Earlier Prime-BOOST Schedule to Improve MEasles Protection in High Burden Settings

1. Trial Participants Children aged 6 months (23 - 28 weeks) at time of screening 2. Inclusion Criteria * Aged 6 months (23 - 28 weeks) at time of screening * Received all previous vaccines as per country Expanded Programme of Immunization (EPI) schedule, verified by child health card * Parents/caretakers willing to give informed consent for their and their children's participation and stay in the geographical area where the study would be conducted 3. Exclusion Criteria The participant may not enter the trial if any of the following apply: * Child not healthy enough to be vaccinated in the opinion of the investigator * Recent family history of measles infection (since birth) * Previous receipt of any measles vaccination * A family history of congenital or hereditary immunodeficiency other than HIV * Receipt of more than 1 week of immunosuppressant or immune modifying drugs e.g. high dose steroids. * Major congenital defects or serious chronic illness that in the opinion of the investigator are likely to modify immune responses or the ability to comply with the requirements of the study. * History of any neurological disorders or seizures * Administration of immunoglobulins and/or any blood products since birth or planned administration during the study period * Other abnormalities or medical history that contraindicated measles vaccination