Confirmatory Phase II/III Study Assessing Efficacy, Immunogenicity and Safety of IC43

This is a confirmatory, randomized, placebo-controlled, multi-center, double-blinded phase II/III study. The study population consists of male or female intensive care unit (ICU) patients with a need for mechanical ventilation for more than 48 hours, aged between 18 and 80 years. Eight-hundred patients will be enrolled at approximately 50 study centers. Informed consent (i.e., from the patient or from the patient's legally authorized representative) or waiver will be obtained according to regional requirements prior to any study related procedures. Patients will be randomized to receive either IC43 100 mcg or placebo and will receive the first vaccination on Day 0. The second vaccination will be applied on Day 7. In case ICU discharge occurs before Day 7, immunization will be done at the hospital ward.