Hepatitis B: vaccination programmes in Europe--an update

In the eight years since the Global Advisory Group of the Expanded Program on Immunisation set 1997 as the target for integrating hepatitis B (HB) vaccination into national immunisation programs world-wide, more than 116 countries have included HB vaccine as part of their routine infant or adolescent immunisation programs. Meanwhile, many countries have performed economic evaluation studies, while others have initiated sero-epidemiological studies to generate input data for burden of disease calculation. These studies have indicated that epidemiological and economic arguments cannot be used to delay the implementation of universal hepatitis B vaccination. Some countries have improved their surveillance system and included viral hepatitis in the surveillance programs. Other have put hepatitis B vaccination on the political agenda. By the year 2000, following countries of the WHO European Region (51 countries) have implemented a universal hepatitis B immunisation programme: Andorra, Albania, Austria, Belarus, Belgium, Bulgaria, Estonia, France, Germany, Greece, Italy, Israel, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Luxembourg, Malta, Moldova, Monaco, Poland, Portugal, parts of the Russian Federation, Romania, Slovakia, Slovenia, San Marino, Spain, Switzerland, Turkey and Uzbekistan. The Netherlands and some other European countries are seriously studying the issues or are making budgetary provisions for introduction of HB vaccine into their vaccination programme. Most of the European countries, which now use the vaccine routinely, have started with adolescent or infant immunisation. Belgium (1999), France (1994) and Italy (1991) have begun with both adolescent and infant HB immunisation. France continues since 1st October 1998 with the infant immunisation programme only. The rewards of effective implementation of the programmes in these countries are becoming apparent; and their success offers an exemplary model for other countries. The deadline was 1997. Globally, work still remains to be done to support and implement interventions that will bring us closer to the WHO goal and to control, eliminate and eradicate hepatitis B in the coming generations at large. If all the 145 million infants born in 1991 had been vaccinated in this way, the number of chronic carriers would have been reduced by 7.5 million, and 1.8 million deaths prevented.     

Vaccination programs for pregnant women in Europe, 2021

Vaccination during pregnancy is increasingly adopted worldwide in order to protect the mother and her offspring. We studied the current vaccination programs specifically for pregnant women in 42 European countries. Vaccination programs for pregnant women are in place in 37 countries, as follows: influenza (36 countries), pertussis (28), hepatitis B (12), tetanus (10), pneumococcal disease (10), meningococcal disease (10), rabies (8), tick-borne encephalitis (6), hepatitis A (5), poliomyelitis (4), diphtheria (3), Haemophilus influenzae (2), and human papilloma virus (1). Recommendations for vaccination against influenza and pertussis concern almost exclusively pregnant women regardless of high-risk conditions, however differences between vaccination recommendations are noted in terms of timing. Vaccinations against hepatitis B, hepatitis A, pneumococcal disease, meningococcal disease, poliomyelitis, H. influenzae, rabies, and tick-born encephalitis mainly concern pregnant women at high-risk for exposure or serious illness and post-exposure vaccinations. Overall, five European countries have no vaccination recommendations specifically for pregnant women. In conclusion, there are significant differences in vaccination programs for pregnant women in Europe. Vaccination programs for pregnant women should expand in order to protect maternal and infant health. A consensus-based vaccination program is needed.     

Progress towards achieving hepatitis B control in the Cook Islands,Niue, Tokelau,and Kiribati

BackgroundHepatitis B virus (HBV) is highly endemic in many of the Pacific Island countries. Four island countries—Cook Islands, Kiribati, Niue, and Tokelau—sought to evaluate the success of their hepatitis B vaccination programs by conducting nationally representative serosurveys among children born post-vaccine introduction.MethodsCook Islands, Niue, and Tokelau conducted school-based census serosurveys because of small populations. The Cook Islands tested children in second grade; Niue tested children in early childhood education through sixth grade; and Tokelau tested children in first through sixth grades. Because Kiribati has a much larger birth cohort, it conducted a one-stage stratified serosurvey among first grade students. All four countries tested children using the Alere Determine™ rapid point of care hepatitis B surface antigen (HBsAg) test.ResultsIn the three smaller countries, no children were seropositive for HBsAg (0/245 Cook Island students, 0/183 Niuean students, 0/171 Tokelau students). In Kiribati, 39 (3.3%, 95% confidence interval 2.4–4.6%) of 1249 students were HBsAg positive. Vaccination data collected in the Cook Islands and Tokelau showed high vaccination coverage in both countries with ⩾95% birth dose coverage and 100% 3-dose coverage.ConclusionsThe Cook Islands, Niue, and Tokelau have made remarkable progress in establishing strong vaccination programs and towards decreasing the burden of hepatitis B among children. Kiribati still needs to improve vaccination coverage to achieve the <1% HBsAg target established by the World Health Organization Western Pacific Region.     

