Influenza factsheet

Influenza is an acute viral infection of the respiratory tract. There are three types of influenza virus: A, B and C. Influenza A and influenza B are responsible for most clinical illness. Influenza is highly infectious with a usual incubation period of one to three days.

Public Health England has issued a factsheet about the viral disease. Here is an excerpt:

Changes in the principal surface antigens of influenza A – haemagglutinin and neuraminidase – make these viruses antigenically labile. Minor changes described as antigenic drift occur progressively from season to season. Antigenic shift occurs periodically, resulting in major changes and the emergence of a new subtype with a different haemagglutinin protein. Because immunity from the previous virus may not protect completely against the new subtype, the population may have little or no immunity, and this may therefore lead to widespread epidemics or even a pandemic.”

For further details see PHE.

Posted by Tim Sandle