"During the pandemic [Influenza A(H1N1)pdm09] period in 2009-2010, an influenza A (Inf-A) virus with H1N2 subtype (designated as A/Eastern India/N-1289/2009) was detected from a 25 years old male from Mizoram (North-eastern India).
The outcome of this full genome study revealed a unique reassortment event where the N-1289 virus acquired it's HA gene from a 2009 pandemic H1N1 virus with swine origin and the other genes from H3N2-like viruses of human origin.
This study provides information on possibility of occurrence of reassortment events during influenza season when infectivity is high and two different subtypes of Inf Aviruses co-circulate in same geographical location."
This is interesting, and sobering news: it shows how easily this sort of thing can happen; it is perhaps fortunate that both the NA of the new virus came from a circulating type, as otherwise the virus could have spread as far and been as serious as the new H1N1.
I thank Russell Kightley for the reassortant influenza virus graphic.