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     

World-wide control of hepatitis B

It has been 30 years since the Third World Health Assembly convened a WHO Expert Committee to consider investigation, control, and prevention of viral hepatitis. During that time, significant advances have been made in understanding the etiology and epidemiology of viral hepatitis. Technological advances of the 1970s enabled widespread rapid diagnosis and the development of vaccines of high efficacy. These advances have allowed the implementation of control programs on a global scale. Because liver cancer (PHC) is among the 10 most common cancers in the world, the link between PHC and viral hepatitis is important. Up to 80% of these cancers are attributable to the hepatitis B virus. Although the development of PHC is not associated with acute hepatitis B virus itself, the chronic HBV carrier state may be classified as a precancerous lesion. Task forces have been convened consider implementation of hepatitis control programs, especially in countries where the infection is hyperendemic. The most important prevention method is active immunization, but vaccination strategies must consider differences in geographical patterns of prevalence. In areas of low endemicity, such as North America, Western Europe, and Australia, immunization of selected high risk groups is suggested. In areas of high endemicity, such as sub-Saharan Africa, southeast Asia, and China, large-scale vaccination of infants is recommended, similar to DPT and polio vaccination programs. Current hepatitis B vaccines are favorable to mass infant immunization because of their high tolerability, excellent immunogenicity, and their ability to induce primary humeral antibody response. However, these vaccines are available in insufficient quantities and the costs are too high for use on a large scale. Newer vaccines, based on recombinant DNA techniques (rather than plasma-derived vaccines) show promise in increasing the quantity and reducing the cost of hepatitis B vaccines.     

Hepatitis B vaccination coverage among adults aged ≥ 18 years traveling to a country of high or intermediate endemicity,United States, 2015

BackgroundPersons from the United States who travel to developing countries are at substantial risk for hepatitis B virus (HBV) infection. Hepatitis B vaccine has been recommended for adults at increased risk for infection, including travelers to high or intermediate hepatitis B endemic countries.PurposeTo assess hepatitis B vaccination coverage among adults ≥ 18 years traveling to a country of high or intermediate endemicity from the United States.MethodsData from the 2015 National Health Interview Survey (NHIS) were analyzed to determine hepatitis B vaccination coverage (≥1 dose) and series completion (≥3 doses) among persons aged ≥ 18 years who reported traveling to a country of high or intermediate hepatitis B endemicity. Multivariable logistic regression and predictive marginal analyses were conducted to identify factors independently associated with hepatitis B vaccination.ResultsIn 2015, hepatitis B vaccination coverage (≥1 dose) among adults aged ≥ 18 years who reported traveling to high or intermediate hepatitis B endemic countries was 38.6%, significantly higher compared with 25.9% among non-travelers. Series completion (≥3 doses) was 31.7% and 21.2%, respectively (P < 0.05). On multivariable analysis among all respondents, travel status was significantly associated with hepatitis B vaccination coverage and series completion. Other characteristics independently associated with vaccination (≥1 dose, and ≥ 3 doses) among travelers included age, race/ethnicity, educational level, duration of U.S. residence, number of physician contacts in the past year, status of ever being tested for HIV, and healthcare personnel status.ConclusionsAlthough travel to a country of high or intermediate hepatitis B endemicity was associated with higher likelihood of hepatitis B vaccination, hepatitis B vaccination coverage was low among adult travelers to these areas. Healthcare providers should ask their patients about travel plans and recommend and offer travel related vaccinations to their patients or refer them to alternate sites for vaccination.     

The impact of a new universal infant and school-based adolescent hepatitis B vaccination program in Australia

We compared the results of two national serosurveys in Australia to evaluate the impact of universal infant vaccination and school-based programs for adolescents. Immunity improved significantly overall, especially in 1-year-olds (40.0% versus 86%; p<0.0001); in adolescents it was significantly higher in regions with established school-based programs (56.6% versus 38.8%; p=0.0008). 6.1% of 1-59-year-olds were positive for HBcAb and 0.7% for HBsAg. We have demonstrated successful implementation of universal infant hepatitis B vaccination in Australia and that school-based programs for adolescents are effective. This experience should be applicable to low prevalence countries in northern Europe which have not implemented universal hepatitis B immunisation.     

