1) To determine whether ZOSTAVAX™ administered concomitantly with influenza vaccine in subjects 50 years of age or older elicits a VZV antibody response that is noninferior to that of ZOSTAVAX™ administered alone. 2) To demonstrate whether ZOSTAVAX™ elicits an acceptable VZV antibody response when administered concomitantly with influenza vaccine in subjects 50 years of age or older. 3) To assess whether influenza vaccine administered concomitantly with ZOSTAVAX™ in subjects 50 years of age or older elicits strain-specific influenza antibody responses that are noninferior to those of influenza vaccine administered alone.