Hepatitis A virus seroprevalence by age and world region, 1990 and 2005

Objective

To estimate current age-specific rates of immunity to hepatitis A virus (HAV) in world regions by conducting a systematic review and meta-analysis of published data. The estimation of the global burden of hepatitis A and policies for public health control are dependent on an understanding of the changing epidemiology of this viral infection.

Methods

Age-specific IgG anti-HAV seroprevalence data from more than 500 published articles were pooled and used to fit estimated age-seroprevalence curves in 1990 and 2005 for each of 21 world regions (as defined by the Global Burden of Disease 2010 Study).

Findings

High-income regions (Western Europe, Australia, New Zealand, Canada, the United States, Japan, the Republic of Korea, and Singapore) have very low HAV endemicity levels and a high proportion of susceptible adults, low-income regions (sub-Saharan Africa and parts of South Asia) have high endemicity levels and almost no susceptible adolescents and adults, and most middle-income regions have a mix of intermediate and low endemicity levels.

Conclusion

Anti-HAV prevalence estimates in this analysis suggest that middle-income regions in Asia, Latin America, Eastern Europe, and the Middle East currently have an intermediate or low level of endemicity. The countries in these regions may have an increasing burden of disease from hepatitis A, and may benefit from new or expanded vaccination programs.     

Waning of anti-HAV immunity in Shijiazhuang prefecture,Hebei province,China: A comparison of seroprevalence between 1992 and 2011

Objective

To study the epidemiological patterns of hepatitis A, and immunity of entire population in Shijiazhuang prefecture, Hebei province, a former hyper-endemic area in north China.

Methods

Cross-sectional, seroprevalence surveys with two-stage cluster sampling were conducted among population older than 2-year between 1992 and 2011. During the 2011 serological survey, blood samples from infants <18 months without hepatitis A immunization history were also collected to determine maternal anti-HAV antibody. Serum samples were tested for anti-HAV antibody by domestic reagent or Abbott reagent. Viral hepatitis incidence rates and gross domestic product data were derived from local governmental statistics.

Results

Concomitant with the reduction of reported hepatitis A cases between 1992 and 1996 was a significant decline of HAV infections. The average prevalence decreased from 93.6% to 41.9%, and the average age at new infection was postponed from infancy to adolescence. This was attributed to improved socio-economic conditions. With intensive vaccination, a return of new seroconversion rate and seroprevalence was observed. A well fitted exponential regression equation (R² = 0.96, p < 0.0001) modeled that the maternal antibody would wane to <20 mIU/mL at 13 months.

Conclusion

Benefiting from the booming economy, rapid improvement in sanitation, safe water supply, and implementation of hepatitis A vaccines, the epidemiological pattern of hepatitis A moved from high to intermediate endemicity in Shijiazhuang. Policy makers should be aware of the waning of immunity in entire population, and adapt immunization strategy timely, to ensure a lifelong protection against hepatitis A virus.     

Cost-effectiveness analysis of universal childhood hepatitis A vaccination in Brazil: Regional analyses according to the endemic context

Objective

To conduct a cost-effectiveness analysis of a universal childhood hepatitis A vaccination program in Brazil.

Methods

An age and time-dependent dynamic model was developed to estimate the incidence of hepatitis A for 24 years. The analysis was run separately according to the pattern of regional endemicity, one for South + Southeast (low endemicity) and one for the North + Northeast + Midwest (intermediate endemicity). The decision analysis model compared universal childhood vaccination with current program of vaccinating high risk individuals. Epidemiologic and cost estimates were based on data from a nationwide seroprevalence survey of viral hepatitis, primary data collection, National Health Information Systems and literature. The analysis was conducted from both the health system and societal perspectives. Costs are expressed in 2008 Brazilian currency (Real).

