2.2. Vaccines

The investigational product (IP) consisted of oral RV3-BB vaccine or placebo. RV3-BB clinical trial lots were prepared at Meridian Life Sciences (Memphis, USA) to a titre of 8.3–8.7 × 10⁶ FFU/mL in serum free media supplemented with 10% w/v sucrose. Participants received four 1 ml oral doses of IP (vaccine or placebo) according to their treatment allocation, with doses administered at 0–5 days (IP dose 1), 8–10 weeks (IP dose 2), 14–16 weeks (IP dose 3) and 18–20 weeks of age (IP dose 4) (Fig. 1). In the neonatal vaccine group IP doses 1, 2, and 3 were RV3-BB and dose 4 was placebo, and in the infant vaccine group, IP dose 1 was placebo and doses 2, 3, and 4 were RV3-BB. In the placebo group all four IP doses consisted of media with 10% w/v sucrose and was visually indistinguishable from the vaccine. IP doses 2, 3 and 4 (vaccine or placebo) were preceded by a 2 ml dose of antacid solution (Mylanta® Original). Feeding was withheld for 30 min before and after each dose.

Study Design with blood collection time-points for Sub-study A and Sub-study B.