A Danish patient has the distinction of being the first known, apparently-documented case of Tamiflu-resistant swine H1N1.
That's a mouthful.
It is being dutifully reported across the globe, and no doubt shares of Roche are tumbling.
I hope none of you bought Roche heavily, right? Because you knew this day would come. I predicted it back in April, on this blogsite. And it was not too Nostradamian, admittedly. You see, in 2006-07, Tamiflu-resistant seasonal H1N1 was around 4% of all samples tested. the following season, 2007-08, it had climbed to 10%. And this past season, seasonal H1N1 was 97% Tamiflu-resistant.
Tamiflu resistance has cropped up from time to time in areas hit by human H5N1 bird flu infections. So it was not a stretch to imagine that Tamiflu resistance would occur.
Nor is it too surprising that Denmark would be the first occurrence. Recall (search "Norway" or "Sweden" on this site) that Scandinavia has a far higher proportion to Tamiflu resistance than other nations. Denmark ain't that far away from Scandinavia, as the migrating bird flies. Here's what I wrote, back in January, 2008:
Normally, you would expect Tamiflu-resistant H1N1 influenza to show up in areas where Tamiflu is prescribed. But that is not the case here! There are no known cases of H1N1 with the H274Y mutation in Japan, where Tamiflu is habitually overprescribed;and 70% of H1N1 is showing Tamiflu resistance in distant Norway, where Tamiflu is rarely, if ever, prescribed. Quite a conundrum.
Dr. (Henry) Niman believes that Tamiflu-resistant H1N1 with the H274Y mutation has already been detected in these US isolates:
ISDN282211 A/Hawaii/21/2007 H1N1
ISDN282224 A/Hawaii/28/2007 H1N1
ISDN282222 A/Hawaii/28/2007 H1N1
CY027037 A/Kansas/UR06-0104/2007 H1N1
ISDN282240 A/Minnesota/23/2007 H1N1
ISDN263890 A/Texas/31/2007 H1N1
Norway's seasonal H1N1 was 70% Tamiflu-resistant in late 2007. That's when ours was 4% resistant. If we are to assume our doctrine/dogma that wild birds and globalization and travel move virus mutations, then at least in this one Danish patient, H1N1 has recombined with its seasonal cousin and has conferred Tamiflu resistance. If it has happened once, it has already happened dozens of times. The simple question is: Will this mutation hold?
I expect so. Tamiflu is a weapon of unknown duration and potency in this fight.Use it or lose it. Here;s the Reuters story (with a tip of the cap to Mike Coston at Avian Flu Diary:)