Study duration per participant will be approximately: 7 months for Stage 1 participants, 12 to 18.5 months for Stage 2 participants, 12 months for Stage 3 participants and 18 months for Stage 4 participants

In each vaccine group at each age group (Stage 1, 3 and 4 only), the first 5 participants enrolled (sentinels) will be assessed via early safety data review (ESDR) as a cohort for the evaluation of biological safety and overall safety profile for D01-D08 post dose 1. The safety data collected will be reviewed before proceeding with recruitment of remaining participants in each study group. Enrollment of remaining participants randomized to each group will be based on the outcome of the safety assessments of the sentinels: only a positive review outcome will allow the enrollment of the sentinel cohort of the respective lower age group.