In addition to protecting against measles infection, measles vaccine (MV) strengthens the individual's ability to combat infections in general - MV has beneficial non-specific effects (NSE) lowering the risk of death and admissions by around 30%.

In Guinea-Bissau 30% of children do not receive a routine MV scheduled at 9 months of age, putting both the individual child's health and measles eradication at risk. The coverage of a second dose of MV, which was added to the Bissau-Guinean vaccination programme in 2022, is even lower. WHO recommends vaccination at health system contacts, including those for curative services. At the paediatric ward of the national hospital in Guinea-Bissau, there are more than 2600 yearly contacts with measles-un or under-vaccinated children aged 9-59 months, but no vaccines are given. In a randomised controlled trial, we will assess the effect of providing MV vs placebo to 5400 children at hospital contacts (at discharge or after an out-patient consultation) to test the hypothesis that MV reduces the risk of admission or death (composite outcome) by 25% over the subsequent 6 months.

Inclusion Criteria:

• Measles-unvaccinated children
• 9-59 months with a hospital contact (discharged or outpatient consultation) at the paediatric ward at the national hospital Simao Mendes.

Measles-under-vaccinated children (received first but not second dose of MV)

• 15-59 months with a hospital contact (discharged or outpatient consultation) at the paediatric ward at the national hospital Simao Mendes.

Exclusion Criteria:

• Axil temperature >38.0
• Mid upper arm circumference <110 mm

Provided request, data can be made available