At the moment, the Influenza vaccines are produced in chicken eggs. This can cause problems In rare cases in people that are allergic to chicken protein. The biggest problem, however, lies in the time it takes to produce: it takes six months before sufficient vaccine is available, which is far too long if a novel Influenza variant suddenly emerges.
Medicago, a Canadian company, has developed a technology wherein genetic Influenza-material (virus-like particles or VLP) is implanted into tobacco leaves. Because tobacco leaves grow quickly, more virus-like particles are produced. The production process is six times faster than the older process in chicken eggs. Plus it's a lot cheaper.
At this moment in time you are probably wondering why this vaccine isn't available yet. The hurdle is that every medicine needs to undergo various test phases to study if it doesn't pose any danger to humans and if it does what it is proposed to do. It has now been entered into the so-called Phase III and thus the end is in sight, because there is only Phase IV to sustain before the vaccine is ready to go to the market.
 D'Aoust et al: The production of hemagglutinin-based virus-like particles in plants: a rapid, efficient and safe response to pandemic influenza in Plant Biotechnology Journal – 2010