International Journal of Clinical Case Reports, 2025, Vol.15, No.4, 190-199 http://medscipublisher.com/index.php/ijccr 192 2.3 The impact of chronic diseases on immunity The elderly often suffer from some chronic diseases, such as cardiovascular disease, diabetes, cancer and chronic kidney disease. These diseases will further aggravate immune aging and make the immune system worse. These diseases are usually accompanied by mild but long-term inflammation, accelerating immune aging and simultaneously affecting the body's response to foreign viruses or bacteria (Barbe-Tuana et al., 2020; Santoro et al., 2021). For instance, the immune aging of patients with chronic kidney disease is more pronounced, with high levels of inflammatory factors and aging of immune cells, which leads to a higher susceptibility to infection and poorer vaccine efficacy (Sato and Yanagita, 2019; Chi et al., 2022). There is mutual influence between chronic diseases and immune aging. Weakened immunity can aggravate chronic diseases, and chronic diseases can further damage immunity (Wang, 2024). This indicates that when caring for the elderly, both chronic diseases and immune problems must be paid attention to simultaneously in order to improve their overall health status (Sato and Yanagita, 2019; Barbe-Tuana et al., 2020; Santoro et al., 2021). 3 Types and Applicability of Influenza Vaccines 3.1 Common types of influenza vaccines Influenza vaccines for the elderly include conventional-dose inactivated vaccines (IIV), high-dose inactivated vaccines (HD-IIV), adjuvant vaccines (aTIV/aQIV), and recombinant vaccines (RIV). Trivalent (IIV3) and quadrivalent (IIV4) conventional vaccines are widely used. To enhance the immune response of the elderly, high-dose vaccine HD-IIV3, vaccine containing MF59 with adjuvant, and quadrivalent recombinant vaccine RIV4 have also been developed (Dunkle et al., 2017; Gartner et al., 2022; Veroniki et al., 2024). Recently, plant-derived virus-like particle vaccines and intradermal injection vaccines have also emerged, but these are used less frequently (Ng et al., 2018; Ward et al., 2020). High-dose and adjuvant vaccines enhance the immune response in the elderly by increasing the amount of antigens or using immune-enhancing components (Ng et al., 2018; Cunningham et al., 2021; Gartner et al., 2022). Recombinant vaccines are not produced using eggs and are suitable for people allergic to eggs. Moreover, they may be more effective when the virus mutates significantly (Dunkle et al., 2017; Veroniki et al., 2024). 3.2 Selection of vaccines for the elderly When choosing vaccines for the elderly, the issue of immune aging and their greater likelihood of contracting severe influenza should be taken into consideration. For people aged 65 and above, high-dose and adjuvant vaccines are usually more appropriate because they can trigger a stronger immune response and provide better protection than ordinary-dose vaccines (Diazgranados et al., 2014; Lee et al., 2018; Lee et al., 2020). Nowadays, many guidelines also recommend the use of this type of vaccine in institutions such as nursing homes, because once influenza breaks out in these places, the consequences are more serious (Ng et al., 2018; Cunningham et al., 2021; Gartner et al., 2022). The recombinant vaccine RIV4 is more effective than the common inactivated vaccine, especially when the vaccine and the epidemic virus do not match, and is suitable for vaccination in the elderly (Dunkle et al., 2017; Veroniki et al., 2024). Which vaccine to use specifically depends on an individual's physical condition, whether they have chronic diseases, and whether they can obtain this vaccine at that time (Diazgranados et al., 2015; Gartner et al., 2022). 3.3 Comparison of vaccine efficacy and applicability Both high-dose and adjuvant vaccines are more effective than conventional-dose vaccines in reducing laboratory-confirmed influenza, hospitalization, pneumonia and cardiopulmonary problems (Lee et al., 2018; Lee et al., 2020). For example, high-dose IIV3 reduced influenza cases by 24% more than regular IIV3, and the safety was similar (Diazgranados et al., 2014; Wilkinson et al., 2017). Real-world studies have also found that adjuvant vaccines are no less effective than high-dose vaccines, and even better, indicating that they are worthy of promotion among the elderly (Ng et al., 2018; Gartner et al., 2022).
RkJQdWJsaXNoZXIy MjQ4ODYzNA==