Background: All observational studies and a few randomised controlled trials (RCT) suggest that early measles vaccine (MV), in particular an early two-dose strategy, has a much better effect on overall mortality than later MV. These results suggest that MV has a non-measles related beneficial effect on child survival.

Objective: To evaluate in a two-site RCT the effect on child survival and other health indicators of a two-dose measles vaccination schedule by providing an additional dose of Edmonston-Zagreb (EZ) MV as soon as possible after 4 months of age as well as the standard measles vaccine at 9 months of age. The trials are planned in Guinea-Bissau and Burkina Faso. The investigators will test a 40-43% reduction of mortality at each site separately and a 32% reduction overall. Based on the results from the RCT, the investigators will assess the cost-effectiveness of the intervention.

Design, Guinea-Bissau: Newborns are followed through the Health and Demographic Surveillance System (HDSS) of the Bandim Health Project. Information on routine and campaign vaccinations will be collected regularly through home visits and health centre registers. Four weeks after having received the third dose of pentavalent vaccine (Penta3), the children will be eligible for enrollment in the trial if they are not severely ill. Eligible children will be invited to take part in the trial. Provided parental informed consent is given, the children will be randomised to MV at 4 and 9 months of age or only at 9 months. Cost estimates will be based on consumption of services and average cost per unit. The incremental cost effectiveness ratio will be calculated.

Sample size, follow-up and analyses: To detect a 40% reduction in overall mortality at each site the investigators intend to enroll at least 3,750 children in Guinea-Bissau. The children will be followed for survival and hospitalisations to 3 years of age or to the end of the study after three years. The investigators will analyse the effects by site and combined; by sex and season; possible interactions with other interventions like campaigns with drugs, vaccines or micronutrients will be explored.

Antibody study: 450 children will be enrolled in a subgroup study to examine the effect of maternal antibody levels on subsequent antibody responses to MV. The children will be followed to 24 months of age and samples collected at 4, 9 and 24 months of age.

Inclusion Criteria:

Children who

• received the third dose of pentavalent vaccine at least 28 days before enrolment
• are between 4 and 6 months old
• belong to households of the existing HDSS

Exclusion Criteria:

Children

• with serious malformation
• who are severely sick (needing hospitalisation)
• with high fever (>38.5 C axillary temperature)
• who are severely malnourished (mid-upper-arm-circumference (MUAC) < 110 mm and/or bilateral peripheral oedema)
• who have received neonatal vitamin A supplementation
• whose parents/guardians state that they intend to permanently move out of the study area before the child reaches 9 months of age