Vaccines for preventing influenza in the elderly

Area of Science:

• Gerontology
• Immunology
• Public Health

Background:

• Influenza vaccination is recommended globally for elderly individuals to prevent severe complications.
• The elderly population and those at high risk are primary targets for vaccination campaigns.

Purpose of the Study:

• To systematically review the evidence on the efficacy, effectiveness, and safety of influenza vaccines in individuals aged 65 years and older.
• To assess influenza vaccine performance across different settings and populations.

Main Methods:

• Conducted a comprehensive search of multiple databases including Cochrane Library, MEDLINE, EMBASE, Biological Abstracts, and Science Citation Index.
• Included randomized, quasi-randomized, cohort, and case-control studies evaluating influenza vaccines compared to placebo or no intervention.
• Stratified analyses by study setting (community vs. long-term care), vaccine match, viral circulation, and co-administration with pneumococcal vaccine.

Main Results:

• In long-term care facilities, well-matched influenza vaccines demonstrated significant effectiveness against pneumonia (46%), hospital admissions (45%), and deaths (42%) during high viral circulation.
• In community settings, vaccines showed modest effectiveness, preventing hospital admissions for influenza/pneumonia (26%) and all-cause mortality (42%), with adjusted effectiveness for mortality at 47%.
• The safety profile of influenza vaccines was found to be acceptable for public health.

Conclusions:

• Influenza vaccination in long-term care facilities partially fulfills vaccination campaign aims by effectively reducing complications.
• The overall usefulness of influenza vaccines in the community setting is considered modest.
• Observed high effectiveness in preventing all-cause mortality in community settings may be influenced by baseline health status and systematic differences between study groups.