My latest piece for Slate examines the unsettling consequences of the United States’ choice of swine flu vaccines.
The good news about these vaccines is that, to judge by the first vaccine trial results, published last week, they appear to work fast, safely — and at about a half to a quarter of the doses that the CDC expected. This means we effectively have about two to four times as many vaccines as we had figured we would. Since we ordered 195 million doses, we could vaccinate damn near the whole country.

If the fast-tracking efforts continue to work and the flu peaks closer to Christmas than Columbus Day, this robust and effective vaccine supply stands to sharply check swine flu in the United States, saving anywhere from a few thousand to 50,000 lives.

That’s the good news. The bad news?

But what if we could save two to four times that many lives by vaccinating another 200 million to 300 million people worldwide?
Well, we could have—but the United States effectively decided not to do so when it ordered its vaccine supply. Back in May, many other countries ordered swine flu vaccines that include boosters, called adjuvants, that reduce by half or more the amount of antigen (the imposter or inactivated infectious agent) a vaccine requires to be effective. The United States, however, ordered almost all of its doses in the nonadjuvant, or unboosted, form—an older model of vaccine, considered the U.S. standard, that uses more antigen but creates vaccines that are (at least theoretically) safer. That safety, however, comes at the cost of exhausting the precious antigen supplies much faster — and leaving hundreds of millions elsewhere unvaccinated.

Altogether, I conclude,

if the virus retains its present, relatively “mild” course—killing about as many as the seasonal flu but more heavily concentrated on adults under 60, especially the sick and the pregnant—this could mean some 20,000 to 50,000 deaths.

It’s not pretty, and it’s not simple. For the full range of complications (well, as full as I can make it in about 1000 words), check out the whole story.
You’ll also want to check out some of the posts that drew this problem and some of its many wrinkles to my attention. Foremost is a great post from Revere at Effect Measure, who serves as a peerless — and peerlessly passionate and informed — guide to things infectious, especially flu. Close behind is Columbia University virologist Vincent Racaniello, who keeps a blog, and some great links and podcasts, at his Virology Blog.
Cheers.