Vaccines for preventing influenza in the elderly

Area of Science:

• Gerontology
• Immunology
• Public Health

Background:

• Influenza poses significant risks to the elderly, including complications, hospitalization, and death.
• Influenza vaccination aims to mitigate these risks in vulnerable older populations.
• This review updates previous findings on influenza vaccines in the elderly.

Purpose of the Study:

• To evaluate the efficacy, effectiveness, and safety of influenza vaccines in individuals aged 65 and older.
• To assess the impact of influenza vaccination on reducing influenza incidence and related outcomes in the elderly.

Main Methods:

• Systematic review of randomized controlled trials (RCTs) and quasi-RCTs.
• Searches conducted across multiple databases including CENTRAL, MEDLINE, Embase, Web of Science, CINAHL, LILACS, ICTRP, and ClinicalTrials.gov.
• Data extraction and risk of bias assessment performed independently by review authors, with GRADE certainty ratings for key outcomes.

Main Results:

• Influenza vaccination may reduce influenza risk (low-certainty evidence) and influenza-like illness (ILI) risk (moderate-certainty evidence) in older adults.
• Vaccination necessitates vaccinating 30 individuals to prevent one case of influenza and 42 to prevent one ILI case.
• Limited data and underpowered studies prevent definitive conclusions on mortality, pneumonia, and hospitalizations; harms like fever and nausea require further investigation.

Conclusions:

• Influenza vaccines may offer a reduced risk of influenza and ILI in the elderly, but evidence is limited by study biases and diagnostic method uncertainties.
• Current evidence on vaccine effectiveness against complications like pneumonia and mortality is of poor quality and insufficient for public health guidance.
• Further research and investment in a new generation of influenza vaccines specifically for the elderly population are recommended.