In my previous post about the H1N1 Swine flu vaccinations I was wondering what gives with the approval dates. I decided to do a little research.
So here is a bit of influenza history.
The Influenza A subtype H1N1 caused the pandemic of 1918-1919. This subtype continued to circulate but was never again as virulent as in the Pandemic. In 1957 when the Asian Flu H2N2 appeared H1N1 disappeared. In 1968 when the Hong Kong Flu Virus H3N2 appeared the Asian Flu virus H2N2 disappeared. H1N1 re-surfaced in 1977 and has since co-circulated with the H3N2 virus. Both strains were in the 1998 and later vaccines.
So these past vaccines for H1N1 are for past strains that were circulating. The Vaccines now being approved are for the current variations going around and identified in 2007.
It appears the biggest part of the confusion is when the Swine Flu was renamed to H1N1 it sounded like H1N1 was an entirely brand new subtype like the Asian or Hong Kong flu were when in reality H1N1 has been around since the 1918 Pandemic though not as severe. The CDC and the Media seems to have left this part out.