Vaccination of healthcare personnel in Europe: Update to current policies

We investigated and compared current national vaccination policies for health-care personnel (HCP) in Europe with results from our previous survey. Data from 36 European countries were collected using the same methodology as in 2011. National policies for HCP immunization were in place in all countries. There were significant differences in terms of number of vaccinations, target HCP and healthcare settings, and implementation regulations (recommended or mandatory vaccinations). Vaccination policies against hepatitis B and seasonal influenza were present in 35 countries each. Policies for vaccination of HCP against measles, mumps, rubella and varicella existed in 28, 24, 25 and 19 countries, respectively; and against tetanus, diphtheria, pertussis and poliomyelitis in 21, 20, 19, and 18 countries, respectively. Recommendations for hepatitis A immunization existed in 17 countries, and against meningococcus B, meningococcus C, meningococcus A, C, W, Y, and tuberculosis in 10, 8, 17, and 7 countries, respectively. Mandatory vaccination policies were found in 13 countries and were a pre-requisite for employment in ten. Comparing the vaccination programs of the 30 European countries that participated in the 2011 survey, we found that more countries had national vaccination policies against measles, mumps, rubella, hepatitis A, diphtheria, tetanus, poliomyelitis, pertussis, meningococcus C and/or meningococcus A, C, W, Y; and more of these implemented mandatory vaccination policies for HCP. In conclusion, European countries now have more comprehensive national vaccination programs for HCP, however there are still gaps. Given the recent large outbreaks of vaccine-preventable diseases in Europe and the occupational risk for HCP, vaccination policies need to be expanded and strengthened in several European countries. Overall, vaccination policies for HCP in Europe should be periodically re-evaluated in order to provide optimal protection against vaccine-preventable diseases and infection control within healthcare facilities for HCP and patients.     

Availability and use of hepatitis B vaccine in laboratory and nursing schools in the United States.

Hepatitis B is a well-documented occupational hazard for health care workers, including both laboratory and nursing personnel. Since the development of effective hepatitis B vaccines, the Immunization Practices Advisory Committee (ACIP) has recommended that health care workers receive the vaccine. In this study, 78 laboratory training programs and 83 nursing training programs were surveyed regarding availability and usage of hepatitis B vaccine. The hepatitis B vaccine was made available to students in 81 percent of the laboratory programs and 23 percent of the nursing programs. In those programs making the vaccine available, only 59 percent of the laboratory programs and 5 percent of the nursing programs reported a high (greater than 75 percent) use by students. Concern about cost and payment for the vaccine was the most common reason (80 percent) noted by laboratory schools that did not have hepatitis B vaccination programs for students. Of the nursing schools that did not have vaccine programs, 58 percent had not yet considered a program. At laboratory schools with vaccination programs, who paid for the vaccine (hospital or school versus student) was among the most important determinants for vaccine usage by students. These findings point out that some laboratory schools and many nursing schools have not applied the ACIP recommendations to their own programs. Educational efforts and creative payment plans for the vaccine are needed to increase the availability and use of hepatitis B vaccine among laboratory and nursing students.     

Prisoners' attitudes toward Hepatitis B vaccination

BACKGROUND: Hepatitis B continues to be a substantial problem in the United States despite the existence of a safe and effective vaccine. Vaccination programs for inmates could reach many high-risk individuals but little is known about U.S. inmates' willingness to accept hepatitis B virus (HBV) vaccination while incarcerated. The goal of this study was to assess inmates' knowledge about hepatitis B and their willingness to accept hepatitis B vaccination while incarcerated. METHODS: We interviewed 153 male and female inmates at the Rhode Island Department of Corrections (RIDOC) using a voluntary, anonymous survey. RESULTS: Ninety-three percent of inmates said they would agree to receive the hepatitis B vaccine while incarcerated. More than half of the 30% who reported having risk factors for hepatitis B did not consider themselves to be at risk for hepatitis B and almost half (44%) of all inmates were not aware that hepatitis B can be transmitted through unprotected sex. CONCLUSION: Hepatitis B vaccination programs in correctional settings are a public health priority and would be well received by the target population. Such programs would help protect the health of incarcerated persons and the communities to which they return.     

