I have a short piece at the Diplomat on the spread of the Spanish Flu in India, China, and Japan. The three enjoyed very different circumstances, and the impact of the influenza varied considerably across them.
The world of 1918 was far less globalized than the world of today, with lower levels of international trade and international travel. Nevertheless, the influenza spread rapidly, attacking in three distinct waves in countries around the world. Distance provided little protection. The war itself helped spread the disease, as US soldiers brought it to Europe, and Europeans spread it across the rest of the world. The flu made its mark on the great nations of East Asia as well, although with vastly different effects in each.