Every year, influenza virus causes significant illness globally. Many people are admitted to the John Radcliffe hospital with the virus and tested using molecular test. Currently, we do not use all the information that the test provides. This study aims to use the extra information from the current test (called the CT value) to work out this value can guide how we manage patients with influenza. The study will include various types of the influenza virus to determine whether there are differences in CT value between different types.