Blogger Jason Kottke has complied a succint, interesting description of the manufacturing process for the H1N1 influenza vaccine:
The most striking feature of the H1N1 flu vaccine manufacturing process is the 1,200,000,000 chicken eggs required to make the 3 billion doses of vaccine that may be required worldwide. There are entire chicken farms in the US and around the world dedicated to producing eggs for the purpose of incubating influenza viruses for use in vaccines.
The rest of the entry is similarly worth reading.