Influenza comes around every year. So why is this year’s flu season proving much worse than expected, with millions infected and at least 120 people already dead?
The disease is caused by influenza viruses of which four groups exist (types A,B, C and D). The first three infect people, and the first two may cause serious disease. This year, there have been significant numbers of both A and B type infections. The A type has acquired the name Aussie flu because it first started infecting large numbers of people Down Under in June 2017. The current B-type is commonly referred to as Japanese flu, or Yamagata type, based on its initial identification in the 1990s. The reality is that Aussie flu is unlikely to have originated in Australia and Japanese flu has been in circulation around the world for decades.
Different flu viruses are distinguished from each other in several ways. Each virus contains eight strands of ribonucleic acid, their genome, which encode the proteins they need to replicate and spread within their hosts. Two of these proteins, the so-called H and N proteins, sit at the surface of the virus and allow invasion of host cells where they replicate. As they sit at the virus surface they are vulnerable to attack by our immune system.
But if our immune system has never previously seen particular
Source: How the flu season turned deadly – are NHS vaccine failures to blame? : New Statesman