Mass Vaccine and Drug Administration, Bangladesh

Participants in Arms 1 and 2 will receive three rounds of antimalarial drugs - each round starting on the day of vaccination (Day 0) at Study Months 0, 1, and 2. Each round consists of three daily doses of co-formulated dihydroartemisinin/piperaquine on Day 0, 1, and 2 (i.e. the day of vaccination and each day for 2 days after). The drug dose is based on the weight of the participant at the first visit (M0D0). Dihydroartemisinin/piperaquine tablets (Shanghai Fosun Pharmaceutical Co., Ltd.) for adult participants each contain 40 mg dihydroartemisinin and 320 mg piperaquine with a therapeutic dose range between 2-10 mg/kg/day dihydroartemisinin and 16-26 mg/kg/dose piperaquine. In addition, each participant will receive a single low dose primaquine on the day of vaccination (Day 0; Table 4). One single low dose primaquine of approximately 0.25 mg/kg (Thai Government Pharmaceutical Organisation) will be administered. Children under 10kg do not receive PQ.

The mixing prior to administration strategy will involve withdrawal of 0.5 mL antigen from one vial of R21 Malaria vaccine and adding it to Matrix-M1 vial. 0.5 mL of R21 antigen shall be withdrawn from another vial of R21 Malaria vaccine and be added to the same Matrix-M1 vial. The total volume in Matrix-M1 vial will be 1.5 mL. After addition the content will be mixed gently, and 0.75 mL of the mixture will be withdrawn and administered to participants. Each dose of 0.75mL (after mixing of R21 with Matrix-M1) will contain 10 µg of R21 and 50 µg for participants 14 years and older. In children up to 14 years a 5 μg will be used.