“Severe drought, famine, war, large-scale population movements, and overcrowded refugee camps, led to a complex emergency in the Horn of Africa during 2010–2011. In Somalia, low measles containing vaccine (MCV) coverage in areas, where immunization services could not be provided for nearly 2-years, led to a massive measles outbreak, primarily among children aged less than 5-years of age. Population movements, including large influxes of refugees from southern and central areas of Somalia into camps in Kenya and Ethiopia, near the Somalia borders, led to measles virus transmission among refugees, and to outbreaks in Ethiopia and Kenya. After outbreak response immunizations (ORIs), the number of cases decreased in the refugee camps.”