500 subjects (thereof, 250 aged 50 - 64 years and 250 aged 65 years and older) will be randomized in a 3:3:3:1 ratio to receive either VLA84 75 µg w/o Alum, VLA84 200 µg w/o Alum, VLA84 200 µg w/ Alum (150 subjects each), or placebo (50 subjects). Vaccinations consist of two i.m. injections administered in close proximity to each other in the deltoid region at Day 0, 7 and 28, starting with the non-dominant arm and alternating arms between the vaccination days.