Hepatitis B Virus Infection: Epidemiology and Vaccination

Worldwide, two billion people have been infected with hepatitisB virus (HBV), 360 million have chronic infection, and 600,000die each year from HBV-related liver disease or hepatocellularcarcinoma. This comprehensive review of hepatitis B epidemiologyand vaccines focuses on definitive and influential studies andhighlights current trends, policies, and directions. HBV canbe transmitted vertically, through sexual or household contact,or by unsafe injections, but chronic infections acquired duringinfancy or childhood account for a disproportionately largeshare of worldwide morbidity and mortality. Vaccination againstHBV infection can be started at birth and provides long-termprotection against infection in more than 90% of healthy people.In the 1990s, many industrialized countries and a few less-developedcountries implemented universal hepatitis B immunization andexperienced measurable reductions in HBV-related disease. Forexample, in Taiwan, the prevalence of chronic infection in childrendeclined by more than 90%. Many resource-poor nations have recentlyinitiated universal hepatitis B immunization programs with assistancefrom the Global Alliance for Vaccines and Immunization. Furtherprogress towards the elimination of HBV transmission will requiresustainable vaccination programs with improved vaccination coverage,practical methods of measuring the impact of vaccination programs,and targeted vaccination efforts for communities at high riskof infection. hepatitis B • hepatitis B vaccines • hepatitis B virus • immunization programs     

Vaccine Preventable Diseases and Vaccination Policy for Indigenous Populations

Compared with nonindigenous people, indigenous people in first-worldcountries have experienced much higher rates of many vaccinepreventable diseases. This systematic review of published scientificliterature, government reports, and immunization guidelinesfrom Australia, Canada, New Zealand, and the United States comparespre- and postvaccination disease rates and vaccination policyfor indigenous people in these four countries. Nationally fundeduniversal vaccination programs are clearly the most effectiveway of reducing disease in indigenous populations. Most successfulhave been programs for viral diseases in which strain variationsare not important and herd immunity is high, such as measlesand hepatitis B. For bacterial infections, strain variations(pneumococcal disease), heavy nasopharyngeal colonization ofyoung infants (pneumococcal and Haemophilus influenzae typeb disease), low vaccine effectiveness in adults with a highprevalence of risk factors (polysaccharide pneumococcal vaccine),and waning immunity (pertussis) have been associated with continuingor widening disparities between indigenous and nonindigenouspopulations. However, universal vaccination programs are notalways possible. Geographic targeting of all persons in certainregions with high disease rates has been successful, as hastargeting of indigenous populations in regions where they constitutelarger proportions of the population. In national programs targetingonly indigenous people, it has been difficult to achieve highcoverage, particularly in urban areas. Innovative program approachesare particularly needed in these situations. American Native continental ancestry group • communicable diseases • Haemophilus influenzae • hepatitis • immunization • influenza, human • Oceanic ancestry group • Streptococcus pneumoniae     

Hepatitis B virus infection among pregnant women in Taiwan: Comparison between women born in Taiwan and other southeast countries

Background  

Taiwan's national vaccination program has successfully decreased the prevalence of hepatitis B infection after twenty years of implementation and might be indirectly beneficial to the second generation. In this study, we compared the hepatitis B infection status of two groups: pregnant Taiwanese women and other Southeast Asian women, who because they had immigrated later in life to Taiwan by marriage to a Taiwanese man, had not been exposed to that vaccination program to evaluate the effect of hepatitis vaccination program on women of child-bearing age and further explored the potential impact of immigration on the hepatitis B public health policy in Taiwan.     

