A Study to Evaluate the Safety and Immunogenicity of ChAdOx1-VZV in Healthy Adults Aged 50-65 Years

This is a randomized, observer blind and controlled study. Participants in low-dose and high-dose IM group will be randomized in a ratio of 2:1 to receive either the investigational product or the control. Participants in the IH group will receive either inhaled investigational product or saline in a ratio of 3:1. Enrollment will be in an ascending order of dosage groups. All participants will receive 2 doses in 4 months interval. Blood samples will be collected for immunogenicity evaluation over the time course of the study.