Inactivated influenza vaccines: recent progress and implications for the elderly

Area of Science:

• Immunology
• Vaccinology
• Gerontology

Background:

• Annual influenza vaccination is recommended for the elderly, but immune responses are less vigorous in this population.
• Factors contributing to decreased vaccine efficacy in the elderly include reduced immune cell function and thymic output.
• Conventional adjuvants like aluminium-based mineral salts (alum) offer only marginal improvements in influenza vaccine immunogenicity for older adults.

Purpose of the Study:

• To review strategies for improving influenza vaccine immunogenicity and protection in the elderly.
• To discuss the role of adjuvants, high-dose antigens, carrier systems, and alternative immunization routes.

Main Methods:

• Review of recent research focusing on enhancing immune responses to influenza vaccines in aged populations.
• Analysis of adjuvants such as MF59 and AS03, and alternative delivery methods like intradermal vaccination.
• Examination of clinical trial data on the safety, tolerability, and immunogenicity of novel vaccine approaches.

Main Results:

• Adjuvants like MF59 and AS03 have demonstrated increased immunogenicity of influenza vaccines with acceptable safety profiles.
• Intradermal influenza vaccination, facilitated by new injection systems, has shown improved immunogenicity compared to standard vaccination.
• High-dose antigen vaccines and carrier systems (liposomes/virosomes) are also being explored to boost antibody response.

Conclusions:

• Adjuvanted and intradermal influenza vaccines show promise for enhancing immune responses in the elderly.
• Further observational studies are needed to correlate improved immunogenicity with clinical protection against influenza and its complications.
• Continued research into novel vaccine strategies is crucial for better protection of vulnerable aged populations.