Emulsion-based adjuvants for improved influenza vaccines

Abstract

Emulsions have a long history of use as potent and effective adjuvants in humans for a range of vaccines, particularly for influenza. Although older mineral oil- and water-in-oil-based emulsion adjuvants did not have an overall safety and tolerability profile to allow them to be acceptable for widespread use, a newer generation of oil-in-water adjuvants has been recently developed, based on the use of the biodegradable oil squalene. These adjuvants have shown particular value in the development of new generation vaccines to offer enhanced protection against both seasonal and pandemic strains of influenza virus. The first oil-in-water emulsion adjuvant included in an approved flu vaccine was MF59, which was originally licensed in Europe in 1997 as an improved influenza vaccine for the elderly. In the very recent past, MF59 and related adjuvants have shown their value by offering the possibility of significant antigen dose reductions and higher potency products in the face of the H1N1 pandemic emergency and other pandemic threats. The recent H1N1 global problem allowed the opportunity for widespread use of emulsionbased adjuvants in a range of population groups in a number of countries, in which strict monitoring of safety was the norm. Importantly, this widespread use allowed the safety profile of squalene-based emulsion adjuvants to be further substantiated in large and diverse populations of humans, including young children and pregnant women. It is our confident prediction that the coming years will see wider use and further licensures for oil-in-water emulsion adjuvants, particularly for improved flu vaccines. © Springer Basel AG 2011.