Dose, Safety and Pathogenicity of SARS-CoV-2 (COVID-19) Omicron Virus (BA.5)

Inclusion Criteria: * Written informed consent * Adult male or female aged between 18 and 40 years * A total body weight ≥50 kg and body mass index (BMI) ≥18 kg/m2 and ≤28kg/m2. The upper limit of BMI may be increased to ≤30kg/m2 at the PI's discretion, in the case of physically fit muscular individuals. * 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. * Documented medical history * Adherence to contraception requirements * Serosuitable for the challenge virus * Participants must have been previously vaccinated with a COVID-19 vaccine licensed for use in the UK and completed the course Exclusion Criteria: * History of, or currently active, symptoms or signs suggestive of upper or lower respiratory tract (LRT) infection within 4 weeks prior to the first study visit. * Any history or evidence of any clinically significant or currently active disease. * Any participants who have smoked ≥5 pack years at any time. * Female participants who are breastfeeding, or have been pregnant within 6 months prior to the study, or have a positive pregnancy test at any point during screening or prior to inoculation. * Any history of anaphylaxis and/or a any history of severe allergic reaction. * Venous access deemed inadequate for the phlebotomy and cannulation demands of the study. * History of severe COVID-19 or severe complication of any other viral disease. * Participants with no knowledge of their family history, as deemed appropriate by the PI * Significant abnormality of the nose, includes loss of or alterations in smell or taste,nasal polyps, epistaxis, nasal or sinus surgery. * Recent vaccinations or intention to receive vaccination before the Day 28 follow up visit. Receipt of COVID-19 vaccine in the last 3 months prior to inoculation and/or a diagnosis of COVID 19 confirmed by a physician within the last 6 months prior to screening or at any time between screening and quarantine admission. * Receipt of blood or blood products, or loss (including blood donations) of 550 mL or more of blood during the 3 months prior to the planned inoculation or planned during the 3 months after the final visit. * Recent receipt of investigational drugs or challenge viruses. * Use or anticipated use during the conduct of the study of concomitant medications (prescription and/or non-prescription), including vitamins or herbal and dietary supplements within the specified windows. * Positive drugs of abuse test or recent history or presence of alcohol addiction * A forced expiratory volume in 1 second (FEV1) \<80%. * Positive HIV, hepatitis B virus, or hepatitis C virus test. * Presence of fever, defined as participant presenting with a temperature reading of ≥37.9°C on Day -2/-1 and/or pre-inoculation on Day 0. * Those employed or immediate relatives of those employed at hVIVO or the sponsor. * Any other reason, in the opinion of the investigator deems the participant unsuitable for the study * Sensitivity to any of the study interventions, challenge agent or components thereof (including lactose), or drug or other allergy that, in the opinion of the PI/investigator, contraindicates participation in the study.