Results

A universal immunization program would have a significant impact on disease epidemiology in all regions, resulting in 64% reduction in the number of cases of icteric hepatitis, 59% reduction in deaths for the disease and a 62% decrease of life years lost, in a national perspective. With a vaccine price of R$16.89 (US$7.23) per dose, vaccination against hepatitis A was a cost-saving strategy in the low and intermediate endemicity regions and in Brazil as a whole from both health system and society perspective. Results were most sensitive to the frequency of icteric hepatitis, ambulatory care and vaccine costs.

Conclusions

Universal childhood vaccination program against hepatitis A could be a cost-saving strategy in all regions of Brazil. These results are useful for the Brazilian government for vaccine related decisions and for monitoring population impact if the vaccine is included in the National Immunization Program.     

A nationwide survey of past hepatitis A infections among Canadian adults

Background

Hepatitis A virus (HAV) infection rates in Canada are low and declining. A nationwide pediatric serosurvey in 2003 confirmed that HAV infection is uncommon in children. Additional seroepidemiological data for adults would help to guide domestic use of HAV vaccines.

Methods

A country-wide survey of HAV antibody positivity and selected risk factors was conducted among 18–69 year olds identified by random digit dialing, in samples proportional to regional populations. Volunteers were sent study materials and returned oral fluid and completed questionnaires by mail. An ultra-sensitive assay was used to detect HAV antibody in oral fluid. Multiple logistic regression was used for risk factor assessment.

Results

Of 2104 potential study participants, 1552 (74%) returned an adequate oral fluid specimen and questionnaire. Anti-HAV was detected in 509 individuals (33%) and was associated with birth in HAV endemic areas, self-reported hepatitis A vaccination, prior travel to endemic areas, and increasing age. Only 15% reported having been vaccinated. Among Canadian-born, non-vaccinated participants anti-HAV was present in 20%, ranging regionally from 14% to 30%. Age-specific positivity rates in this subset were: 18–29 years 2.6%; 30–39 years 6.1%; 40–49 years 11.4%; 50–59 years 26.4% and 60–69 years 45.9%. Travel to HAV-endemic countries was reported by 55% of participants but only 24% of travelers had been vaccinated.

Conclusions

Past HAV infection rates among Canadian-born, non-vaccinated individuals are low in young adults and increase by two-fold per age decade. Travel to endemic areas is a significant risk factor, amenable to prevention by greater use of HAV vaccine.     

Hepatitis A vaccination coverage among adults 18–49 years traveling to a country of high or intermediate endemicity,United States

Background

Since 1996, hepatitis A vaccine (HepA) has been recommended for adults at increased risk for infection including travelers to high or intermediate hepatitis A endemic countries. In 2009, travel outside the United States and Canada was the most common exposure nationally reported for persons with hepatitis A virus (HAV) infection.

Objective

To assess HepA vaccination coverage among adults 18–49 years traveling to a country of high or intermediate endemicity in the United States.

Methods

We analyzed data from the 2010 National Health Interview Survey (NHIS), to determine self-reported HepA vaccination coverage (≥1 dose) and series completion (≥2 dose) among persons 18–49 years who traveled, since 1995, to a country of high or intermediate HAV endemicity. Multivariable logistic regression and predictive marginal analyses were conducted to identify factors independently associated with HepA vaccine receipt.

Results

In 2010, approximately 36.6% of adults 18–49 years reported traveling to high or intermediate hepatitis A endemic countries; among this group unadjusted HepA vaccination coverage was 26.6% compared to 12.7% among non-travelers (P-values < 0.001) and series completion were 16.9% and 7.6%, respectively (P-values < 0.001). On multivariable analysis among all respondents, travel status was an independent predictor of HepA coverage and series completion (both P-values < 0.001). Among travelers, HepA coverage and series completion (≥2 doses) were higher for travelers 18–25 years (prevalence ratios 2.3, 2.8, respectively, P-values < 0.001) and for travelers 26–39 years (prevalence ratios 1.5, 1.5, respectively, P-value < 0.001, P-value = 0.002, respectively) compared to travelers 40–49 years. Other characteristics independently associated with a higher likelihood of HepA receipt among travelers included Asian race/ethnicity, male sex, never having been married, having a high school or higher education, living in the western United States, having greater number of physician contacts or receipt of influenza vaccination in the previous year. HepB vaccination was excluded from the model because of the significant correlation between receipt of HepA vaccination and HepB vaccination could distort the model.

