A Study to Evaluate the Reactogenicity, Safety and Immunogenicity of GlaxoSmithKline (GSK) Biologicals' Investigational Supra-seasonal Universal Influenza Vaccines - Inactivated (SUIVs) (GSK3816302A) in Healthy Adults Aged 18 to 39 Years

Current seasonal influenza vaccines show good efficacy when they are well-matched with the
circulating virus strains.

However, influenza viruses constantly change their surface glycoproteins that are the targets
of most immune responses, allowing them to escape pre-existing immunity, a process called
antigenic drift. Therefore, seasonal influenza vaccines have to be reformulated and
re-administered on an annual basis. In addition, novel viruses can appear at irregular
intervals and cause influenza virus pandemics that can claim millions of lives.

GSK Biologicals is now developing a new influenza vaccine that contains modified inactivated
influenza viruses. The purpose of this approach is to elicit an immune response that would
protect against all current and future circulating influenza strains without having to
administer the vaccine each year.

Inclusion Criteria:

- 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 performance of any study
specific procedure.

- A male or female between, and including, 18 and 39 years of age at the time of the
first vaccination.

- Healthy subjects without acute or chronic, clinically significant pulmonary,
cardiovascular, hepatic or renal functional abnormality, as established by medical
history and clinical examination before first vaccination and laboratory screening
tests (the latter being only applicable for subjects enrolled in Phase I).

- Subjects with no history of influenza vaccination within 6 months prior to first study
vaccination and who are willing to forego any influenza vaccination during the entire
study period.

- Female subjects of childbearing potential may be enrolled in the study, if the
subject:

- Has practiced adequate contraception for 30 days prior to first 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 (last vaccination at
Month 14).

Exclusion Criteria:

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

- Any medical condition that in the judgment of the investigator would make
intramuscular 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. Topical steroids are allowed.

- Administration of long-acting immune-modifying drugs within 6 months before first
vaccination, or planned administration 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 up to the blood sampling at Day
85 and in the period starting 30 days before booster vaccination at Month 14 up to the
blood sample at Month 14 + 28 days.

- 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.

- Previous vaccination against influenza within the 6 months preceding the first
vaccination at Visit 1 or planned use of such vaccines during the study period.

- History of vaccination with a (pre)pandemic influenza vaccine other than an H1N1pdm09
vaccine or history of laboratory-confirmed influenza infection other than seasonal or
H1N1pdm09 influenza.

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

- History of or current autoimmune disease.

- Subjects diagnosed with excessive daytime sleepiness or narcolepsy; or history of
narcolepsy in a subject's parent or sibling.

- History of Guillain-Barré syndrome.

- History of any reaction or hypersensitivity likely to be exacerbated by any component
of the vaccines; a history of anaphylactic-type reaction to consumption of eggs; or a
history of severe adverse reaction to a previous influenza vaccine.

- Hypersensitivity to latex.

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

- Fever is defined as temperature ≥ 38.0°C / 100.4°F. The preferred location for
measuring temperature in this study will be the oral cavity.

- Subjects with a minor illness without fever may be enrolled at the discretion of
the investigator.

- For subjects with acute disease and/or fever at the time of enrolment, Visit 1
may be re-scheduled within the allowed time-window.

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

- Blood donation within 30 days before the first study blood sampling or planned blood
donation within 30 days before and up to 30 days after any study blood sampling.

- Pregnant or lactating female.

- 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.

- Female planning to become pregnant or planning to discontinue contraceptive
precautions.

- Any condition that puts the subject at risk for serious influenza-related
complications, as identified by the Advisory Committee on Immunization Practices
[Grohskopf, 2017] (note that only criteria applicable for the study population are
listed below):

- Chronic pulmonary (including asthma), cardiovascular (except isolated hypertension),
renal, hepatic, neurologic, hematologic or metabolic disorders (including diabetes
mellitus);

- Persons who are immunocompromised due to any cause (including immunosuppression caused
by medications or by HIV infection);

- Adolescents (through 18 years) who are receiving aspirin- or salicylate-containing
medications and who might be at risk for experiencing Reye syndrome after influenza
virus infection;

- Residents of nursing homes and other long-term care facilities;

- American Indians/Alaska Natives; and

- Persons who are extremely obese (Body Mass Index ≥ 40).

Additional criterion applicable for Phase I subjects:

- Hematological and/or biochemical parameters outside the laboratory normal ranges,
unless the laboratory abnormalities are considered not clinically significant by the
investigator.

- Liver enzymes (alanine aminotransferase [ALT] or aspartate aminotransferase [AST])
outside of the normal laboratory ranges.