This paper has two objectives: to characterize the exposure of developing countries to the international income, prices and monetary shocks and to calculate the social well-being in the period of contagion. Firstly, we develop a theoretical model with a world composed of two countries (developed and developing countries) and measure the level of the exposure of income in developing country to the external shocks trough external trade, international tourism, migrant transfers, external debt, foreign aid, FDI and other private financial flow channels. And, we characterize imported inflation in studying the effect of the international shocks on real exchange rate. Secondly, we search the social well-being. The results suggest that economic disequilibrium in developing country is socially optimal and that the dependence of its income to the domestic industry is necessary to reduce contagion. This conclusion is important for African countries because they import finished products for the households’ consumption. In these conditions, they are exposed to the imported inflation. The domestic monetary and tax policies are not adapted to fight against inflation. Also, they produce and export raw materials essentially toward industrialized economies. Thus, they must develop the domestic industry in order to influence the demand (or prices) of raw materials and to substitute imports by domestic goods in period of hyper-inflation in advanced economies in order to reduce imported inflation.