Efficacy Study of GSK's Investigational Respiratory Syncytial Virus (RSV) Vaccine in Adults Aged 60 Years and Above

This study will evaluate the efficacy of the RSVPreF3 OA investigational vaccine in preventing Lower Respiratory Tract Disease (LRTD) caused by RSV in adults ≥60 years of age following a single dose of the RSVPreF3 OA vaccine and following annual revaccination doses in Northern Hemisphere (NH) and in Southern Hemisphere (SH). This study will also assess if the vaccine is safe and induces an immune response.

Dose 1 Period will be conducted in 2 parts: Part 1: Participants in RSVPreF3 groups will receive lots 1, 2 and 3 of the investigational vaccine before Season 1. Part 2: Will be initiated when the vaccine lots in part 1 are exhausted at the study sites and participants in RSVPreF3 group will receive lot 4 of the investigational vaccine before Season 1.

Eligibility Criteria:
Inclusion Criteria:

* A male or female ≥ 60 YOA at the time of first vaccination, who live in the community (community dwelling participants) or in a long-term care facility (LTCF participants).
* Participants who, in the opinion of the investigator, can and will comply with the requirements of the protocol.

Note: In case of physical incapacity that would preclude the self-completion of the diary cards and/or questionnaires, either site staff can assist the participant (for activities performed during site visits) or the participant may assign a caregiver to assist him/her with this activity (for activities performed at home or in the LTCF). However, at no time, the site staff or caregiver will evaluate the participant's health status while answering diaries and/or questionnaires or make decisions on behalf of the participant

* 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 first vaccination. Participants 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 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 vaccine.
* Hypersensitivity to latex.
* Serious or unstable chronic illness.
* Any history of dementia or any medical condition that moderately or severely impairs cognition.

Note: If deemed necessary for clinical evaluation, the investigator can use tools such as Mini-Mental State Exam (MMSE), Mini-Cog or Montreal Cognitive Assessment (MoCA) to determine cognition levels of the participant.

* Recurrent or un-controlled neurological disorders or seizures. Participants with medically-controlled active 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 vaccine during the period beginning 30 days before the first study vaccine 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 each dose and ending 30 days after each dose of study vaccine administration, with the exception of inactivated and subunit influenza vaccines which can be administered up to 14 days before or from 14 days after each study vaccination.
* 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 first 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 first study vaccine 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 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.
* Bedridden participants.
* Planned move during the study period that will prohibit participating in the trial until study end. This includes:

  * Planned move during the study period to another LTCF that will prohibit participation in the trial until study end.
  * Planned move from the community to a LTCF that will prohibit participation in the trial until study end.
* Participation of any study personnel or their immediate dependants, family, or household members.
* Planned leave or holiday of 4 consecutive weeks or more during the RSV seasons\* covered by the study, that would prohibit the reporting of ARI cases and attendance to ARI visit.

  * RSV seasons are from October to April in NH and from March to September in SH.