MRV-MNP

This is a phase 1/2, single-centre, double-blind, double-dummy, randomized, active-controlled, age de-escalation trial. Age de-escalation will be based on a review of the safety data from the preceding cohort (adults for toddlers and toddlers for infants) up to day 14 post study product administration by a data monitoring committee (DMC). All participants will receive either the MRV-MNP and a placebo (0.9% sodium chloride) SC injection (PLA-SC) or a placebo-MNP (PLA-MNP) and MRV by the SC route (MRV-SC). Only those study staff randomizing participants and preparing the study products for administration will be aware of the products administered. Those administering the study products, all other trial staff and the participants and parents will be blinded to treatment group. 45 adults (18 to 40-years-of-age) will be randomized in a 2:1 ratio. Thus, 30 adults will receive MRV-MNP and PLA-SC while 15 adults will receive MRV-SC and PLA-MNP. 120 toddlers (15 to 18 months-of-age) will be randomized in a 1:1 ratio. Thus, 60 toddlers will receive MRV-MNP and PLA-SC while the same number of toddlers will receive MRV-SC and PLA-MNP. 120 infants (9 to 10 months) will also be randomized in a 1:1 ratio. Thus, 60 infants will receive MRV-MNP and PLA-SC while the same number of infants will receive MRV-SC and PLA-MNP. Solicited local and systemic AE will be collected daily from all participants from the day of study product administration to day 13 post study product administration. Unsolicited AE and SAE will be collected from the day of study product administration to day 180 post study product administration. All participants will have laboratory investigations (hepatitis B, hepatitis C, hematology and biochemistry) conducted as part of screening. Adults will have safety laboratory investigations repeated on day seven and day 14 post study product administration. Toddlers and infants will have safety laboratory investigations repeated on day seven post study product administration. All participants will have measles- and rubella-specific SNA titers and measles- and rubella-specific IgG concentrations measured at baseline and day 42 and 180 post study product administration. Other Expanded Program on Immunization (EPI) vaccines due in toddler (oral poliovirus vaccine, diphtheria-tetanus-pertussis) and in infants (oral poliovirus vaccine, yellow fever vaccine and MenAfriVac® [due at 12 months]) will be given by the investigator team at the day 42 study visit (V4).