Hackers are using the flu concerns to spread malware. It is a huge blitz of spam which is really a phishing scam:
“A massive spam campaign that poses as a message from the Centers for Disease Control (CDC) asking people to register for H1N1 vaccinations remains a big problem today, a security researcher said.
The messages lead unwary users to a convincing-looking CDC site where they’re asked to create a profile in order to receive a vaccination for the swine flu, which has made headlines for both its aggressive spread and a lack of vaccine. The site urges users to download a vaccination profile archive, and includes a link to that download.”
link: CDC Warning
There is no vaccination registry. Do not give out your personal information. It is just a clever scam.