Aboriginal children in the Top End have very high rates of hospitalisation for respiratory infection. How much do viruses like influenza contribute to this high burden of disease? What is the impact of viral infection on the invasiveness of bacteria they carry? Do viruses and bacteria work together to cause severe disease? Is there a role for using influenza and future viral vaccines to reduce the rates of bacterial infection?

The primary outcome of this prospective cohort study will be the population-based incidence of hospitalisation attributable to influenza , RSV and other respiratory viruses, among Indigenous and Non-Indigenous infants. This study will also determine the rate of bacterial colonisation among this cohort, comparing children admitted for respiratory infection with children admitted for other reasons. It will determine the rate of coinfection of viruses and bacteria and examine whether coinfection results in more severe disease. This study paves the way for subsequent vaccine trials.

We have recruited over 600 children so far. Laboratory work is underway. The study is due for completion late 2010.