Impact of rotavirus vaccines in Sub-Saharan African countries

By the end of 2017, 32 (68%) of 47 countries in the World Health Organization’s African Region had introduced rotavirus vaccine into their national immunization programs, including 27 countries that received financial support from the Gavi, the Vaccine Alliance. Several early introducing African countries previously evaluated the impact, vaccine effectiveness, and/or cost effectiveness of their routine rotavirus vaccination programs and found that rotavirus vaccine was effective and resulted in substantial declines in hospitalizations due to rotavirus. This Special Issue of Vaccine provides additional rotavirus vaccine effectiveness and impact data from a broader range of African countries, describes the longer term impact and potential indirect benefits of rotavirus vaccination programs, describes trends in circulating genotypes in the pre- and post-vaccine introduction eras, and evaluates the cost-effectiveness of a rotavirus vaccination program in a post-introduction setting. As countries begin transitioning from Gavi support, the findings of these studies provide evidence of the impact and effectiveness of rotavirus vaccination programs under conditions of routine use.     

Acute Viral Hepatitis in the United States–Mexico Border Region: Data from the Border Infectious Disease Surveillance (BIDS) Project, 2000–2009

Little is known about the characteristics of acute viral hepatitis cases in the United States (US)–Mexico border region. We analyzed characteristics of acute viral hepatitis cases collected from the Border Infectious Disease Surveillance Project from January 2000–December 2009. Over the study period, 1,437 acute hepatitis A, 311 acute hepatitis B, and 362 acute hepatitis C cases were reported from 5 Mexico and 2 US sites. Mexican hepatitis A cases most frequently reported close personal contact with a known case, whereas, US cases most often reported cross-border travel. Injection drug use was common among Mexican and US acute hepatitis B and C cases. Cross-border travel during the incubation period was common among acute viral hepatitis cases in both countries. Assiduous adherence to vaccination and prevention guidelines in the US is needed and strategic implementation of hepatitis vaccination and prevention programs south of the border should be considered.     

Hepatitis B immunisation programmes in European Union,Norway and Iceland: Where we were in 2009?

In January 2009 25 European Union (EU) Member States (MSs), Norway and Iceland, participated in a survey seeking information on national hepatitis B vaccination programmes. Details of vaccination policy, schedule, population groups targeted for vaccination, programme funding, vaccine coverage and methods of monitoring of vaccine coverage were obtained. Twenty (74%) countries reported that they have a universal hepatitis B vaccination programme, in addition to immunisation of at risk groups; seven (26%) countries recommend HBV for high risk groups only (with some inter-country variation on groups considered at high risk). Among countries without universal hepatitis B vaccination programmes, the major factor for non-introduction is low disease endemicity.     

Effectiveness of a hepatitis A vaccination program for migrant children in Amsterdam, The Netherlands (1992-2004)

OBJECTIVE: To evaluate the impact and effectiveness of risk-group vaccination against hepatitis A targeted at migrant children living in a country with low endemicity of hepatitis A. METHODS: Retrospective population based data analysis. Routinely collected data on hepatitis A incidence in migrant children and other risk groups in Amsterdam from 1 January 1992 to 2004 were analyzed and related to exposure, immunity and vaccination coverage in migrant children. RESULTS: The overall hepatitis A incidence in Amsterdam declined after a pediatric vaccine was introduced in 1997. This decline was seen in migrant children traveling to hepatitis A-endemic countries, contacts with hepatitis A patients, primary school students, injecting drug users, and persons with unknown source of infection, but not in men who have sex with men (MSM) or in travelers to endemic countries other than migrant children. CONCLUSION: The hepatitis A vaccination campaigns are effective: they reduce both import and secondary HAV cases. The campaigns could be more efficient and cost-effective if the hepatitis B vaccinations currently given to these groups were replaced by a combined hepatitis A and B vaccine. This would increase the hepatitis A vaccination coverage considerably and further reduce the hepatitis A incidence.     

