Acute respiratory infections result in about 1.9 million childhood deaths per year, and 20% of the deaths are in India. Influenza vaccines, although licensed in India, are seldom given. Indeed, it is not known whether influenza vaccine efficacy in a tropical developing country will be the same as in developed countries.

In addition to defining the direct and indirect protective effect of influenza vaccine in a tropical developing country, these studies will develop the capacity for influenza virus study and management in the second largest country in the world.