The numbers now affected are huge, OHCA says: 3.2m in Ethiopia, 3.2m in Kenya, 2.6m in Somalia and more than 100,000 in Djibouti.
Every month during 2011, about 15,000 Somalis have fled their country, arriving in Kenya and Ethiopia, according to OCHA.
While conflict has been a fact of life for them for years, it is the drought that has brought them to breaking point.
Many have walked for days, are exhausted, in poor health, desperate for food and water.
Nearly one third of all children in the Juba region of Somalia are acutely malnourished, while in parts of Ethiopia the figure is even higher, the UN research says.
The price of grain in affected areas in Kenya is 30-80% above average.
The spokeswoman for OCHA, Elizabeth Byrs, said appeals for Somalia and Kenya, each about $525m (£328m), are barely 50% funded, while a $30m appeal for Djibouti has raised just 30% of the needed funds.
(source)