Hepatitis A in the Era of Vaccination

The World Health Organization estimates an annual total of 1.5million clinical cases of hepatitis A worldwide, but seroprevalencedata indicate that tens of millions of hepatitis A virus infectionsoccur each year. In the United States in the 1980s–1990s,an average of 26,000 acute hepatitis A cases were reported peryear, representing approximately 270,000 infections annually.Since licensure of effective hepatitis A vaccines in the mid-1990s,US hepatitis A rates have fallen precipitously—particularlysince 1999, when routine childhood vaccination was recommendedin states with consistently elevated rates. By 2004, the overallrate had declined to 1.9/100,000 population, the lowest rateever recorded and 79% lower than any previously recorded nadir.These marked declines occurred with relatively modest vaccinationcoverage, suggesting that strong herd immunity accompanies theinitiation of routine vaccination programs. Routine childhoodvaccination has produced similar results in Israel and selectedregions of Italy, Spain, and Australia. Hepatitis A vaccinationwill probably remain a low priority for some time in the poorestcountries, where most persons are infected as young children.However, shifts in the epidemiologic patterns of disease associatedwith declining hepatitis A virus transmission are occurringin many regions of the world. These shifts are likely to createcircumstances where strategically targeted vaccination of childrencould produce substantial public health benefits. hepatitis A • hepatitis A vaccine • hepatitis A virus • vaccines     

Measuring Immunization Coverage among Preschool Children: Past, Present, and Future Opportunities

Control of vaccine-preventable diseases depends on maintaininghigh levels of immunization coverage. Immunization coverageamong preschool children remains suboptimal in some areas andsociodemographic subgroups, as well as for more recently introducedvaccines, leaving susceptible young children vulnerable to complicationsfrom vaccine-preventable diseases. This paper reviews approacheshistorically used to measure immunization coverage among preschoolchildren in the United States. The strengths and weaknessesof various approaches to measuring immunization coverage amongpreschool children are explored, with emphasis on the currentmeans to measure national immunization coverage—the NationalImmunization Survey. Methods for measuring immunization coverageamong preschool children at local and state levels are alsoevaluated. Future opportunities and challenges for measuringimmunization coverage at the local, state, and national levelsare explored. child health services • child, preschool • communicable disease control • comparative study • immunization programs • immunization schedule • vaccination     

Measuring hepatitis B uptake in a new universal infant program

BACKGROUND: Vancouver-Richmond Health Board has the highest reported rate of hepatitis B in Canada, including an annual average of 25 cases in children under 12 years of age, based on reports from 1994-1997 inclusive. The current provincial adolescent grade-six hepatitis B immunization program does not protect against childhood infection. The regional health board implemented universal infant hepatitis B immunization in September 1998. METHOD: Immunization coverage data were obtained on a random sample of 191 infants born in March 1999 one year after initiation of the program. RESULTS: By eight months of age, 97.9% of children had received some vaccinations. 73.8% of infants had received three doses of hepatitis B vaccine and 12.6% had received two doses. In comparison, 89% had received three doses and 7.9% two doses of DPTP-Hib vaccine. 13.1% of infants had not received any hepatitis B vaccine. For a majority (67%) of these children, their physician's lack of awareness or lack of acceptance of the program constituted the reason for no hepatitis B vaccine uptake. Only one parent cited adverse publicity as the reason for refusing vaccination. INTERPRETATION: This survey reveals a successful first year of the program without harm to the pre-existing childhood vaccination programs. Hepatitis B vaccine uptake can be improved by increased awareness among physicians and parents.     

Epidemiological serosurvey of Hepatitis B in China—Declining HBV prevalence due to Hepatitis B vaccination

Objective

To determine the prevalence of hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (anti-HBs), and hepatitis B core anti-body (anti-HBc) in a representative population in China 14 years after introduction of hepatitis B vaccination of infants.

Methods

National serosurvey, with participants selected by multi-stage random sampling. Demographics and hepatitis B vaccination history collected by questionnaire and review of vaccination records, and serum tested for HBsAg, antibody to anti-HBc and anti-HBs by ELISA.

Findings

The weighted prevalences of HBsAg, anti-HBs and anti-HBc for Chinese population aged 1–59 years were 7.2%, 50.1%, 34.1%, respectively. HBsAg prevalence was greatly diminished among those age <15 years compared to that found in the 1992 national serosurvey, and among children age <5 years was only 1.0% (90% reduction). Reduced HBsAg prevalence was strongly associated with vaccination among all age groups. HBsAg risk in adults was associated with male sex, Western region, and certain ethnic groups and occupations while risk in children included birth at home or smaller hospitals, older age, and certain ethnic groups (Zhuang and other).