Conclusions

Although travel to a country of high or intermediate hepatitis A endemicity was associated with higher likelihood of HepA vaccination in 2010 among adults 18–49 years, self-reported HepA vaccination coverage was low among adult travelers to these areas. Healthcare providers should ask their patients’ upcoming travel plans and recommend and offer travel related vaccinations to their patients.     

Field effectiveness of hepatitis A vaccine and uptake of post exposure prophylaxis following a change to the Australian guidelines

Background

In 2009, national guidelines for hepatitis A control in Australia changed to recommend hepatitis A vaccine (HAV), instead of normal human immune globulin (NHIG), for post-exposure prophylaxis (PEP).

Aims

(1) Determine whether the uptake of PEP among contacts of hepatitis A cases changed after the introduction of the new guidelines, and (2) assess the field effectiveness of the HAV used as PEP in preventing infection among contacts of hepatitis A cases.

Methods

A retrospective cohort of contacts from hepatitis A cases reported to metropolitan Public Health Units in Sydney, Australia, between October 2008 and June 2010, was identified. Contacts were analysed by time period, age, PEP type, and susceptibility to hepatitis A. The relative risk (RR) of hepatitis A infection among susceptible contacts who received HAV, compared with susceptible contacts who had not received HAV, was calculated to estimate the effectiveness of the HAV when used as PEP.

Results

The uptake of PEP by susceptible contacts increased from 76% (n = 133) to 89% (n = 127) after the introduction of the new guidelines. Before the change in guidelines, no one who received PEP was later reported with hepatitis A. After the change in guidelines, one of the 123 contacts who received HAV as PEP was subsequently reported with hepatitis A. However, this case was likely to have been co-exposed with a primary case. Conservatively, assuming this was a secondary case, the vaccine effectiveness of HAV was 95.6% (66.1%–99.4%). Nine of 10 incident cases of hepatitis A were contacts who did not receive any PEP.

Conclusion

The improved uptake of PEP and the high estimate of the effectiveness of HAV provides support for using HAV for PEP. The very high occurrence of hepatitis A among contacts who did not receive any PEP further highlights the importance of PEP in preventing hepatitis A infection.     

Cost-effectiveness analysis of behavioral interventions to improve vaccination compliance in homeless adults

Aims

To estimate the cost-effectiveness of three behavioral interventions provided to enhance hepatitis A virus (HAV) and hepatitis B virus (HBV) joint vaccination (HAV/HBV) compliance among homeless persons living in Los Angeles County.

Scope

A cost-effectiveness analysis (CEA) based on data from a randomized trial where the costs and compliance data from the trial are incorporated into two Markov models, simulating the natural history of acute and chronic hepatitis infection, following HAV/HBV vaccination.

Conclusions

Reductions in HBV-related disease is cost-effective to society and is associated with substantial improvements in quality of life.     

Vaccination coverage against hepatitis A and B viruses, Streptococcus pneumoniae, seasonal flu,and A(H1N1)2009 pandemic influenza in HIV-infected patients

Background

Several vaccines are recommended in HIV-infected patients due to an increased risk of vaccine-preventable infections, severe forms of the disease, or shared transmission routes. Few data are available regarding vaccination coverage and its determinants in this population.

Methods

A cross-sectional study was performed in HIV-infected patients included in a hospital-based cohort in 2011. Vaccination coverage against hepatitis A virus (HAV), hepatitis B virus (HBV), seasonal and A(H1N1)2009 pandemic influenza, and invasive pneumococcal diseases (IPD) were recorded. Factors associated with vaccination were assessed by multivariate logistic regression.

