Immunogenicity and effectiveness of virosomal adjuvanted vaccines against influenza: a brief review of their utility in the elderly population.

The World Health Organisation (WHO) estimates that seasonal influenza affects approximately 5-15% of the population on an annual basis and these outbreaks are responsible for significant morbidity and mortality resulting in increased hospital admissions. Annual vaccination remains the main public health strategy for containing influenza. Inactivated influenza vaccines offer a great deal of protection against influenza but these vaccines are not optimal for older adults due to their waning immunity and other factors affecting immunogenicity. Virosomes, stimulate the immune system in a similar way as a natural infection and studies have shown that the virosomal adjuvanted influenza vaccine is immunogenic and safe in different population groups including: the elderly, children and immunocompromised subjects. Currently available data suggest improved immunogenicity of the virosomal adjuvanted vaccine in the elderly and in subjects without protective antibody as compared to conventional vaccines.