How to maintain surveillance for novel influenza A H1N1 when there are too many cases to count.

The article presents strategies in maintaining surveillance during an influenza A H1N1 pandemic. It stresses the importance of accurately measuring a set of illness indicators that can be gathered at a population-wide level. Defining a process by which consistent samples from people with severe acute respiratory illness and mild acute respiratory illness or influenza-like illness are tested for pandemic H1N1 virus daily or weekly in sentinel population is advised. The isolation of virus from subsets of mild and severe cases is also suggested.