This trial consists of 4 intervention arms according to the vaccination product: 1) ChAdOx1 Chik, 2) ChAdOx1 Zika, 3) ChAdOx1 Chik and ChAdOx1 Zika as contralateral co-administration, and 4) placebo. There will be a total of 120 participants divided in ten study groups with 12 participants per group (Table 5.1). Groups 1 to 3 will receive ChAdOx1 Chik + placebo administered contralaterally, Groups 4 to 6 will receive ChAdOx1 Zika + placebo administered contralaterally, and Groups 7 to 9 will receive both ChAdOx1 Chik and ChAdOx1 Zika administered contralaterally. Group 10 will receive placebo in both arms.~Enrolment into this study will be implemented in a step-wise dose escalation manner. Participants will be first recruited into the vaccination groups at the lowest dose (Groups 1, 4 and 7). It is only after completion of these low dose groups and upon satisfactory interim clinical safety reviews that participants will be enrolled into the mid dose groups (Groups 2, 5 and 8). Participants in the high dose groups (Groups 3, 6 and 9) will be enrolled last, after completion and interim clinical safety reviews from the mid dose groups. Participants allocated to the Placebo group (Group 10) will be evenly distributed across the dose escalation model.~Randomisation procedures will be implemented accordingly, at a ratio of 3:3:3:1 for each of the four intervention arms.~The study involves a total of 9 visits (screening inclusive) and follow up will be undertaken for 6 months after vaccination day~Innovate UK (project number 971557)
Phase Ib, single centre, double-blind, double-dummy placebo-controlled, randomised, stepwise dose escalated, vaccine trial to assess the safety and immunogenicity of the candidate ChAdOx1 Chik and ChAdOx1 Zika vaccines, given as a standalone vaccines or in co-administration. Healthy volunteers aged 18-50 years old, residents of the metropolitan area of Monterrey (Mexico), will be recruited as participants