- Cohort 2: A second cohort of one hundred subjects (100) subjects will be randomized; of these, fifty six (56) will be dosed with the medium dose of the quadrivalent VLP vaccine, nineteen (19) be dosed with the high dose of the quadrivalent VLP vaccine, and twenty five (25) will receive a placebo. The 7-day safety data after the immunization will be collected and reviewed by the DSMB, prior to permitting immunization with the highest dose.