Children's charity Unicef is hoping to give vaccinations to 800,000 children affected by the recent Asia earthquake.
The United Nations backed agency wants to stop children in the region from catching a number of serious diseases.
At least 73,000 people are thought to have been killed in the quake, with the UN estimating that as 17,000 of them were children.
And they're worried that even more children could die unless they get clean water and medicine soon.
The agency hopes its 600 teams will be able to immunise 800,000 kids in less than two weeks, having already helped 300,000.
The vaccines are for diseases like measles, polio, diphtheria and tetanus.
The earthquake on 8 October left tens of thousands of people injured and up to three million people homeless.