Journal of Vaccine Research, 2025, Vol.15, No.1, 1-9 http://medscipublisher.com/index.php/jvr 6 flocks. If biosecurity measures are inadequate or vaccine strains are prone to spread and mutate, this risk will be higher and even new pathogens with stronger toxicity may emerge. The spread of live vaccine strains in the environment is also a biosafety hazard, as these strains may spread to unvaccinated poultry and even wild birds, making disease prevention and control efforts more complicated. Strictly implementing vaccine handling norms, monitoring accidental transmission situations, and using inactivated vaccines or recombinant vaccines when necessary can reduce these risks (Badakaya et al., 2021). 5.3 Immunosuppression and mixed infections affecting vaccine efficacy Immunosuppression in poultry, whether due to stress, malnutrition, or concurrent infection with other diseases, will severely weaken the immune response triggered by vaccines, resulting in poorer protective effects and making poultry more prone to illness (Badakaya et al., 2021). If poultry are simultaneously infected with other pathogens, such as infectious bursal disease virus, mycoplasma, etc., it will further weaken the immunity brought by vaccines and make the condition more severe (Bhuiyan et al., 2021). The presence of immunosuppression or mixed infections in poultry highlights the importance of comprehensive management of poultry flock health, including ensuring good nutritional supply, implementing biosecurity measures, and regularly monitoring diseases. Only in this way can vaccines achieve the best effect and reduce the risk of vaccination failure (Badakaya et al., 2021; Bhuiyan et al., 2021). 6 Emerging Technologies and Future Development Directions 6.1 Promising technologies New achievements in the field of poultry vaccines include the development of RNA vaccines and the application of nanocarriers, which can precisely deliver antigens and enhance the immune effect. Nanotechnology means, such as virus-like particles (vlp), can simulate viral structures without genetic material, providing a safer and more immune-effective alternative to traditional vaccines (Raji et al., 2024). These innovations can make vaccines more stable, achieve precise delivery, and reduce the occurrence rate of adverse reactions. They are powerful tools for the future prevention and control of poultry diseases (Abdelaziz et al., 2024; Bodman-Harris et al., 2024). People are still exploring new vaccination systems, including follicular administration and new adjuvant formulations, to enhance vaccine absorption efficiency and immune response. Combining introvulation inoculation and large-scale inoculation methods with advanced vector platforms can efficiently carry out large-scale immunization and even holds the promise of preventing multiple pathogens with a single injection (Francis, 2021; Bodman-Harris et al., 2024). These technologies are expected to play a significant role in the prevention and control of existing and emerging infectious diseases in poultry (Abdelaziz et al., 2024). 6.2 Precision immunization and data-driven strategies Precision immunization optimizes vaccination plans through data-driven approaches, monitors herd immunity, strengthens disease prevention and control, and reduces vaccine waste. The use of digital tools for vaccine traceability enables real-time tracking of vaccine usage, batch information, and the health status of poultry flocks, which helps to respond quickly to the epidemic and enhance the effectiveness of the overall vaccination program (Abdelaziz et al., 2024). Personalized immunization plans tailored to different poultry flocks based on genetic, health and environmental data are becoming the development trend of poultry health management. These strategies can help determine the most applicable vaccine type, dose and vaccination time for each poultry flock, improve the protective effect, and reduce the risk of vaccine failure caused by factors such as maternal antibody interference and local pathogen variation (Ravikumar et al., 2022; Abdelaziz et al., 2024). 6.3 Enhance the efficacy of vaccines by integrating nutrition and genetic breeding Combining vaccination with nutritional intervention and genetic breeding is an overall strategy to ensure the health of poultry and enhance their disease resistance. Adjusting the feed formula and adding immune enhancers or probiotics can enhance the immune response triggered by vaccines and improve the overall resistance of the
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