Journal of Vaccine Research 2024, Vol.14, No.3, 107-119 http://medscipublisher.com/index.php/jvr 110 The burden of HBV-related morbidity and mortality is not evenly distributed across the globe. Regions with high HBV endemicity, such as sub-Saharan Africa and East Asia, experience higher rates of chronic infection and related complications. For instance, in East Asia, the prevalence of HBsAg (a marker of chronic HBV infection) can be as high as 8.6% (Ott et al., 2012). The implementation of universal vaccination programs has led to significant reductions in HBV-related morbidity and mortality in many regions. For example, in Taiwan, the prevalence of chronic HBV infection in children has declined by more than 90% following the introduction of universal vaccination (Kao and Chen, 2002; Shepard et al., 2006). 3.3 Economic and social burden The economic and social burden of HBV is profound. The direct medical costs associated with managing chronic HBV infection, cirrhosis, and HCC are substantial. These costs include expenses for antiviral treatments, liver transplantation, and ongoing medical care. In addition to direct medical costs, there are significant indirect costs related to lost productivity, as individuals with chronic HBV may experience reduced work capacity and early mortality (Locarnini et al., 2015; Hutin et al., 2018). The social burden of HBV extends beyond the affected individuals to their families and communities. Stigma and discrimination against individuals with HBV can lead to social isolation and mental health issues. In many regions, particularly those with high HBV prevalence, there is a lack of awareness and understanding about the disease, which can hinder efforts to prevent and manage HBV infection effectively (Locarnini et al., 2015; Pattyn et al., 2021). Vaccination remains the most cost-effective strategy to reduce the economic and social burden of HBV. Universal vaccination programs have been shown to be highly effective in preventing new infections and reducing the prevalence of chronic HBV. For instance, the World Health Organization (WHO) recommends the inclusion of the hepatitis B vaccine in national immunization programs, which has led to significant reductions in HBV-related morbidity and mortality in many countries (Zanetti et al., 2008; Hutin et al., 2018). However, challenges remain in achieving high vaccination coverage, particularly in low-resource settings where economic and social barriers can impede the implementation of vaccination programs (Kao and Chen, 2002; Zanetti et al., 2008). The health impact of hepatitis B is multifaceted, encompassing acute and chronic infections, significant morbidity and mortality, and substantial economic and social burdens. Effective vaccination strategies are crucial in mitigating these impacts and moving towards the global elimination of HBV as a public health threat. Continued efforts are needed to overcome the barriers to vaccination and ensure that all individuals, regardless of their geographic or socioeconomic status, have access to life-saving vaccines. 4 Current Vaccination Strategies 4.1 Vaccine development and types The development of hepatitis B vaccines has been a cornerstone in the fight against hepatitis B virus (HBV) infection. The first licensed hepatitis B vaccine was derived from the purification of hepatitis B surface antigen (HBsAg) from the plasma of asymptomatic carriers. This was followed by the advent of recombinant DNA technology, which enabled the production of recombinant hepatitis B vaccines. These vaccines are highly effective, providing long-term protection against HBV infection in more than 90% of healthy individuals who complete the vaccination series (Zhao et al., 2020; Pattyn et al., 2021). The standard hepatitis B vaccination schedule typically involves three doses, which can elicit long-term immunity lasting over 30 years. Additionally, the concurrent use of hepatitis B immunoglobulin (HBIG) and the hepatitis B vaccine has significantly reduced mother-to-child transmission (MTCT) of HBV. This combination has been particularly effective, reducing the infection rate to nearly zero in children born to HBsAg-negative mothers and to 5-10% in children born to HBsAg-positive mothers (Zhao et al., 2020). Despite these advancements, there are still challenges in vaccine implementation, particularly in regions with suboptimal vaccination coverage. Efforts are ongoing to improve the global reach of hepatitis B vaccination, especially in resource-poor settings where the burden of HBV is highest (Table 1) (Zhao et al., 2020; Pattyn et al., 2021).
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