Antigenic drift: Meaning (information, definition, explanation, facts)

Antigenic drift refers to mutations in the influenza virus over time. Such mutations occur almost yearly in the influenza virus. For this reason, vaccination is required on a yearly basis. In influenza mutations happen frequently because the virus is highly unstable and has no way of checking it's DNA for errors. Even a tiny error in the DNA is permanent. Antigenic drift has been responsible for large outbreaks in the past, like the outbreak of influenza A Fujian(H3N2) in the 2003 - 2004 flu season. All influenza viruses experience some form of antigenic drift, but it's most pronounced in the influenza A virus. Antigenic drift is not the same as antigenic shift, which is a major change in the surface proteins on the virus.