Journal of Vaccine Research 2024, Vol.14, No.4, 170-182 http://medscipublisher.com/index.php/jvr 175 Figure 2 Forest Plot of Vaccine Efficacy (VE) of the TAK-003 Vaccine Across Different Regions and Age Groups (Adapted from Rivera et al., 2022) Image caption: The study compares the efficacy of the vaccine group versus the placebo group in preventing virologically confirmed dengue (VCD), hospitalized VCD, severe dengue, and dengue hemorrhagic fever (DHF). The results indicate that the vaccine provides higher protection against hospitalized VCD across all regions and age groups, with particularly notable efficacy in individuals who were seropositive at baseline. Although VE varied by region and dengue serotype, the vaccine showed better protection against DENV-1 and DENV-2, while offering lower protection against DENV-3 in baseline seronegative individuals. Additionally, over the 3-year follow-up period, the vaccine demonstrated effectiveness in preventing severe dengue and DHF (Adapted from Rivera et al., 2022) While pre-existing immunity enhances the efficacy and safety of dengue vaccines, it also complicates vaccine deployment strategies, particularly in areas with varying levels of dengue transmission. Future vaccine strategies must consider these factors to optimize protection and minimize risks, especially in vulnerable populations. 5 Safety Concerns and Regulatory Issues 5.1 Safety profile of leading vaccines The safety profile of dengue vaccines has been a critical factor in their development and regulatory approval. Clinical trials of leading dengue vaccines, such as Dengvaxia (CYD-TDV) and TAK-003, have provided extensive data on adverse effects and overall safety. Dengvaxia, the first dengue vaccine to be approved, demonstrated a generally favorable safety profile in initial trials. Most adverse effects were mild to moderate, including injection site reactions, fever, headache, and myalgia. However, more serious safety concerns emerged, particularly in seronegative individuals who received the vaccine. These individuals were found to have an
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