The purpose of the RSV F-021 study that will be conducted in an observer-blind manner during Epoch 1 and single blinded during Epoch 2, is to rank the 3 different doses of the non-adjuvanted investigational RSV PreF-vaccine (30, 60 and 120 μg) based on safety/reactogenicity and immunogenicity data up to 1 month post-vaccination (Day 30). Non-pregnant women aged 18-45 years will be randomized in a 1:1:1:1 ratio to receive one of three dose levels (30, 60, 120 μg) of the RSV PreF vaccine or placebo. The doses eliciting strong immune responses while maintaining an acceptable safety profile will be considered for further evaluation, including in studies vaccinating pregnant women. This will allow evaluation of a wider antigen dose range to determine if there is a dose response relationship in terms of antibody response at the higher dose range that was not present at the lower range.~Since in RSV F-021 the 120ug dosage of the PreF-based investigational RSV vaccine will be tested for the first time in humans, appropriate safety monitoring is planned for this study, including pausing enrolment when the first 25% of subjects from each study group have been vaccinated until review of day 7 post-vaccination safety data by an unblinded GSK internal Safety Review Committee (iSRC) has been completed. The enrolment/vaccination of the remaining subjects can only start following the favourable outcome of this iSRC safety review.~In addition to study visits at Day 0, Day 7 and Day 30 to evaluate primary objective of the study, additional study visits are planned at Day 60 and 90 for further investigation of the immunogenicity and safety/reactogenicity profile of the formulations. A follow-up period has been set up in which the subjects will be contacted at Day 180, 270 and 360. During these contacts, the investigator (or delegate) will ask the subject if she has experienced any serious adverse events and/or any AEs leading to study withdrawal since Day 90/last contact (as applicable), as well as if she has become pregnant during the post-vaccination period. The investigator (or delegate) will also ask the subject about concomitant vaccinations/products/medications that she has received since Day 90/last contact (as applicable) and whether the she had a respiratory tract infection that needed medical attention. Contact should be preferably performed via telephone, or alternatively, if phone contact is not possible, through email/other means where the information can be fully collected.~Healthy, non-pregnant women aged 18 - 45 years will be enrolled in this study:~Women aged 18 - 45 years are selected to match the vaccine's target population, i.e. pregnant women, as closely as possible (gender, age).~Non-pregnant women are selected to avoid unnecessarily exposing a vulnerable population (pregnant women and the foetuses/children) to a higher dose of the vaccine that has not previously been studied in non-pregnant women.
The purpose of this study is to rank different RSV vaccine dosages of antigen (or formulations) based on safety/reactogenicity and immune response data. The formulations eliciting strong immune responses while maintaining an acceptable safety profile will be considered for further evaluation, including in studies vaccinating pregnant women.