Journal of Vaccine Research, 2025, Vol.15, No.1, 10-22 http://medscipublisher.com/index.php/jvr 17 elderly and those with weakened immunity can make up for their weak immune response by increasing vaccine doses, using vaccines with added auxiliary components, or choosing specific primary and booster combinations (Radošević et al., 2009; Cheng et al., 2022). With the development of systems biology and genetic testing technology, we can identify those who do not respond well to vaccination, and then customize exclusive vaccination times, vaccine types and booster shot regimens based on their conditions (Radošević et al., 2009). This precise vaccination strategy not only enables the vaccine to exert its maximum protective effect and minimize side effects, but also ensures that everyone can fairly enjoy the protective benefits of the vaccine. 8 Future Development Directions and Research Gaps 8.1 A deeper understanding of the maintenance of memory cells is required Although memory B cells and T cells are crucial for the long-term immunity brought by vaccines, we have not yet fully understood how they are produced, remain active and reactivated (Palm and Henry, 2019; Liu et al., 2023; Syeda et al., 2024; Li et al., 2024). There are still many key issues that have not been clarified, such as which internal and external factors can enable long-lived plasma cells and memory T cells remaining in tissues to survive, including what specific signals they need to maintain activity and in what kind of environment they can survive (Macallan et al., 2017; Takamura, 2018; Khodadadi et al., 2019; Reusch and Angeletti, 2023). Recent studies have found that there are a wide variety of memory cells, and their different living environments have a significant impact on them. However, we have not yet fully understood exactly what mechanism is controlling the survival and changes of these cells (Macallan et al., 2017; Takamura, 2018). Filling these knowledge gaps is of great significance for developing vaccines that can reliably produce long-term immune effects and for finding indicators that can predict long-term immune protection (McGrath et al., 2022; Reusch and Angeletti, 2023; Syeda et al., 2024). 8.2 Improvements in the design of next-generation vaccines and drug delivery platforms With new progress in our research on memory cells, there is a direction for developing the next generation of vaccines, with the goal of enabling vaccines to trigger broader and more lasting immune responses (McGrath et al., 2022; Li et al., 2024; Syeda et al., 2024). Scientists are researching new vaccine technologies, such as using new auxiliary components or trying new vaccination methods (like vaccines targeting mucous membranes or specific tissues), hoping to better stimulate the memory cells remaining in the tissues and enhance the immune protection ability of the body's barrier sites (Wilk and Mills, 2018; Reusch and Angeletti, 2023). However, it is still very difficult to apply the results of animal experiments to humans, especially in terms of accurately measuring and targeting memory cell groups in specific tissues (Palm and Henry, 2019). Only by deeply understanding how memory cells are generated and maintained, and constantly innovating vaccine formulations and vaccination methods, can we break through the current limitations and solve those diseases that were previously impossible to effectively prevent (Wilk and Mills, 2018; Reusch and Angeletti, 2023; Syeda et al., 2024) 8.3 Establish a long-term population follow-up and predictive modeling system We need to conduct long-term follow-up studies and establish predictive models so as to better understand how long the immune effect produced by vaccines in the population can last. Through these studies, factors leading to weakened immunity can be identified, and the survival time of memory cells can be observed, providing a basis for formulating booster immunization strategies and updating vaccines (Macallan et al., 2017; Palm and Henry, 2019). If a sound long-term monitoring system can be established and the changes of memory cells can be incorporated into the dynamic model, the effectiveness of vaccines at different times can be predicted more accurately (Macallan et al., 2017). These methods are crucial for formulating reasonable vaccination policies, especially when dealing with emerging pathogens and the constantly changing epidemic situation of diseases.
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