The purpose of this study is to assess the lot-to-lot consistency in terms of immunogenicity and evaluate the safety and reactogenicity of 3 lots of the RSVPreF3 OA investigational vaccine administered as a single dose in adults ≥ 60 years of age (YOA).

Inclusion Criteria:

• Participants who, in the opinion of the investigator, can and will comply with the requirements of the protocol. A male or female ≥ 60 YOA at the time of first study intervention administration.
• Participants living in the general community or in an assisted living facility that provides minimal assistance, such that the participant is primarily responsible for self care and activities of daily living.
• Written or witnessed informed consent obtained from the participant prior to performance of any study specific procedure.
• Participants who are medically stable in the opinion of the investigator at the time of vaccination. Participants with chronic stable medical conditions with or without specific treatment, such as diabetes, hypertension or cardiac disease, can participate in this study if considered by the investigator as medically stable.

Exclusion Criteria:

Medical conditions

• Any confirmed or suspected immunosuppressive or immunodeficient condition resulting from disease or immunosuppressive/cytotoxic therapy, based on medical history, and physical examination (no laboratory testing required).
• History of any reaction or hypersensitivity likely to be exacerbated by any component of the study intervention(s).
• Hypersensitivity to latex.
• Serious or unstable chronic illness.
• Any history of dementia or any medical condition that moderately or severely impairs cognition.
• Recurrent or un controlled neurological disorders or seizures. 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 in the opinion of the investigator would be expected to prevent completion of the study.
• Any medical condition that in the judgment of the investigator would make intramuscular injection unsafe.

Prior/Concomitant therapy

• Use of any investigational or non registered product (drug, vaccine or medical device) other than the study intervention(s) during the period beginning 30 days before study intervention administration and ending 30 days after study intervention administration, 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 study intervention administration, with the exception of inactivated and subunit influenza vaccines which can be administered up to 14 days before or from 14 days after the study vaccination.
• Note: In case an emergency mass vaccination for an unforeseen public health threat (e.g. a pandemic) is recommended and/or organized by the public health authorities, outside the routine immunization program, the time period described above can be reduced if necessary for that vaccine provided it is used according to the local governmental recommendations and that the Sponsor is notified accordingly. Previous vaccination with an RSV vaccine.
• 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 administration of the study intervention 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 study intervention administration or planned administration during the study period. For corticosteroids, this will mean prednisone ≥ 20 mg/day or equivalent. Inhaled and topical steroids are allowed.

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 (drug or invasive medical device).

Other exclusions

• History of chronic alcohol consumption and/or drug abuse as deemed by the investigator to render the potential participant unable/unlikely to provide accurate safety reports or comply with study procedures.
• Planned move during the study period that will prohibit participating in the study until study end.
• Bedridden participants.
• Participation of any study personnel or their immediate dependents, family, or household members.

IPD for this study will be made available via the Clinical Study Data Request site.

IPD will be made available within 6 months of publishing the results of the primary endpoints, key secondary endpoints and safety data of the study.

Access is provided after a research proposal is submitted and has received approval from the Independent Review Panel and after a Data Sharing Agreement is in place. Access is provided for an initial period of 12 months but an extension can be granted, when justified, for up to another 12 months.

Study is double blind from start to final analysis after which the study is considered single blind.