Paradigm Shift Intervention Monitoring
twitter
Live feed of underlying pandemic map data here
Commentary
80%
of Influenza A in Texas is Seasonal H1
Recombinomics
Commentary 05:31
October 31, 2010
The above listing is from the week 42 influenza report from Texas. Although the number of sub-typed influenza isolates are limited, 4 of the 5 sub-typed isolates of influenza A (22 were not sub-typed) were seasonal H1N1 (the other isolate was pandemic H1N1). The finding of seasonal H1N1 in 80% of the influenza A was unexpected, since seasonal H1N1 had been largely replaced by pandemic H1N1 last season and seasonal H1N1 is not covered in the current trivalent vaccine.
The resurgence of H3N2 was noted in a CDC alert last August, but there has been little said about seasonal H1N1. In the CDC week 42 report, seasonal H1N1 is not listed in the initial summary page and the graph of isolates by sub-type shows no seasonal H1N1 for weeks 40-42. However, as seen above, Texas is reporting seasonal H1N1 in 4 of 5 influenza isolates, while Pennsylvania is reporting seasonal H1N1 in 1 of 3 H1 isolates (although most sub-typed influenza A in week 42 in PA is H3N2). Canada is also reporting that 1 of 2 H1 samples in week 42 is seasonal H1.
Neither TX nor PA has provided any additional information. Last season the rare seasonal H1N1 was characterized as Brisbane/59/2007 in which Tamiflu resistance (H274Y) has become fixed.
In addition to concerns about widespread H274Y in seasonal H1N1, recent sequences from Argentina have raised concerns about a new pandemic H1 reassortant with seasonal H1 from 2003. Although the two isolates in Argentina were from swine, human H and N combined with six gene segments from pandemic H1N1 raises concerns of a reintroduction into humans, and these newly introduced genes would sub-type as seasonal H1 since the H1 is from 2003 seasonal H1.
More information, including sequence and antigenic characterization of the seasonal H1 in TX, PA, and Canada would be useful.
Concerns over widespread H274Y co-circulating with pandemic H1N1, as well as newly formed reassortants with seasonal H1 from 2003, are quite real.
Media Links
Recombinomics
Presentations
Recombinomics
Publications
Recombinomics
Paper
at Nature Precedings