Results

2467 patients were included (median age: 47 years; male gender 71.5%; men having sex with men (MSM): 43.9%; CDC stage C: 24.3%; HBV and/or hepatitis C virus co-infection: 14.4%). Median duration of HIV infection was 10 years and 93.1% of patients received combination antiretroviral therapy. At baseline, the median CD4 count was 527 cells/mm³ and HIV viral load was <50 copies/mL in 83.3% of cases. Vaccination coverage for HBV, HAV, seasonal influenza, A(H1N1)2009 pandemic influenza, and IPD were 61.9%, 47.4%, 30.9, 48.3%, and 64.6%, respectively. Factors independently associated with vaccination were a younger (HBV) or an older age (influenza), male gender (HBV, HAV), MSM (HBV), CD4 count >200/mm³ and HIV-RNA <50 copies/mL (IPD, influenza), longer duration of HIV infection (IPD, influenza), and follow-up by an experienced physician (HBV, IPD).

Conclusions

Vaccination coverage remained insufficient for all vaccine-preventable infections investigated in this study. Determinants for vaccination were largely not evidence-based, and efforts should be focused on improving physicians’ knowledge about guidelines.     

Evidence-to-policy gap on hepatitis A vaccine adoption in 6 countries: Literature vs. policymakers’ beliefs

Background

National vaccine adoption decisions may be better understood by linking multiple data sources. When examining countries’ decisions to adopt the hepatitis A vaccine, applying multiple research methods can facilitate assessments of gaps between evidence and policy. We conducted a literature review on hepatitis A and stakeholder interviews about decisions to adopt the vaccine in six countries (Chile, India, South Korea, Mexico, Russia, and Taiwan).

Methods

A systematic literature review was conducted across five literature databases. The review identified and abstracted 340 articles, supplemented by internet search. In addition, we interviewed 62 experts and opinion leaders on hepatitis A and/or vaccines. Data from the two sources were analyzed to identify gaps around epidemiologic data, economic data, and barriers/facilitators of hepatitis A vaccine adoption.

Results

Epidemiologic data gaps were found in Chile and Russia, where stakeholders believed data to be more solid than the literature documented. Economic data on hepatitis A was found to be weak across all countries despite stakeholders’ agreement on its importance. Barriers and facilitators of vaccine adoption such as political will, prioritization among vaccines, and global or local recommendations were discussed more by stakeholders than the literature. Stakeholders in India and Mexico were not concerned with the lack of data, despite growing recognition in the literature of the epidemiological transition and threat of outbreaks.

Conclusions

Triangulation of results from two methods captured a richer story behind vaccine adoption decisions for hepatitis A. The discrepancy between policymakers’ beliefs and existing data suggest a decline in priority of hepatitis A or weak investment in data collection. Filling the confirmed data gaps in seroprevalence or economic data is important to help guide policy decisions. Greater communication of the risk of hepatitis A and the benefits of the vaccine may help countries undergoing the epidemiologic transition.     

Hepatitis A and travel amongst Nova Scotia postsecondary students: evidence for a targeted vs. universal immunization strategy

Background

Canadian guidelines recommend hepatitis A virus (HAV) vaccination for high-risk persons, such as travelers to HAV-endemic areas. The US CDC advocates universal immunization.

Objectives

To explore whether a universal strategy for HAV immunization rather than the Canadian targeted approach for travelers is justified by measuring compliance of postsecondary students with Canadian guidelines.

Methods

A cross-sectional study using an electronic survey method elicited HAV risk factors, immunization history, disease status, and factors affecting immunization status from postsecondary students. Seropositivity was determined by measuring HAV antibodies in saliva from a convenience sample of survey participants within each study group. Statistical analysis used Fisher's exact test and logistic regression.

