Comment: The background for tamiflu resistance is about 0.3-0.5% of tested cases. When it breaches the 1% of cases tested is roughly when resistance starts to take off. The 4/61 = 6.6% suggests that we are well past this figure.
The question remains, is there some bias in sampling? i.e. were mainly patients that did not get well (i.e. they had flu that was resistant to tamiflu) get selectively tested? This we do not know, But based on the history of seasonal flu resistance, the uptick in resistance cases and the higher percentages, if it continues, is evidence of a breakout.
WHO seems to be downplaying the risk.
Hope everyone had a great Christmas and New Year. Woke to snow this morning.
Tamiflu Resistance Continues to Expand in the United States Recombinomics Commentary 23:10 December 31, 2009
A total of 50 cases of oseltamivir resistant 2009 influenza A (H1N1) viruses have been identified in the United States since April 2009, including four newly identified cases since last week. In specimens collected since September 1, 2009, 40 cases have been identified in the United States.
The above comments from the latest (week 51) influenza update by the CDC indicates that the detection rate of H274Y in the United States remains high. Only 61 new cases were tested in the past week, yet four had H274Y. The rate has exploded in the past 6 weeks in the US and across the northern hemisphere, raising concerns that H274Y will pair up with receptor binding domain changes at position 225, leading to widespread resistance as was seen in H1N1 seasonal flu.
Pandemic H1N1 rates continue to decline in the US, setting the stage for a new variant in the next several weeks as temperatures drop across the northern hemisphere. Once again there were no cases of seasonal H1N1 or H3N2 detected, and influenza B detection also fell to zero, increasing concerns that the pandemic H1N1 will crowd out influenza A, as well as influenza B, paving the way for the emergence of multiple variants of pandemic H1N1, which is far more dangerous than seasonal flu.
The steady rise in H274Y, coupled with increases in D225G/N increase those concerns.
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