A Phase III, Randomized, Open-label, Active Vaccine-controlled Crossover Study to Evaluate the Reactogenicity, Safety and Immune Response of Unadjuvanted RSV Maternal Vaccine in Healthy Non-pregnant Girls From 9 to 17 Years of Age, and in Non-pregnant Adult Women From 18 to 49 Years of Age

Single dose of the RSV MAT vaccine reconstituted with NaCl solution was planned to be administered intramuscularly, in the non-dominant arm, at Day 1 or at Day 31, depending on the vaccination schedule. RSV MAT vaccine was no longer administered to participants at Day 31. No vaccine was administered in the dTpa\_RSV-P Group, since there were no participants assigned to it.

Single dose of the dTpa vaccine was planned to be administered intramuscularly, in the non-dominant arm, at Day 1 or at Day 31, depending on the vaccination schedule. Two formulations of dTpa vaccine are licensed in the US and outside of the US (ex-US), respectively. dTpa-US formulation was administered to participants in centers located in the US, while dTpa-ex-US formulation was planned to be administered to participants in centers ex-US. The dTpa-ex-US formulation was not applicable in this study anymore as no non-US sites were initiated before the decision to stop the study. The participants in RSV\_dTpa-P and RSV\_dTpa-A study groups were provided with an option to decide to receive dTpa vaccination as part of standard of care/local recommendation on immunization. No vaccine was administered in the dTpa\_RSV-P Group, since there were no participants assigned to it.