Results

We received 2279 completed surveys (10.6% response) and 235 saliva samples (58.7% response). A total of 1380 (60.6%) participants had traveled to HAV-endemic regions and 1851 (81.2%) were planning to do so within the next 5 years. Less than half who traveled to HAV-endemic areas reported a history of HAV vaccination (48.0%). HAV seropositivity rates were higher amongst those who traveled to (63.6%) or were planning to travel to (55.0%) HAV-endemic areas than those who had never traveled or had no plans to travel to such areas (17.4%). Only 8.9% of unvaccinated students were seropositive (5.3% of Canadian-born students). Amongst unvaccinated, seropositive students, there was a nonsignificant trend for higher seropositivity in those who had previously traveled to HAV-endemic areas (14.7%) than those who had not traveled abroad (4.4%), suggesting an exposure to HAV during travel. Nearly all (96.5%) unvaccinated students, who were willing to be vaccinated based on current knowledge or if their doctor recommended it, indicated a willingness to receive vaccine if it were provided free of charge.

Conclusions

Current Canadian guidelines for HAV vaccination are not being followed within the postsecondary student population. Given high rates of travel to HAV-endemic areas in this population, a universal approach to HAV vaccination may be warranted.     

Prevalencia de anticuerpos frente al virus de la hepatitis A en trabajadores del ámbito sanitario y variables asociadas

Objective

Vaccination against hepatitis A is recommended in risk groups, including healthcare workers. The objective of this study was to determine the prevalence of antibodies to HAV (IgG) among workers in the healthcare setting in order to establish criteria for vaccination.

Methods

A cross-sectional, analytic, observational study of 4,864 employees was undertaken in four healthcare companies in Catalonia (Spain). The variables gathered included personal data, professional category, location of employment, and serology.

Results

The overall prevalence of antibodies to HAV was 52.7%. The prevalence significantly increased with greater age. The mean age of seropositive workers was 41.5 years compared with 34.3 in workers with negative serology. The highest prevalence of antibodies was found in cleaning employees (74.2%) and catering staff (75.3%).

Discussion

Given the high prevalence of seronegative adults susceptible to infection and the characteristics of their professional activities, vaccination of all staff working in health institutions should be considered.     

Global epidemiology of hepatitis B virus infection: new estimates of age-specific HBsAg seroprevalence and endemicity

Objective

Chronic hepatitis B virus infection is one of the most serious infections and a major risk factor for deaths from cirrhosis and liver cancer. We estimate age-, sex- and region-specific prevalence of chronic HBV infection and calculate the absolute number of persons being chronically infected.

Methods

A systematic review of the literature for studies reporting HBV infection was conducted and worldwide HBsAg seroprevalence data was collected over a 27-year period (1980–2007). Based on observed data, age-specific prevalence and endemicity were estimated on a global level and for all world regions for 1990 and 2005 using an empirical Bayesian hierarchical model.

Findings

From 1990 to 2005, the prevalence of chronic HBV infection decreased in most regions. This was particularly evident in Central sub-Saharan Africa, Tropical and Central Latin America, South East Asia and Central Europe. Despite this decrease in prevalence, the absolute number of HBsAg positive persons increased from 223 million in 1990 to 240 million in 2005. Age-specific prevalence varied by geographical region with highest endemicity levels in sub-Saharan Africa and prevalence below 2% in regions such as Tropical and Central Latin America, North America and Western Europe. Asian regions showed distinct prevalence patterns with lower intermediate prevalence in South Asia, but up to 8.6% HBsAg prevalence in East Asia. Strong declines were seen in South East Asian children.

Conclusion

Declines in HBV infection prevalence may be related to expanded immunization. The increasing overall number of individuals being chronically infected with HBV, and the widespread global differences in HBV prevalence call for targeted approaches to tackle HBV-related mortality and morbidity. HBV infection prevalence data are needed at country and sub-national level to estimate disease burden and guide health and vaccine policy.     

