Via The Los Angeles Times, an excellent article by plague historian Wendy Orent: What H1N1 taught us. Excerpt (but read the whole thing):
We have learned a lot from the 2009 H1N1 swine flu pandemic.
We have learned, for example, that one basic assumption about pandemics was wrong: You don’t need a radical mutation in a flu virus to produce a pandemic. All you need is enough change within a surface protein for a new strain to blow past acquired immunity and blaze around the world, as this one did.
And we’ve seen that not every pandemic strain is especially lethal. The Centers for Disease Control and Prevention in Atlanta estimated that 11,690 Americans had died of swine flu by mid-January. In a “normal” flu season, the CDC estimates that 36,000 Americans die.
As Peter Palese, an eminent flu virologist from Mount Sinai Hospital in New York, put it, “We were lucky — this was a mellow virus.” It lacks the virulence factors that make highly pathogenic bird flu, or the 1918 pandemic flu virus, so deadly.
In the beginning, the pandemic seemed to have an ominous affinity for the young. But this turned out to be mostly a matter of resistance. Many people born before 1957 have some cross-immunity to the virus because of their exposure to a previous H1 outbreak.
So older people — the usual victims of seasonal flu — caught the new virus at much lower rates. And even among young people, though the attack rate was ferocious and many millions were infected, only a tiny percentage of those who got the flu died.
