As long as issues regarding the worker safety and the intellectual property rights attached to reverse genetics can be sorted out beforehand, this promising technique could be the key factor for ensuring adequate production of pandemic vaccine. (2) Whether the pandemic threat is due to a re-emergent (A/H2-like) or novel (e.g. A/H5-like) virus will determine not only the kind of vaccine that should be produced but also whether one or two doses will be required.