If anyone is interested in actually seeing data, I have put a (large!) table up here showing flu strains that are most similar to each of the segments of the present H1N1 strain. Also see my earlier posts “Has the new H1N1 been hiding for 11 years? (No.)” and “How fast can influenza change?” for more commentary.

Please note – I am perfectly open to the concept that this virus is most closely related to a 1998 strain and that it’s been hiding — but I need to see actual evidence that fits with biology and observation, not mere repeated assertions and incoherent numerology that’s apparently pulled out of thin air.

while swineflu sequences from the last years from Minnesota,Ohio,Illinois,Iowa are closer to each
other, the new strain is closest to
A/Wisconsin/10/1998

The Mexican H1N1 shows about 96% identity to its nearest neighbours. If you look at recent US swine flu strains you’ll find they’re often about 97% identical to their nearest neighbours, e.g. A/swine/OH/511445/2007(H1N1), especially if you don’t look at multiple isolates from the same outbreak. What’s more, the guys with the most matches tend to be the older strains for obvious reasons — there you look at their progeny as well as their parents. In other words, the sort of variation we’re seeing for the MExican strain is pretty much exactly what we’d expect to see in a random US outbreak — such as happen every year or two. Or are you arguing that A/swine/OH/511445/2007(H1N1) was hiding out in Mexico? Or is it simply that this sort of variance is fairly normal for swine influenzas?

You could just demand to hold life imported swine separately from domestic ones
until they are tested and authorities give an OK.

As for laws, what on Earth do you think you could do? Might as well pass a law making it illegal for wood to float. This isn’t manmade recombination, it’s natural.

On the other hand, this is clearly a wakeup call for more surveillance — swine influenza surveillance has been very scattered and desultory. But you have to remember — influenza, and swine influenza, are universal. Viruses that look like the parent strains of this virus would be everywhere, and would look perfectly ordinary on surveillance. For that matter, this H1N1 would itself look perfectly ordinary on surveillance. You’d have to ban all pig import and export (and much more than that) and it still likely wouldn’t work because some other species’ flu would hop over into pigs and cause an epidemic (remember that the H1N1 swine flus are human-derived!).

The biggest and scariest change in swine influenza that would have been flagged in surveillance was the rise of the triple recombinant in the 1990s — and that turned out to be essentially harmless to humans (unless there turns out to be a 15-year lag in the harm).

We don’t know enough about influenza in general, or swine influenza in particular. Finger-pointing, jumping to conclusions, and prejudice isn’t going to give us any answers.