Adjuvants for influenza vaccine

• Published in: Research in immunology (Paris) 1998, Vol.149 (1), p.19-23
• Main Authors: Le Cam (xc), N.N. Bouveret, Ronco, J., Francon, A., Blondeau, C., Fanget, B.
• Format: Article
• Language: English
• ISSN: 0923-2494
• DOI: 10.1016/S0923-2494(98)80037-0

Every year, the influenza virus infects a large part of the world's population. While far greater during pandemic years, at least 3,000 deaths are caused each year by influenza and its complications. Elderly subjects and subjects with an underlying pathology, such as cardiac disease, respiratory disease, renal insufficiency, etc., are those most at risk. Several types of vaccines have been developed which contain either purified inactivated whole virus, split or subunit virions, or which are live attenuated strains. For more than 20 years, such a purified formaldehyde-inactivated Triton X-100 split vaccine has been produced by Pasteur Merieux Connaught. As long as the circulating virus resembles that in the vaccine, efficacy is in the range of 70 to 90% in the adult population. However, in elderly subjects, a lower immunological response is often observed after injection of influenza vaccine, which may be related to ageing. While the elderly generally retain immunity against many previously encountered pathogens, evidence suggests that immunological memory may be impaired as one ages. Furthermore, age-associated alterations in immune function may be linked to changes in the composition of the CD4 compartment, and as a consequence thereof, in the balance of cytokines produced by T cells. These changes affect the cytokine profile of IFN gamma and IL4 production, and therefore, the cooperation of T cells and B cells, which in turn influences the levels and isotype distribution of immunoglobulins. An improvement in the efficacy of the influenza vaccine is thus greatly needed, since the elderly population has both the highest risk of influenza complications and a poor response to vaccination. In order to overcome these problems, vaccine research is progressing in two directions: development of live-attenuated strains and improvement of the current vaccines by addition of adjuvants.