Reporter's Notes: Predicting Swine Flu

The last time we reported on Swine flu, or 2009 H1N1 virus, the Centers for Disease Control and Prevention was considering whether or not to invest in a vaccine for the new influenza strain.

Now, after several delays, the first batches of vaccines — first, a nasal spray version, then an injectible vaccine — is due to hit hospitals and clinics across the country.