LIBOI, Kenya - UNICEF says it is trying to vaccinate more than 300,000 children in Kenya in an emergency program designed to prevent an outbreak of disease as refugees stream into northern Kenya from famine-hit Somalia.

Jayne Kariuki from UNICEF said Wednesday that four northern Kenyan regions will be targeted along with Dadaab, the world's largest refugee camp, during the two-week program to immunize the children against polio and measles.

The children will receive vitamin A and de-worming tablets. In Liboi, a dusty town in Kenya near the border with Somalia, mothers in long robes clustered around with children as aid workers dispensed medicine under a thorn tree.