Declining incidence of hepatitis A in Amsterdam (The Netherlands), 1996–2011: Second generation migrants still an important risk group for virus importation

Background

The Netherlands is a very low endemic country for hepatitis A virus infections (HAV, notification rate of <1/100,000). Historically in Amsterdam, a large proportion of infections are imported from Turkey and Morocco in children returning from summer holiday. Annually since 1998, the public health service of Amsterdam has targeted these children for HAV vaccination before the summer. As the population of non-western immigrants and their descendents increases, we describe recent trends in HAV in ethnic groups in Amsterdam (1996–2011), identifying current risk groups and recommending targeted prevention through vaccination.

Methods

We studied all cases of (non-homosexually acquired) HAV infection notified in the Amsterdam region (1996–2011, n = 819) by ethnic group and generation (first/second generation migrants: FGM and SGM respectively). Incidence rates were estimated as the average number of cases per 100,000/year. Using Poisson regression, we calculated incidence rate ratios (IRR) by ethnic group and generation adjusted for age and calendar year, and modeled seasonal variation using a smoothed time series.

Results

Incidence of HAV in Amsterdam dropped from 24.8/100,000 population in 1996 (178 cases) to 1.0/100,000 in 2011 (8 cases). Since 2005, 56% of cases are imported, the majority (62%) in second generation migrant (SGM) children of Moroccan, or other non-western ethnic backgrounds. The adjusted IRR in SGM relative to the ethnic Dutch population was 3.7 (95% CI: 2.3–6.1) in Moroccan SGM, 4.3 (95%CI: 2.6–7.2) in SGM of other non-western backgrounds and 1.9 (95%CI: 0.8–4.1) in Turkish SGM.

Conclusion

Though incidence of HAV in Amsterdam has declined substantially since 1996, it is still higher in SGM children of Moroccan & other non-western ethnic backgrounds. In line with WHO recommendations of June 2012, introduction of single-dose HAV vaccination, targeted at SGM children from HAV endemic countries, could be considered within the routine childhood vaccination schedule.     

Kinetics of maternally acquired anti-hepatitis A antibodies: Prediction of waning based on maternal or cord blood antibody levels

Background

Timing is critical for efficient hepatitis A vaccination in high endemic areas as high levels of maternal IgG antibodies against the hepatitis A virus (HAV) present in the first year of life may impede the vaccine response.

Objectives

To describe the kinetics of the decline of anti-HAV maternal antibodies, and to estimate the time of complete loss of maternal antibodies in infants in León, Nicaragua, a region in which almost all mothers are anti-HAV seropositive.

Methods

We collected cord blood samples from 99 healthy newborns together with 49 corresponding maternal blood samples, as well as further blood samples at 2 and 7 months of age. Anti-HAV IgG antibody levels were measured by enzyme immunoassay (EIA). We predicted the time when antibodies would fall below 10 mIU/ml, the presumed lowest level of seroprotection.

Results

Seroprevalence was 100% at birth (GMC 8392 mIU/ml); maternal and cord blood antibody concentrations were similar. The maternal antibody levels of the infants decreased exponentially with age and the half-life of the maternal antibody was estimated to be 40 days. The relationship between the antibody concentration at birth and time until full waning was described as: critical age (months) = 3.355 + 1.969 × log₁₀(Ab-level at birth). The survival model estimated that loss of passive immunity will have occurred in 95% of infants by the age of 13.2 months.

Conclusions

Complete waning of maternal anti-HAV antibodies may take until early in the second year of life. The here-derived formula relating maternal or cord blood antibody concentrations to the age at which passive immunity is lost may be used to determine the optimal age of childhood HAV vaccination.     

Factors associated with the immune response to hepatitis A vaccination in HIV-infected patients in the era of highly active antiretroviral therapy

Introduction

HIV seropositivity is considered a risk factor for complications in hepatitis A virus (HAV) infection. HAV vaccination schedules are widely implemented in HIV-infected patients, but the immune response remains impaired.

