B1) to examine whether a two-dose strategy for measles immunization at 6 and 9 months of age can reduce measles incidence by 50% through better coverage or improved seroconversion, and B2) to examine whether a two-dose strategy for measles immunization at 6 and 9 months of age can reduce childhood mortality by 20% through better coverage, better protection against measles or non targeted beneficial effects, and B3) to determine the magnitude and duration of non-measles related changes in morbidity patterns after standard titre measles immunization, in particular to test whether measles immunization is associated with a 15% reduction in the risk of diarrhoea, and B4) to determine non-measles related immunological changes among recipients of measles vaccine in order to establish possible pathways for the non targeted effects of standard titre measles immunization.