Study of RSVpreF Vaccination and RSV Challenge in Healthy Adults

Inclusion Criteria

• An informed consent document signed and dated by the participant and the Investigator.
• Aged between 18 and 50 years.
• In good health with no history, or current evidence, of clinically significant medical conditions, and no clinically significant test abnormalities that will interfere with participant safety.
• A documented medical history prior to enrolment.
• The following criteria are applicable to female participants participating in the study.
• Females of childbearing potential must have a negative pregnancy test prior to enrolment.
• Females of non-childbearing potential:
• Post-menopausal females; defined as having a history of amenorrhea for >12 months with no alternative medical cause, and /or by FSH level >40mIU/mL, confirmed by laboratory.
• Documented status as being surgically sterile (e.g. tubal ligation, hysterectomy, bilateral salpingectomy and bilateral oophorectomy).
• The following criteria apply to female and male participants:
• Female participants of childbearing potential must use one form of highly effective contraception. Hormonal methods must be in place from at least 2 weeks prior to the first study visit. The contraception use must continue until 28 days after the date of viral challenge/last dosing with IMP (whichever occurs last).
• Male participants must agree to the contraceptive requirements below at entry to quarantine and continuing until 28 days after the date of Viral challenge / last dosing with IMP (whichever occurs last): a. Use a condom with a spermicide to prevent pregnancy in a female partner or to prevent exposure of any partner (male and female) to the IMP. b. Male sterilisation with the appropriate post vasectomy documentation of the absence of sperm in the ejaculate (please note that the use of condom with spermicide will still be required to prevent partner exposure). This applies only to males participating in the study. c. In addition, for female partners of child bearing potential, that partner must use another form of contraception such as one of the highly effective methods mentioned above for female participants.

In addition to the contraceptive requirements above, male participants must agree not to donate sperm following discharge from quarantine until 28 days after the date of Viral Challenge/last dosing with IMP (whichever occurs last).

• True abstinence - sexual abstinence is considered a highly effective method only if defined as refraining from heterosexual intercourse during the entire period of risk associated with the study treatments. The reliability of sexual abstinence needs to be evaluated in relation to the duration of the clinical trial and the preferred and usual lifestyle of the participant.
• Sero-suitable to the challenge virus.

Exclusion Criteria

• History of, or currently active, symptoms or signs suggestive of upper or lower respiratory tract infection within 4 weeks prior to the first study visit.
• a) Any history or evidence of any other clinically significant or currently active systemic comorbidities including psychiatric disorders (includes participants with a history of depression and/or anxiety).

b) And/or other major disease that, in the opinion of the Investigator, may put the participant at undue risk, or interfere with a participant completing the study and necessary investigations (e.g autoimmune disease or immunodeficiency).

• Participants who have smoked ≥ 10 pack years at any time [10 pack years is equivalent to one pack of 20 cigarettes a day for 10 years].
• A total body weight ≤ 50 kg and Body Mass Index (BMI) ≤18 kg/m2 and ≥30kg/m2.
• Females who:
• Are breastfeeding, or
• Have been pregnant within 6 months prior to the study.
• History of anaphylaxis-and/or a history of severe allergic reaction or significant intolerance to any food or drug or vaccine, including hypersensitivity to any of the constituents of the study vaccine, as assessed by the PI.
• Venous access deemed inadequate fo