the durability (versus day 0 baseline, day 30 (post-vaccination, 2009) at 1 year follow up in 2010, 2011, 2012, 2013, 2014) of seasonal vaccine stimulated antibody responses (IgG, IgG1, IgG2, IgG3, IgA, FcγR3a and FcγR2a as detectors) for seasonal and influenza proteins (H1 (sH1), pH1, sH3, H1-stem, pN1, sN1, M1 and NP) by multiplex approach.