National hepatitis B vaccination closer to implementation, but not soon enough; recommendations from the Dutch Health Council

A Health Council Committee has advised the Minister of Health, Well-being and Sports not to implement universal hepatitis B vaccination in the Netherlands, as recommended by WHO and requested by members of the Dutch parliament. The Committee argued that the prevalence of hepatitis B carriers among the native Dutch population is so low (0.07%) that universal vaccination is not relevant. In contrast, vaccination was advised for children from parents who had immigrated from middle- and high-endemic countries to the Netherlands, because horizontal transmission is an important route of transmission among these people, as it is in their country of origin. This concerns an estimated 15% of the entire population. For the rest of the Dutch population the risk of horizontal transmission was considered negligible. Sexual transmission was considered more important. The optimal age of vaccination to prevent sexual transmission was considered to be shortly before puberty. The committee concludes that, as yet, no data is available to justify universal vaccination of this age group and highlights the need for additional studies, including those into the efficacy of existing preventive programs, before universal vaccination should be implemented. However, it can be argued that it is unlikely that sufficient information will be available for at least another five years, and it is certain that the risk of sexual transmission will increase during this time. Universal childhood vaccination is an investment in the youth which will pay out in the future, and which should therefore not be postponed.     

Status and progress of hepatitis B control through vaccination in the South-East Asia Region, 1992–2015

In 2016, the Immunization Technical Advisory Group of the South-East Asia Region (SEAR) endorsed a regional goal to achieve ≤1% prevalence of hepatitis B surface antigen (HBsAg) among 5-year-old children by 2020. Chronic hepatitis B virus (HBV) infection is largely preventable with a birth dose of hepatitis B vaccine (HepB-BD) followed by two to three additional doses. We reviewed the progress towards hepatitis B control through vaccination in SEAR during 1992–2015. We summarized hepatitis B vaccination data and reviewed the literature to determine the prevalence of chronic HBV infection pre- and post-vaccine introduction. We used a mathematical model to determine post-vaccine prevalence of HBsAg among 5 year olds in countries lacking national serosurvey data and estimated the impact of vaccination on disease burden. Regional coverage with three doses of hepatitis B vaccine (HepB3) increased from 56% in 2011 to 87% in 2015. By 2016, 7 of 11 countries had introduced universal HepB-BD. Regional HepB-BD coverage increased from 9% in 2011 to 34% in 2015. In 2015, estimated HBsAg among 5 year olds was 1.1% with variability among countries. Myanmar (3.8%), Timor-Leste (2.7%), Indonesia (1.8%), and India (1%) had the highest prevalence of HBsAg. During 1992–2015, vaccination prevented approximately 16 million chronic HBV infections and 2.6 million related deaths. In 2015, around 197,640 perinatal HBV infections occurred in SEAR with majority occurring in India (62%), Bangladesh (24%), and Myanmar (8%). Myanmar had the highest rate of perinatal chronic HBV infections at 16 per 1000 live births. Despite significant progress in the control of HBV, SEAR needs to secure political commitment for elimination and consider additional strategies, such as promoting health facility births, universal birth dose administration, developing strong coordination between health sectors, and using alternative vaccine delivery methods, to improve HepB-BD coverage and subsequently achieve HBV control and elimination.     

Hepatitis B vaccination for injection drug users--Pierce County, Washington, 2000

Hepatitis B vaccination has been recommended for injection drug users (IDUs) since 1982, but vaccination coverage of IDUs remains low (1), and outbreaks of hepatitis B among IDUs continue to occur. An outbreak of hepatitis B primarily among IDUs in Pierce County, Washington, detected in April 2000, included 60 cases and resulted in three deaths among IDUs co-infected with hepatitis delta virus. A program to administer hepatitis B vaccine to IDUs was implemented to control the outbreak, and the number of cases identified decreased from 13 per month in May to two cases since November. This report describes a vaccination program during which IDUs accepted hepatitis B vaccination provided free of charge in community-based settings and illustrates how effective hepatitis B vaccination programs targeted at IDUs can be implemented through collaborations between departments of health and corrections and community organizations.     

