How do different types of flu get named and what do those names mean?
Flu, also called influenza, is a viral infection of the nose, throat and lungs, which are part of the respiratory system. The viruses that cause influenza are divided into four categories named with letters. Influenza A is the most common type. The others are influenza B, influenza C and influenza D.
Influenza A viruses are further divided into subtypes. These subtypes are grouped based on two proteins on the surface of the viruses. One protein is called hemagglutinin (H), and the other is neuraminidase (N). There are many H and N subtypes, and each one is numbered. H1N1 flu is a subtype of influenza A.
Influenza subtypes include many different H and N combinations. Only a few of these subtypes infect people. The influenza A subtypes currently spreading in people are H1N1 and H3N2. Most seasonal flu vaccines target those subtypes and an influenza B virus.
History of infectious disease outbreaks and vaccines timeline.
Learn about the history of major disease outbreaks, epidemics and pandemics, as well as the impact vaccines and research had on many infectious diseases.
Find out more at History of infectious disease outbreaks and vaccines timeline.
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