Adjuvant play multiple roles in the improvement of the vaccine adjuvant role.
Scientist initially used adjuvant for the primary purpose of improving the immune response
towards the weak antigen however, the modern adjuvants are been sleeked for multiple roles like:
2.2.1 Dose sparing and antibody responses broadening.
The recent influenza pandemic sleeked the need to produce approximately 1 billion doses of the vaccine, which remained insufficient for the population worldwide. Hence, it was recommended to expand the vaccine technologies beyond egg-based production to include recombinant vaccines. The recombinant vaccine would possess significant advantages over the current vaccine but its poor immunogenicity would require an addition of an adjuvant. The improvement of the immunogenicity would reduce the dose required for the activation of the immune response.22-24
The other reason for influenza pandemics even after immunisation is the emergence of the new virus strain. These strains have different genetic material thus there is no pre-existing memory immunity for these new strains causing widespread disease. Thus to prevent such type of pandemics means new influenza subtype vaccines need to be created vaccines and administered frequently. The viral vaccines take longer time to be isolated (4-6 weeks) whereas the pandemics spread faster as compared to (90 days).25 Therefore the pandemic candidate virus vaccines are developed for probable mutation of the virus e.g. H5N1 produced for H1N1. In various approaches to develop new mock vaccines, new inactivated vaccines have been developed however, they have less immunogenicity. For e.g. the first H5N1 unadjuvanted vaccine developed from Sanofi Pasteur required a higher dose of vaccine antigen (90 µg) however after the introduction of the Aluminium adjuvants in the formulations the dose was significantly reduced to 6-15 µg. Suggesting that the adjuvant addition helped in dose sparing.26