Progress towards hepatitis B prevention through vaccination in the Western Pacific, 1990–2014

Hepatitis B infections are responsible for more than 300 thousand deaths per year in the Western Pacific Region. Because of this high burden, the countries and areas of the Region established a goal of reducing hepatitis B chronic infection prevalence among children to less than 1% by 2017. This study was conducted to measure the progress in hepatitis B prevention and assess the status of achievement of the 2017 Regional hepatitis B control goal. A literature review was conducted to identify studies of hepatitis B prevalence in the countries and areas of the region, both before and after vaccine introduction. A mathematical model was applied to assess infections and deaths prevented by hepatitis B vaccination and hepatitis B prevalence in countries without recent empirical data. The majority of countries and areas (22 out of 36) were estimated to have over 8% prevalence of chronic hepatitis B infection among persons born before vaccine introduction. After introduction of hepatitis B vaccine, most countries and areas (24 out of 36) had chronic infection prevalence of less than 1% among children born after vaccine introduction. It was estimated that in the past 25 years immunization programmes in the Western Pacific Region have averted 7,167,128 deaths that would have occurred in the lifetime of children born between 1990 and 2014 if hepatitis B vaccination programmes had not been established. Regional prevalence among children born in 2012 was estimated to be 0.93%, meaning that the Regional hepatitis B control goal was achieved. While additional efforts are needed to further reduce hepatitis B transmission in the region, this study demonstrates the great success of the hepatitis B vaccination efforts in the Western Pacific Region.     

Hepatitis B vaccination programs for health care personnel in U.S. hospitals

A random sample of 232 U.S. hospitals was surveyed. Of those hospitals, 75 percent had hepatitis B vaccination programs. The presence of a program was associated with hospital size (60 percent of those with 100 beds, 75 percent with 100-499 beds, 90 percent with 500 or more beds; P = 0.0013) and hospital location (urban 86 percent; rural 57 percent; P less than 0.001). The frequency of needlestick exposures per month among hospital personnel and hospital location were directly related to and best predicted the existence of hepatitis B vaccination programs. All hospitals with programs offered vaccine to high-risk personnel (as defined by the hospital). Seventy-seven percent of hospitals paid all costs for vaccinating high-risk personnel; 19 percent paid for any employee to be vaccinated regardless of risk status. Forty-six percent of hospitals with programs were estimated to have vaccinated more than 10 percent of all eligible personnel, and 13 percent to have vaccinated more than 25 percent of eligible personnel. The highest compliance rates were associated with hospitals paying for the vaccine and requiring vaccination of high-risk personnel. Fifty-four percent of hospitals attributed noncompliance to concern regarding vaccine safety and effectiveness. The reasons why there was no vaccination program in 58 hospitals were (a) low incidence of hepatitis B virus infections among personnel, (b) cost of vaccine, and (c) vaccination being offered as part of a needlestick protocol. Full utilization of hepatitis B vaccine could eliminate the occupational hazard that hepatitis B virus presents to health care personnel.     

Combining hepatitis A and B vaccination in children and adolescents

Hepatitis A and B are common infections worldwide and their severity is related to the individual's age upon initial infection. Furthermore, when hepatitis B infection occurs in infants, the risk of becoming a chronic carrier is 90%. For hepatitis A, the lower incidence of disease arising from an improvement in living conditions leaves a greater number of children, adolescents and young adults susceptible to residual circulating virus. Consequently, initial infection occurs later in life when clinical illness is more frequent and the rate of morbidity and mortality higher. Although both viruses differ greatly, including their modes of transmission, the overlap in their epidemiology warrants the combination of hepatitis A and B vaccination. The immune response elicited by the combined hepatitis A and B vaccine following a three-dose schedule compares well with the anti-hepatitis A virus (HAV) and anti-hepatitis B sero-responses obtained with monovalent vaccines. In addition, it was shown that the seroprotection rate for anti-hepatitis B increased more rapidly with the administration of the combined vaccine, with values of more than 80% within 1 month after the first two doses (schedule, 0, 1 and 6 months). Currently, according to the World Health Organization recommendations, more than 116 countries are vaccinating their infants and/or adolescents against hepatitis B. Recently, several countries were considering or have decided to begin mass vaccination against HAV (more than fifteen states in the US, Spain (Catalonia), Italy (Puglia)). For these countries, the combination of hepatitis A and B antigens in one single vaccine offers the following advantages: fewer injections for protection against two infections, better compliance, lower implementation costs, and fewer missed vaccination opportunities. Further simplification of the schedule, by reducing the number of doses, would improve the compliance rate as well as being more convenient for the vaccinee. This should translate into a reduction in costs associated with vaccine administration. In some recent vaccine studies, the immunogenicity and safety profile of a two-dose schedule (0 and 6 months) of the adult formulation of the combined hepatitis A and B vaccine was investigated in children aged 1-11 years, as well as in adolescents aged 12-15 years. Current results indicate that this two-dose schedule of the adult formulation could be considered a viable alternative for immunization of children and adolescents.