...though, apparently, no longer considered a possibility.
There had been hope that the current seasonal vaccine might do some good, since it contains an H1N1 virus component — meaning the new swine flu strain was at least in the same family of viruses. But the new H1N1 virus is apparently too different for the current vaccine to offer what scientists call "cross protection."
http://www.npr.org/templates/story/story.php?storyId=10... Hardly impossible, as specific as vaccines may be. It was a possibility seriously being considered by people with medical backgrounds at the time.