Efficacy of influenza vaccine in adults. Systematic review

This study addresses the challenges and advances in the vaccination of older adults in a context of global population aging, evaluating its effectiveness in the prevention of serious infectious diseases. Immunosenescence and comorbidities in this population may affect the response to vaccines, decreasing their efficacy. Through a systematic review, we analyzed recent studies evaluating various vaccine formulations and strategies such as high doses, natural adjuvants (e.g., probiotics and nondigestible polysaccharides), and vaccine coadministration to optimize immunogenicity in the elderly. The results show that high-dose quadrivalent vaccines (QIV-HD) and formulations with natural adjuvants improve immune response and reduce hospitalizations compared to standard doses. Coadministration of vaccines, such as influenza and COVID-19, is a safe practice that does not compromise the efficacy of each vaccine and facilitates vaccination in this high-risk population. The findings support the use of tailored vaccination strategies and underscore the need for additional studies to establish evidence-based recommendations for immunization in older adults.