University of California
Type of paper: Thesis/Dissertation Chapter
Hepatitis B epidemiology and prevention strategies
Hepatitis B is a serious viral infection which is characterized by hepatic cell inflammation and disturbed liver functioning and is associated with high morbidity and mortality rates. It is a disease known to mankind since antiquity, given that cases of epidemic jaundice are reported in ancient Chinese documents as well as in Hippocrates’ writings in the 5th century B. C. Similar epidemics have been described during the Medieval and the Renaissance years, however, the first recorded cases of hepatitis B are probably dated in 1883 in German shipyard workers following the administration of small pox vaccine.
In 1965, Blumberg identified a specific antigen in the serum of an Australian Aborigine, named “Australia antigen”, which was later linked to hepatitis B. Its detection allowed the accurate diagnosis of HBV infection, expanded scientific knowledge on the field and led to effective prevention and treatment strategies (Mahmoud Al-Hussami, 2004). According to World Health Organization, hepatitis B affects almost 2 billion people worldwide, which represents one third of global population.
75% of the world population live in areas of high endemicity, thus being exposed to high infection risk. (Previsani et al, 2002). In its chronic form, the infection affects almost 350 million individuals and may lead to several major complications including liver cirrhosis and failure and hepatocellular carcinoma, thus having an adverse effect on patients’ survival and quality of life (Lok, 2002; Rantala, 2008).
Recent epidemiological and clinical data reveal that up to 80% of primary liver tumors worldwide can be attributed to chronic HBV infection (Lavanchy et al, 2004). It is estimated that hepatitis B is responsible for one million deaths annually, half of which are associated with hepatocellular carcinoma. In addition, economotechnical studies worldwide reveal that chronic hepatic B patients require long and frequent hospitalizations thus posing a significant financial burden on national health care systems (Pantazis et al, 2008).
There is great variation in hepatitis B prevalence rates worldwide. The disease is more prevalent in developing countries, including tropical Africa, Southeast Asia and China, where 10-15% of the general population are HBsAg carriers (Previsani et al, 2002). In contrast, developed countries with higher standards of living and better organized public health systems, are considered areas of low endemicity for the disease. In Western and Central Europe, North America and Australia, seroprevalence rates range from 0. 2 to 1. 5% of the general population.
In these areas, young adults are mostly affected, with males having 1. 8 greater risk to be infected compared to females. It is estimated that 200,000-300,000 individuals in the United States become infected with HBV annually, and almost one million people are chronically infected. Despite, HBV infection’s low prevalence, there are certain sub-populations in the Western world that run extremely high risk compared to the general population.
These high-risk groups include infants born to infected mothers, healthcare workers, intravenous drug users, individuals living with HBV patients, sexually active heterosexuals with multiple partners, homosexual males, haemodialysis patients and patients frequently receiving blood transfusions (Previsani et al, 2002). The existence of a sub-population of vulnerable individuals, underlines the fact that hepatitis B remains a small yet appreciable public health risk and emphasizes the need for proper interventions.
WHO suggests specific measures aiming at HBV infection surveillance and disease control. Although in most countries reporting HBV infection is mandatory, a significant percentage of cases go under-reported and surveillance systems need to be upgraded. In addition, effective disease control should encompass broadening of immunization, effective screening of blood and blood products to avoid transmission through transfusion and educating healthcare workers and high-risk individuals (Previsani et al, 2002).
After the introduction of HBV vaccine in 1981, the systematic implementation of national vaccination programs in developed countries has led to a significant decrease in seroprevalence. By the end of the year 2007, 171 countries had instituted the systematic vaccination of infants . HBV vaccine represents a safe and highly effective method of immunization which protects against hepatitis B and its long-term complications in 95% of cases (Previsani et al, 2008). Initially, HBV vaccine was a plasma derived product, however due to concerns regarding the possibility of viral transmission, it was substituted by the recombinant form.
The current trend in hepatitis B vaccination supported by the Center for Disease Control (CDC) is to target not solely high risk individuals but also all newborns, children and adolescents up to 18 years of age, given that in a significant proportion (30%) of acute HBV infections no risk factor can be traced. However, despite the vaccine’s established efficacy, vaccination programs’ success is currently limited by the existence of a sizeable percentage of individuals who refuse to be vaccinated. Several studies worldwide have revealed that vaccination rates among healthcare workers hardly reach 50% (CDC, 1991).
Likewise, in earlier and recent studies, parents reported significant doubts about global infant immunization (Woodruff et al, 1996; Hontelez et al, 2010). A recent German study reported vaccination rates of 29% for the general population and 58% for high risk groups, revealing a significant gap in vaccination coverage (Schenkel et al, 2008). Parameters which have consistently been shown to relate to vaccination acceptance include higher educational level, younger age and better information about the disease (Mahmoud Al-Hussami, 2004; Panhotra et al, 2005).
Additional reasons for low vaccination compliance may be associated with vaccine availability and cost. Despite their growth and prosperity and the development of welfare state, western societies still have to cope with the fact that a sizeable proportion of the population lacks access to basic healthcare, due to financial and social reasons. These findings underscore the importance of informing and educating the public opinion about hepatitis B and widening the availability of HBV vaccine.
In order to implement an effective vaccination campaign, people should be responsibly informed regarding risk factors, ways of transmission and prevention measures. In this way, not only vaccination acceptance will rise, but, in addition, individuals will be encouraged to adopt a healthier lifestyle, including embracing basic hygiene habits, condom use and other safe sex practices in everyday life. Previous research has shown that using the internet and the mass media to provide disease-related information may have a positive impact on disease prevention (Kang et al, 2010).
In addition, school-based programs have proven adequately efficacious in modifying negative parental attitudes towards immunization thus increasing vaccination rates. (Ogilvie et al, 2010). Insurance providers are strongly encouraged to undertake similar educational initiatives targeting the whole population to minimize disease’s medical, psychosocial and financial impact. Lowering vaccine cost and rendering it accessible to the whole population requires additional funding and strong policy makers, determined to defend public safety and well-being against economic gain and pharmaceutical companies’ agendas.
In the USA, the price of vaccination per dose ranges from 15 to 41 U. S. dollars, depending on the context where it takes place, and emerges as a major barrier to immunization. However, even in countries of low endemicity, such as the USA, universal immunization programs appear cost-effective, given the significant burden imposed by the disease and its long-term complications in terms of financial and human resources (Previsani et al, 2002).
When coping with public health issues, preventive approaches represent more efficacious and cost-effective strategies compared to treatment plans, and in this respect, insurance providers may economize in the long run by covering vaccination’s cost. Another important measure for disease control is the implementation of systematic screening of blood and blood products. Modern screening practices based on recent advances in immunochemistry and molecular biology have significantly decreased HBV transmission through blood transfusion, however, there remains a small percentage of cases where HBV can not be detected.
These cases represent a significant risk for multi-transfused patients, a risk which can be eliminated through educating and encouraging blood donors to keep a responsible and sensitive stance. Avoiding donating blood when engaging in high risk behaviors is probably the more simple and effective way of reducing the risk of HBV infection through blood transfusion. In conclusion, hepatitis B represents a major public health condition worldwide, associated with severe complications, poor quality of life and increased mortality rates.
National and international organizations have addressed the issue, raising public and individual awareness and encouraging wide-scale immunization programs. However, significant obstacles have been detected in the implementation of disease prevention strategies, including difficulties in repudiating high-risk behaviors and adopting a healthier way of living, and limited availability and acceptance of the vaccine. In this respect, policy makers can maximize the efficacy of HBV prevention, by providing accurate and valid information to the public and increasing people’s access to vaccination.