Conclusions

China has already reached the national goal of reducing HBsAg prevalence to less than 1% among children under 5 years and has prevented an estimated 16–20 million HBV carriers through hepatitis B vaccination of infants. Immunization program should be further strengthened to reach those remaining at highest risk.     

Hepatitis B vaccination coverage of Vietnamese children in south-western Sydney

Vaccination coverage since the selective hepatitis B vaccination of neonates of highrisk group program introduced in 1987, was measured in 658 children from 301 Vietnamese families living in the southwestern Sydney. The vaccination rate of children born after the introduction of the program was twice that of children born before its implementation (OR=2.00, 95% Cl 1.65–2.42). The shorter the mother's duration of residency in Australia, the more likely her children were to be fully vaccinated (OR=2.49, 95% Cl 2.43-2.62). A catch-up vaccination program of older siblings is required to assist the public health strategy to reduce the morbidity and mortality from hepatitis B viral infection.     

Interdisciplinary Epidemiologic and Economic Research Needed to Support a Universal Childhood Influenza Vaccination Policy

Recent research indicates that influenza vaccination of childrenmay decrease the influenza disease burden in adults to a greaterextent than targeting vaccination to populations at high riskof serious disease. Possible new policies reflecting these resultswould add groups most likely to transmit disease to existingvaccination recommendations. Interdisciplinary research combiningepidemiology with economics is needed to answer critical questionsabout the desirability and feasibility of potential new policies,such as what additional resources medical providers might needto expand vaccination to larger groups or what opportunity costsparents might incur in vaccinating their children annually.In this paper, the authors provide background for some of thechanges in influenza vaccination rates and disease and discussexisting information gaps and research methods capable of closingthese gaps. They provide several examples of interdisciplinarystudies that have incorporated both economics and epidemiologyor health policy issues. These studies are representative ofa variety of stakeholder perspectives needed to determine whethercommunity-based, universal childhood vaccination policies wouldbe more efficacious and cost-effective than strategies targetedtoward persons at high risk of disease complications. economics • health policy • influenza vaccines • mass immunization • policy making • public health • research     

Reduction in hepatitis B virus seroprevalence among U.S.-born children of foreign-born Asian parents—Benefit of universal infant hepatitis B vaccination

We demonstrate that after implementation of recommendations for universal infant hepatitis B vaccination, HBV infection prevalence among children of foreign-born Asian parents in Georgia declined dramatically; horizontal transmission of infection within households has occurred infrequently; and the vast majority of infants and children have received the recommended hepatitis B vaccinations. These results provide evidence of the success of the hepatitis B infant vaccination program and highlight its potential impact on reducing chronic HBV infection morbidity and mortality among U.S. populations at high risk.     

Hepatitis B vaccination among high-risk adolescents and adults--San Diego,California, 1998-2001

The national strategy to eliminate hepatitis B virus (HBV) transmission is based on 1) screening all pregnant women for hepatitis B surface antigen and post-exposure vaccination of infants of infected mothers; 2) vaccinating all infants as part of the childhood vaccination schedule; 3) vaccinating children and adolescents not vaccinated previously; and 4) vaccinating adolescents and adults in groups at increased risk for infection. These strategies have been implemented successfully in the United States except for the vaccination of adults and older adolescents at high risk. This report describes the initial findings of a hepatitis B vaccination program for potentially high-risk adolescents and adults conducted in areas of San Diego County, California. The findings indicate that high rates of hepatitis B vaccination can be achieved in clinics and programs that serve persons at high risk for HBV infection through the integration of hepatitis B vaccination into routine preventive health-care services. Improved efforts to vaccinate adolescents and adults at increased risk for HBV infection are critical to reduce disease incidence and prevent chronic HBV infection.     

Design of a robust infrastructure to monitor the safety of the pandemic A(H1N1) 2009 vaccination program in Taiwan

On November 1, 2009, Taiwan began a nationwide pandemic A(H1N1) 2009 vaccine (“H1N1 vaccine”) program to control the influenza pandemic. Timely assessment of immunization safety during this mass vaccination campaign was a public health priority. Therefore, the government developed a national postlicensure safety surveillance strategy to identify and evaluate new, unexpected, or prioritized adverse events in recipients of H1N1 vaccine in near real-time. We describe the design and methodology of this new safety assessment infrastructure, address challenges encountered, and its potential future use for routine vaccine pharmacovigilance in Taiwan.     

