A Study to Assess the Safety, Reactogenicity and Immune Response of GlaxoSmithKline (GSK) Biologicals' Investigational Respiratory Syncytial Virus (RSV) Vaccine (GSK3844766A) in Older Adults

Inclusion Criteria:

For all subjects:

- Subjects who, in the opinion of the investigator, can and will comply with the
requirements of the protocol.

- Written informed consent obtained from the subject prior to performing any study
specific procedure.

For Part A:

• A male or female between, and including, 18 and 40 years of age at the time of the first
vaccination.

For Part B:

- A male or female between, and including, 60 and 80 years of age at the time of the
first vaccination.

- Subjects with residence status allowing free mixing with general community or in an
assisted-living facility that provides minimal assistance, such that the subject is
primarily responsible for self-care and activities of daily living.

Exclusion Criteria:

For all subjects:

- Use of any investigational or non-registered product other than the study vaccine
during the period starting 30 days before the first dose of study vaccine, or planned
use during the study period.

- Any medical condition that in the judgment of the investigator would make IM injection
unsafe.

- Chronic administration of immunosuppressants or other immune-modifying drugs during
the period starting 6 months prior to the first vaccine dose. For corticosteroids,
this will mean prednisone (≥ 20 mg/day, or equivalent). Inhaled and topical steroids
are allowed.

- Administration of long-acting immune-modifying drugs or planned administration at any
time during the study period.

- Planned administration/administration of a vaccine not foreseen by the study protocol
in the period starting 30 days before the first dose and ending 30 days after the last
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 30 days
after each study vaccination.

- Concurrently participating in another clinical study, at any time during the study
period, in which the subject has been or will be exposed to an investigational or a
non-investigational vaccine/product.

- Any confirmed or suspected immunosuppressive or immunodeficient condition, based on
medical history and physical examination.

- History of any reaction or hypersensitivity likely to be exacerbated by any component
of the vaccine.

- Hypersensitivity to latex.

- Serious or unstable chronic illness. Patients with chronic stable conditions with or
without specific treatment, such as diabetes, hypertension or cardiac disease, are
allowed to participate in this study.

- Any other condition (e.g. chronic obstructive pulmonary disease or severe respiratory
condition) that, in the opinion of the investigator, might interfere with the
evaluations required by the study.

- History of any neurological disorders or seizures.

- Acute disease and/or fever at the time of enrolment.

- Acute or chronic, clinically significant pulmonary, cardiovascular, hepatic or renal
functional abnormality, as determined by the investigator based on medical history,
physical examination or laboratory screening tests.

- Hepatomegaly, right upper quadrant abdominal pain or tenderness.

- Administration of immunoglobulins and/or any blood products during the period starting
3 months before the first dose of study vaccine or planned administration during the
study period.

- History of chronic alcohol consumption and/or drug abuse as deemed by the investigator
to render the potential subject unable/unlikely to provide accurate safety reports.

- Significant underlying illness that in the opinion of the investigator would be
expected to prevent completion of the study.

- Previous vaccination with an RSV vaccine.

- Lymphoproliferative disorder and malignancy within 5 years.

- Body mass index > 40 kg/m².

- Planned move to a location that will prohibit participating in the trial until study
end.

- At screening: Hematology parameters (complete blood cell count [red blood cells, white
blood cells], white blood cells differential count [lymphocytes, neutrophils and
eosinophils], platelets count or hemoglobin level) and/or biochemistry parameters
(creatinine, blood urea nitrogen or liver enzymes [alanine aminotransferase or
aspartate aminotransferase]) outside the normal laboratory ranges, unless the
laboratory abnormalities are considered not clinically significant by the
investigator.

For Part A:

- Pregnant or lactating female.

- Female subjects of childbearing potential, except if the subject:

- has practiced adequate contraception for 30 days prior to vaccination, and

- has a negative pregnancy test on the day of vaccination, and

- has agreed to continue adequate contraception during the entire treatment period
and for 2 months after completion of the vaccination series.

For Part B:

- Known previous administration of a vaccine containing MPL, QS-21 and/or MF59 (e.g. GSK
Biologicals' vaccine against human papillomavirus infection marketed as Cervarix, GSK
Biologicals' Herpes Zoster vaccine marketed as Shingrix, an adjuvanted recombinant
varicella zoster virus envelope gE subunit vaccine [HZ/su], or MF59 adjuvanted
influenza vaccines [e.g. Fluad]).

- Planned administration of GSK Biologicals' Herpes Zoster vaccine marketed as Shingrix
or an adjuvanted recombinant varicella zoster virus envelope gE subunit vaccine
[HZ/su] within 180 days after the second dose of the study vaccine.

- Bedridden subjects.