H1N1 Tamiflu Resistance in UK Increases to 95%
Recombinomics Commentary 18:20
December 3, 2008
Of these 17, 14 are from South West England, one is from Wales, one from Central England and one from North England.
Two oseltamivir-resistant influenza A (H1) specimens have been reported from Scotland.
The above comments from the weekly update from the UK indicate the three most recent H1N1 isolates tested also had had H274Y. Thus, this season 19/20 H1N1 isolates in the UK have H274Y, which matches the level in the United States (20/21 H1N1 isolates have H274Y).
The additional positives confirm that H274Y in H1N1 is widespread in the UK and has been so for a few months. Indeed all of the 8 most recent tests were positive. Similarly, all 19 or the most recent samples in the US were also oseltamivir resistant.
This level is a greater concern in the US, because most of the sub-typed influenza A in the United States in H1N1, including all sub-typed isolates in the latest report. The CDC has requested additional samples from more representative locations, but the numbers from the UK, as well as 1/1 from Norway and 1/1 from Canada indicate most or all H1N1 in Europe and North America will have H274Y (especially if the isolates are clade 2B).
Testing in Canada has been limited (the one reported sample was reported over a month ago), and amantadine resistance testing of H1N1 in the US has also been limited (last year all clade 2C was amantadine resistant), so the frequency of H274Y in clade 2C this season is not clear (no H274Y was in public H1N1 sequences from the US last season).
Although the relative low level of H1N1 in the UK and Europe this season may limit changes in recommendations for Tamiflu usage, the high level in the United States (and possibly Canada), may dictate a change in recommended usage of Tamiflu in North America.
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