The investigators want to compare the T- and B-cell response to conventional intramuscular trivalent influenza vaccine (TIV) in elderly individuals dependent on the presence and duration of CMV infection by analyses of vaccine-induced plasmablasts, antibodies and antigen-specific T cells. Healthy volunteers, > 60 years of age, will be identified by the Stanford Blood Center based on their history of positive or negative CMV serologies. Baseline blood samples will be drawn from all study participants prior to immunization. All participants will receive a single dose of 2012-2013 licensed TIV. Volunteers will complete 3 study visits at Day 0, Day 7 and Day 28.