5 n-count A medium is a substance or material which is used for a particular purpose or in order to produce a particular effect. Blood is the medium in which oxygen is carried to all parts of the body..., Hyatt has found a way of creating these qualities using the more permanent medium of oil paint.
An influenza pandemic is a global outbreak of disease that occurs when a new influenza A virus appears or âemergesâ in the human population, causes serious illness in people, and then spreads easily from person to person worldwide. Pandemics are different from seasonal outbreaks or âepidemicsâ of influenza.
It is well known that simultaneous infection of a single cell by two distinct influenza A viruses can lead to gene mixing, or reassortment, which can result in the generation of a novel influenza virus strain, and it is believed that most human pandemic viruses arose in this manner.