Over the last decade, American donations to fight malaria in Africa have saved the lives of nearly two million children, according to a new analysis of mortality rates in 32 countries there.

The study, published by PLOS Medicine this month, looked at the long-term effects of the President’s Malaria Initiative, a program started by President George W. Bush in 2005 that has spent over $500 million a year since 2010.

The results debunk one of the persistent myths of foreign aid: that it has no effect because more children survive each year anyway as economies improve.

The researchers — economists from the University of North Carolina and Harvard — looked at death rates for children under 5, contrasting the 19 countries that get American malaria aid (mostly in the form of mosquito nets, house spraying and malaria pills) with 13 countries that do not.