Dose, Safety, and Pathogenicity of a New Influenza B Strain

Inclusion Criteria: * Written informed consent * Adult male or female aged between 18 and 55 years * A total body weight ≥50 kg and body mass index (BMI) ≥18 kg/m2 and ≤35kg/m2 * 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. 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 ≥10 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. * Lifetime history of anaphylaxis and/or a lifetime history of severe allergic reaction. * Venous access deemed inadequate for the phlebotomy and cannulation demands of the study. * Significant abnormality of the nose, epistaxis, nasal or sinus surgery. * Recent vaccinations or intention to receive vaccination before the final follow up visit. * 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 ino…