Low seroprevalence of hepatitis B surface antibody among nursing students in Taiwan: an implication for boosting

The national hepatitis B vaccination program in Taiwan began in July 1984. The purpose of this repeated survey was to investigate the levels of anti-HBs (hepatitis B surface antibody) in the first-year students of a 5-year nursing program in Taiwan. Each year during 2000-2006, the entering students of the 5-year nursing program at Fooyin University, a vocational university located in southern Taiwan, were examined for their HBsAg and anti-HBs status using commercially available microparticle enzyme immunoassay. The seroprevalence of HBsAg (+) showed a significant trend of decrease, dropping 57% from 4.9% in 2000 to 2.1% in 2006. The seroprevalence of anti-HBs (+) also showed a significant trend of decrease, dropping 49% from 77.1% in 2000 to only 39.7% in 2006. With the relatively low seroprevalence of anti-HBs (+) of the future healthcare workers and high HBV endemicity in Taiwan, recommendation of serology test before boosting to nursing students before they proceed their clinical practice is prudent.     

Hepatitis B vaccination coverage among adults--United States, 2004

Hepatitis B virus (HBV) infection is a major cause of cirrhosis and liver cancer in the United States. The Advisory Committee on Immunization Practices (ACIP) has recommended a comprehensive strategy to eliminate HBV transmission, including prevention of perinatal HBV transmission; universal vaccination of infants; catch-up vaccination of unvaccinated children and adolescents; and vaccination of unvaccinated adults at increased risk for infection. The incidence of acute hepatitis B has declined 75%, from 8.5 per 100,000 population in 1990 to 2.1 per 100,000 population in 2004, with the greatest declines (94%) among children and adolescents. Incidence remains highest among adults, who accounted for approximately 95% of the estimated 60,000 new infections in 2004. To measure hepatitis B vaccination coverage among adults, data were analyzed from the 2004 National Health Interview Survey (NHIS). This report summarizes the results of that analysis, which indicated that, during 2004, 34.6% of adults aged 18-49 years reported receiving hepatitis B vaccine, including 45.4% of adults at high risk for HBV infection. To accelerate elimination of HBV transmission in the United States, public health programs and clinical care providers should implement strategies to ensure that adults at high risk are offered hepatitis B vaccine.     

Vaccine-preventable disease control in the People’s Republic of China: 1949–2016

BackgroundChina's immunization program is one of the oldest and largest in the world. Rates of vaccine-preventable diseases (VPD) are comparable to those in high-income countries. The program's evolution has been characterized by ambitious target setting and innovative strategies that have not been widely described.MethodsWe reviewed national and provincial health department archives; analyzed disease surveillance, vaccination coverage, and serosurvey data from 1950 through 2016; and, conducted in-depth interviews with senior Chinese experts involved early VPD control efforts.ResultsWidespread immunization began in the 1950s with smallpox, diphtheria, and Bacillus-Calmette Guerin vaccines, and in the 1960s with pertussis, tetanus, polio, measles, and Japanese encephalitis (JE) vaccines. The largest drops in absolute VPD burden occurred in the 1970s with establishment of the Rural Cooperative Medical System and a cadre of trained peasant health workers whose responsibilities included vaccinations. From 1970 to 1979, incidence per 100,000 population dropped 48% from 3.3 to 1.75 for diphtheria, 50% from 152.2 to 49.4 for pertussis, 77% from 2.5 to 0.6 for polio, 60% from 450.5 to 178.3 for measles, and 72% from 18.0 to 5.1 for JE, averting an average of 4 million VPD cases each year. Until the early 1980s, vaccines were delivered through annual winter campaigns using a coordinated ‘rush-relay’ system to expedite transport while leveraging vaccine thermostability. Establishment of the cold chain system during in the 1980s allowed bi-monthly vaccination rounds and more timely vaccination resulting in rates of diphtheria, pertussis, measles and meningitis falling over 90% from 1980 to 1989, while polio and JE rates fell 40–50%. In the 1990s, progress stalled as financing for public health was weakened by broad market reforms. Large investments in public health and immunizations by the central government since 2004 has led to further declines in VPD burden and increased equity. During 2011–2016, the incidence per 100,000 population was <2.0 for measles and <0.2 for pertussis, JE, meningococcal meningitis, and hepatitis A. From 1992 to 2014, the prevalence of chronic hepatitis B infection in children <5 years fell from 9.7% to 0.3%, a 97% decline. China was certified polio-free in 2000 and diphtheria was last reported in 2006.ConclusionsLong-term political commitment to immunizations as a basic right, ambitious targets, use of disease incidence as the primary metric to assess program performance, and nationwide scale-up of successful locally developed strategies that optimized use of available limited resources have been critical to China's success in controlling vaccine-preventable diseases.     

