The deadliness of an influenza virus mainly depends on its ability to efficiently suppress the innate immune system, thereby allowing high levels of virus replication. This is more likely to occur with pandemic influenza where the individual has not been exposed to the new virus subtype before and must rely on the innate immune response to decrease viral replication. If indeed large quantities of virus are produced, high levels of cytokines are produced in the inflammatory, antiviral response. Desquamation of the respiratory epithelium combined with inflammatory processes lead to transudation of large amounts of fluid into the lungs. Progressive hypoxia and acute respiratory distress syndrome may cause death within the first one or two days of the onset of illness.