In a first for any infectious disease, a vaccine against flu has been made out of messenger RNA (mRNA) – the genetic material that controls the production of proteins. Unlike its predecessors, the new vaccine may work for life, and it may be possible to manufacture it quickly enough to stop a pandemic.
http://www.newscientist.com/article/dn22529-new-vaccine-may-give-lifelong-protection-from-flu.html