Knowledge,attitudes, and practices regarding hepatitis B vaccination among hospital-based doctors and nurses in China: Results of a multi-site survey

BackgroundHepatitis B virus (HBV) can cause chronic HBV infection, which may lead to advanced cirrhosis and liver cancer. Healthcare workers (HCWs) are at risk HBV infection as an occupational hazard. Hepatitis B vaccination of HCWs is recommended by WHO, but the status of hepatitis B vaccination among HCWs in China is seldom reported.MethodologyWe conducted a cross-sectional study in 22 hospitals of 3 developed cities in China. We interviewed managers in infectious diseases and occupational health departments, and at least 40 HCWs per hospital.ResultsWe interviewed 929 HCWs; 80.8% were vaccinated against hepatitis B and 96.7% were willing to be vaccinated; 38.2% of HCWs reported having at least one needle stick or sharps injury. Three hospitals provide free hepatitis B vaccination for HCWs; hospitals with a hepatitis B vaccination policy, more HCWs reported being vaccinated (91.7% vs 79.0%, P < 0.001). HCWs in high risk departments (P = 0.011), with more knowledge of hepatitis B vaccine (P < 0.001), and with fewer working years (P = 0.002) were more likely to be vaccinated against HBV. Infectious diseases and occupational health managers had positive attitudes towards hepatitis B vaccination.ConclusionsHepatitis B vaccination was well accepted among HCWs. Hospital provision of free vaccine, greater HCW knowledge of HBV, and working in higher-risk settings were associated with being vaccinated. A national policy of offering hepatitis B vaccine to HCWs should be considered in China. Provision of free hepatitis B vaccine for HBsAb negative HCWs may be acceptable. Education about HBV and hepatitis B vaccine may help promote policy implementation.     

The shifting epidemiology of hepatitis A following routine childhood immunization program in Israel

OBJECTIVES: In 1999 Israel became the first country to introduce immunization against hepatitis A to its national childhood vaccination program. The study objectives were to assess the uptake of hepatitis A vaccine following the new policy and to examine the incidence of hepatitis A and the number of prevented cases. METHODS: Data on incidence of hepatitis A and vaccination rates were obtained from a large health maintenance organization in Israel covering 1.6 million members. We identified all members that were diagnosed by a primary care physician as suffering from hepatitis A, had a positive hepatitis A virus-IgM test result, or were hospitalized due to hepatitis A between 1998 and 2004. RESULTS: The results indicate that 5 years following its inclusion in the national childhood immunization program, vaccination coverage levels with at least one dose of hepatitis A vaccine for children aged under 5 years and 5-14 years were 87% and 51%, respectively. During this period the annual incidence rates declined by 88% from 142.4 to 17.3 per 100,000. The most significant reduction in morbidity was observed among children. CONCLUSIONS: In endemic areas, vaccination of infants and children against hepatitis A may be efficient to greatly reduce the total burden of the disease.     

