Sierra Leone is planning to immunize 1.5 million children over the next four days, in the West African nation's first public immunization campaign, the World Health Organization (WHO) said Friday.

The campaign will take place despite major challenges of delivering basic health services due to an Ebola epidemic that infected more than 12,000 people in Sierra Leone, of which almost 4,000 were killed.

Almost 11,000 health workers will assess children between six months and five years for malnutrition and immunize children up to two years of age against tuberculosis, measles and polio.

The health teams will also administer Vitamin A and deworming tablets, and offer HIV testing for pregnant women and their partners.

Sierra Leone has one of the highest rates of infant and maternal mortality in the world, according to the WHO. About 1,165 out of 100,000 women die during live births, while 156 out of 1,000 children die under the age of five.