"Other approaches to accelerating influenza vaccine production involve use of what are referred to as dose-sparing technologies. These are innovations that allow less antigen to be used for each vaccine dose, without compromising immunogenicity or safety. Dose-sparing technologies have the potential to markedly increase vaccine production potential in a pandemic. Adjuvants (compounds that enhance the immune response to a vaccine and therefore reduce the amount of vaccine virus required for each dose) are one such technology. The most commonly used adjuvant today is an aluminum compound found in many childhood vaccines, but which is not used in influenza vaccine. Oil-in-water emulsion adjuvants show the greatest advancement and promise in terms of dose sparing for influenza vaccines. Other potential technologies might involve self-adjuvanting recombinant or molecular vaccines that have built-in antigen-sparing properties. Other promising candidates and technologies may emerge that lead to development of a universal influenza vaccine, which is the ultimate goal for many influenza vaccine programs. Such a vaccine might need to be given only once, rather than every year as with current seasonal vaccines. Such a universal vaccine would ideally provide protection against all, or at least most, of the many strains of influenza capable of making people sick, including future pandemic influenzas. Plant-produced influenza vaccines are in clinical trials and may prove to be a useful alternative to egg- and cell-based vaccines."