Originally Posted by Mamabird
Please carefully read the ECDC assessment of the Danish resistant virus, appended to their daily Swine Flu update:
This has been categorized as a secondary resistant virus due to the use of Tamiflu administered to the patient. It is not a primary virus, ie., one that was acquired from another infected person. This is based on the isolation of the viruses in the cluster of contacts around the Danish woman. None of those sequences revealed the NA mutation causing Tamiflu resistance.
The report is rather vague on who and how many were in the cluster, as well as how hard they looked. If the overseas traveler had a mixture, the Tamiflu may have selected H274Y in the patient who developed symptoms after being on Tamiflu for 5 days, while the other isolates may have been collected prior to treatment, keeping the resistant sequence at a low level.
This is somewhat like the data for S227N in H5N1 in Tuirkey. The index case had S227N, but his sister didn't. Webridge said the S227N developed in the index case but subsequently two more sequences were release from others in Turkey (they would say from who) and one had S227N while the other didn't. In all likelihood all four had S227N and the published sequence represented what grew out in cluture. Of the four sequences two had S227N and two didn't.
The same thing happened in the SARS outbreak. All of the polymorphisms really originated with the index case, but many were absent from the sequence from the index case and many jumped contacts
I will still predict that H274Y will soon start appearing in swine H1N1, including patients who are NOT taking Tamiflu.
Notice that this group STILL can't explain how H274Y in seasonal flu managed to jump from genetic background to genetic background in the absence of Tamiflu and just calls it "complex".