Extension Study to Evaluate the Safety and Immunogenicity of a Revaccination Dose of the RSVPreF3 OA Investigational Vaccine in Adults 60 Years and Older Who Participated in the RSV OA=ADJ-002 Study

Inclusion Criteria: * Male or female participants, who received 2 doses of RSVPreF3 OA investigational vaccine and formulations with matched adjuvant in part B of the parent study RSV OA=ADJ-002: recombinant RSVPreF3 antigen doses of low, medium and high strengths with adjuvant. * 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 the follow-up visit, be available for contact) * Written informed consent obtained from the participant prior to performance of any study specific procedure. Exclusion Criteria: Medical conditions * Significant underlying illness or administered therapy that in the opinion of the investigator would be expected to prevent participation in the study. * Any confirmed or suspected immunosuppressive or immunodeficient condition based on information on concomitant medication/vaccination collected prior to the study start and physical examination. * Serious or unstable chronic illness that developed during or after the parent study. Patients with chronic stable medical conditions with or without specific treatment, such as diabetes, hypertension or cardiac disease, are allowed to participate in this study if considered by the investigator as clinically stable. * Recurrent or un-controlled neurological disorders or seizures that developed during or after the parent study. Participants with medically-controlled active or chronic neurological diseases can be enrolled in the study as per investigator assessment, provided that their condition will allow them to comply with the requirements of the protocol. * Significant underlying illness that developed during or after the parent study, that in the opinion of the investigator would be expected to prevent completion of the study. * Lymphoproliferative disorder and malignancy developed during or after the parent study. * Any medical condition that developed during or after the parent study, that in the judgment of the investigator would make intramuscular injection unsafe. * Previous vaccination with RSV vaccine, other than the one in the parent study. Prior/Concomitant therapy * Use of any investigational or non-registered product (drug, vaccine or medical device) other than the study vaccine during the period beginning 30 days before the dose of study vaccine, or planned use during the study period. * Planned or actual administration of a vaccine not foreseen by the study protocol in the period starting 30 days before and ending 30 days after the dose of study vaccine administration, with the exception of inactivated, split virion and subunit influenza vaccines which can be administered up to 14 days before or from 30 days after the study vaccination. * Administration of long-acting immune-modifying drugs or planned administration at any time during the study period. * Administration of immunoglobulins and/or any blood products or plasma derivatives during the period starting 90 days before the dose of study vaccine or planned administration during the study period. * Chronic administration (defined as more than 14 consecutive days in total) of immunosuppressants or other immune-modifying drugs during the period starting 90 days prior to the vaccine dose or planned administration during the study period. For corticosteroids, this will mean prednisone ≥20 mg/day, or equivalent. Inhaled and topical steroids are allowed. * Confirmed use or anticipated use of immunosuppressive/cytotoxic therapy. Prior/Concurrent clinical study experience • Concurrently participating in another clinical study, at any time during the study period, in which the participant has been or will be exposed to an investigational or a non-investigational vaccine/product. Other exclusions * Bedridden participants. * Planned move to a location that will prohibit participating in the trial. * History of chronic alcohol consumption and/or drug abuse that developed during or after the parent study as deemed by the investigator to render the potential participant unable/unlikely to provide accurate safety reports or comply with study procedures.