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Friday, October 24, 2008

Tamiflu Resistance Confirmed

While you are pondering whether or not to take the flu jab you might wish to read about vaccine resistance, something you don't see or hear usually in mainstream media.
First Confirmed H1N1 in CanadaTamiflu ResistantRecombinomics, October 23, 2008

Since 1 September 2008, National Microbiology Laboratory (NML) has antigenically characterized three influenza viruses: one influenza A/Brisbane/59/2007(H1N1)-like and two influenza B/Florida/4/2006 viruses, which are the influenza A(H1N1) and influenza B components recommended for the 2008-09 influenza vaccine.

The testing results showed that the influenza A(H1N1) isolate was sensitive to amantadine, however, it was resistant to oseltamivir due to the H274Y mutation.

The above data from the most recent (week 41) report on seasonal flu in Canada indicates that the first confirmed influenza A case this season was H1N1 and was Tamiflu (oseltamivir) resistant. Data had been trickling in for influenza in the northern hemisphere this flu season. Several countries, including the US and Canada had high frequencies of H274Y in H1N1 isolates, but the above report is on the first Canadian isolate in the 2008/2009 season.

In the southern hemisphere, several countries (South Africa, New Zealand, New Caledonia) reported frequencies of 100%, raising concerns that H274Y was becoming fixed in human H1N1. The high levels in last season in the northern hemisphere was limited to clade 2B (Brisbane/59), as found in the isolate in Canada. H274Y was present in patients who had not recently taken Tamiflu, indicating the sub-clade with H274Y did not have a fitness penalty, and the increase to 100% levels indicated that the sub-clade had a selection advantage.

The early data from Canada supports concerns that the H274Y levels in H1N1 in the northern hemisphere will be close to 100% this season.

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