Safety, Immunogenicity and Efficacy of GSK S. Aureus Candidate Vaccine (GSK3878858A) When Administered to Healthy Adults (Dose-escalation) and to Adults 18 to 64 Years of Age With a Recent S. Aureus Skin and Soft Tissue Infection (SSTI)

Inclusion Criteria: All participants must satisfy all the following criteria at study entry: * Participants who, in the opinion of the investigator, can and will comply with the requirements of the protocol (e.g. completion of the diary cards, return for follow-up visits). * Written or witnessed informed consent obtained from the participant prior to performance of any study specific procedure. * Participant satisfying screening requirements. * Participants who, after the nature of the study has been explained to them, have shown adequate comprehension of the study procedures and knowledge of study. * A male or female * Dose escalation and safety lead-in phase: Aged between 18 and 50 years of age, inclusive, at the time of first vaccination. * PoP phase: Aged between 18 and 64 years of age, inclusive, at the time of first vaccination. * Female participants of non-childbearing potential may be enrolled in the study. Non-childbearing potential is defined as pre-menarche, current bilateral tubal ligation or occlusion, hysterectomy, bilateral ovariectomy or post-menopause. * Female participants of childbearing potential may be enrolled in the study, if the participant: * has practiced adequate contraception for 30 days prior to vaccination, * has a negative pregnancy test on the day of enrolment, and * has agreed to continue adequate contraception during the entire treatment period and for 2 months after completion of the vaccination series. Additional inclusion criteria only …