Swine Flu Is Not Done With Us Yet
News is viral, too. It gets passed around, it inflames the national conversation, and then one day the fever breaks and it's forgotten and life returns to normal. So it is with swine flu. The story is falling off the front pages. Schools are reopening. The CDC says it's no more severe, this strain, than the seasonal flu. We reported in Saturday's paper that the initial estimate of the fatality rate in Mexico was likely mistaken, and on Sunday the CDC boss, Richard Besser, said the same thing.
But none of that means that this was a false alarm. It is quite possible that this flu will wander back onto the front page.
As epidemiologist Michael Osterholm said a couple of days ago: Anyone who says they know how this will turn out is untrustworthy.
Yes, it's true that all influenza viruses evolve due to natural genetic drift. But new viruses in new hosts are under intense pressure from natural selection. You could view this virus as being a bit like a 16-year-old that just got his first car.
Here's the last two paragraphs of my story today:
Although some of the worst fears about the current swine flu outbreak have subsided -- the virus doesn't appear to be as virulent as first thought -- the very nature of influenza makes the future of this strain impossible to predict. It will surely evolve further, [Johns Hopkins virologist Andrew] Pekosz said.
"This is a brand-new virus and a brand-new host," Pekosz said. The process of natural selection will tug the virus in new directions, he said. His scientific prediction -- "That gene constellation is probably going to optimize itself to replicate" -- strongly suggests that human beings haven't heard the last of this new swine flu.
A few notes that didn't make the story:
Pekosz said that pig flus that jump into humans usually become dead-ends, but this one has shown that it can go back into pigs. How come?
"We don't know the answer to that. This is something unique that we haven't seen in swine viruses interacting with humans before."
"There's going to be a lot of selection pressure on this virus to change, and we don't know how it's going to change and how that's going to affect its biological properties...The most recent reassortment event was between two swine influenza virus...Now you've got a situation where you've got 6 genes trying to get use to 2 new genes."
It could actually become less virulent, rather than more. But we don't know. We'll have to wait and see.
This virus doesn't pay a lot of attention to the demands of our news cycle.
By Joel Achenbach | May 7, 2009; 11:01 AM ET
http://voices.washingtonpost.com/achenblog/2009/05/swine_flu_not_done_with_us_yet.html#more