Is the slogan properly written in English?

Do you think the slogan is properly written?
Slogan: "Prevent Spreading from Inside, Block Breaking-in from Outside"
By which it refers to ""Prevent H1N1 Spreading from Inside the colleg campus, Block H1N1 Breaking-in from Outside compus"

Context;
There are posters in the dormitories to remind students to do their share of infection-preventing work. The college administrations in the province have enhanced the epidemic work against HINI based on the principle of "Prevent Spreading from Inside, Block Breaking-in from Outside".