Hepatitis B in children in Italy: Incidence and risk factors

The objectives of the present report were to give a baseline picture of hepatitis B notification incidence rates in children before the campaign of mass vaccination for newborns and adolescents (12–13 years old), and to study the role of different risk factors. Data from a specific national surveillance system of acute viral hepatitis (SEIEVA, Sistema Epidemiologico Integrato dell'Epatite Virale Acuta) were used and acute hepatitis B cases were compared to acute hepatitis A patients with the case-control study method to estimate the associations with the considered risk factors. Since the system began, one hundred and sixty-three local health departments have joined SEIEVA covering 30% of the Italian population. The incidence of acute hepatitis B notifications among 0–14 aged children was 9 per 100,000 in 1985 and 1 per 100,000 in 1990. Such decline in incidence was observed in both the North and the South of Italy. Surgical interventions, dental therapy and household contacts with a HBsAg chronic carrier were found to be associated with acute hepatitis B. The point estimate of the odds ratio was 10 for the latter risk factor. Other preventive measures in addition to vaccination are needed to control the risk of hepatitis B infection and other parenteral diseases due to surgical intervention and dental therapy.     

Post-vaccination serological test results of infants at risk of perinatal transmission of hepatitis B using an intensified follow-up programme in a London centre

Immunisation of infants born to hepatitis B virus (HBV) infected mothers is an important public health measure to prevent mother-to-child transmission of HBV. Post-vaccination serological tests (PVST) inform the success of the infant HBV immunisation programme and identify infected infants. Previous studies suggested that the rates of PVST in the UK programme were unsatisfactory. We introduced an intensified local follow-up programme and offered an earlier PVST 2–3 months after the third vaccination at age 4–5 months. Of 219 infants born between 2009 and 2011, 193 infants (88.1%) had at least one PVST: 145 (66.2%) early; 94 (42.9%) standard; 46 (21.0%) both and 26 (11.9%) never tested. Twenty-four infants were identified as high risk for mother-to-child transmission according to national criteria and received both hepatitis B immunoglobulin (HBIG) and hepatitis B vaccine at birth. These infants had a significantly lower hepatitis B surface antibody (anti-HBs) levels at early PVST compared to the lower risk group who received hepatitis B vaccine only (median of 59 vs. 376 mIU/ml, P = 0.006). None of the infants tested were infected with hepatitis B. This study illustrates that the rate of PVST can be improved by using an intensified follow-up programme offering an early PVST. The significantly lower anti-HBs levels in the HBIG subgroup is of concern as this group of infants is already at higher risk for acquiring HBV infection. Infants with poor antibody responses can be identified by an early PVST and offered a timely extra booster dose.     

Knowledge,attitudes, beliefs,and behaviors of parents and healthcare providers before and after implementation of a universal rotavirus vaccination program

ObjectiveIn Canada, rotavirus vaccine is recommended for all infants, but not all provinces/territories have publicly funded programs. We compared public and healthcare provider (HCP) knowledge, attitudes, beliefs, and behaviors in a province with a public health nurse-delivered, publicly funded rotavirus vaccination program to a province with a publicly funded, physician-delivered program. A third province with no vaccination program acted as a control.DesignInformation about knowledge, attitudes, beliefs, and behaviors of parents whose children were eligible for the universal program and healthcare providers responsible for administering the vaccine were collected through the use of two validated surveys distributed in public health clinics, physicians’ offices, and via e-mail. Early and postvaccine-program survey results were compared.ResultsA total of 722 early implementation and 709 postimplementation parent surveys and 180 early and 141 postimplementation HCP surveys were analyzed. HCP and public attitudes toward rotavirus vaccination were generally positive and didn’t change over time. More parents postprogram were aware of the NACI recommendation and the vaccination program and reported that their healthcare provider discussed rotavirus infection and vaccine with them. Prior to the program across all sites, more physicians than nurses were aware of the national recommendation regarding rotavirus vaccine. In the postprogram survey, however, more nurses were aware of the national recommendation and their provincial universal rotavirus vaccination program. Nurses had higher knowledge scores than physicians in the postprogram survey (p < 0.001). Parents of young infants were also more knowledgeable about rotavirus and rotavirus vaccine in the two areas where universal programs were in place (p < 0.001).ConclusionsImplementation of a universal rotavirus vaccination program was associated with an increase in knowledge and more positive attitudes toward rotavirus vaccine amongst parents of eligible infants. Nurses involved in a public health-delivered vaccination program were more knowledgeable and had more positive attitudes toward the vaccine than physicians in a jurisdiction where vaccine was physician-delivered.