Methods

We analysed the response to vaccination (antiHAV titres ≥20 IU/l) in 282 HIV-infected patients included in a standard (1440 Elisa Units (EU) at 0, 6 months) or rapidly accelerated schedule (720 EU at 0, 7, 21 days and 6 months) between 1997 and 2009. Factors associated with the response to vaccination were analysed using logistic regression.

Results

The overall response rate was 73.4%. Male sex (OR: 0.16, 95% CI 0.05–0.51) and hepatitis C virus co-infection (OR: 0.30, 95% CI 0.14–0.74) were associated with a lower probability of response. Protective antibody response was associated with a higher CD4/CD8 ratio (OR: 3.69, 95% CI 1.3–10.5) and having received two doses of standard schedule (compared with patients receiving only one dose of the same schedule) (OR: 2.51, 95% CI 1.22–5.15). Three doses of the rapidly accelerated schedule were not more effective than a single dose of 1440 EU (OR: 1.32, 95% CI 0.48–3.63).

Conclusion

The low responses observed in patients receiving a single dose suggest the need to emphasize adhesion to vaccination protocols to avoid failure. The CD4/CD8 ratio may be considered as an immune status marker which could help to better choose the moment of vaccination. Our findings underscore the importance of identifying strategies that optimize the timing and effectiveness of hepatitis A vaccination in HIV-infected patients and of the need for further studies on individual factors such as sex and hepatitis C co-infection that may affect the response to vaccination. Likewise, the sub-optimal effectiveness of three doses of 720 EU in the rapidly accelerated schedule, if confirmed in future studies, might lead to a revision of the current schedule recommended for HIV-infected travellers.     

Seroprevalence of viral hepatitis A in the Czech Republic

Over recent decades, the epidemiology of hepatitis A has changed in most European countries: the age of infection has been shifting towards older age groups. In view of this evolution and the central location of the Czech Republic in Europe, we wanted to assess current anti-hepatitis A seroprevalence. We determined the anti-hepatitis A seroprevalence among three different groups: military personnel between 1991–1995, prior to their deployment as UN troops, civilians participating in a national serological survey in 1996 and volunteers for vaccine clinical trials in 1996. The anti-HAV prevalence <20 years of age was about 4%; in the age cohort 40–49 it ranged between 47 and 51%. Only over the age of 60 years was the seroprevalence rate >85%. The risk of acquiring HAV is low for younger age groups. We could demonstrate some regional differences with higher rates in some age strata for the North Bohemian region and the lowest rates in East Bohemia and Prague. Compared to archived sera from a previous serological survey in 1984 we demonstrate a shift towards low endemicity. For the first time it is shown that an Eastern European country, i.e. the Czech Republic, is a country with a low endemicity for HAV. Substantial parts of the population are or will be at an increased risk of HAV infection and active immunisation against HAV should be considered.     

Seroepidemiology of Hepatitis A in South Korea: A Nationwide Study by the Eone Reference Laboratory

Background

We evaluated the recent prevalence of serologic markers of hepatitis A virus (HAV) in South Korea.

Methods

The study data were the results of 60 126 anti-HAV (total) tests and 30 786 anti-HAV IgM tests that were performed during April 2009 through March 2010 by the Eone Reference Laboratory at the request of 1935 institutions throughout Korea.

Results

The overall positivity rate was 51.06% on the anti-HAV (total) test and 11.20% on the anti-HAV IgM test. As compared with the other age groups the rate of anti-HAV (total) positivity was significantly lower (P < 0.001), and the rate of anti-HAV IgM positivity was significantly higher (P < 0.001), among Koreans aged 11 to 40 years. The seroprevalence of anti-HAV IgM significantly differed according to region but not by referral date.

Conclusions

This was the largest nationwide study in South Korea by 1 laboratory, and it provides useful recent baseline data on hepatitis A in Asia. The findings suggest that active immunization of younger Koreans should be made a priority.Key words: hepatitis A virus, South Korea, immunization     

Seroprevalence of hepatitis A virus antibodies in the U.S.: results from the National Health and Nutrition Examination Survey

Objectives

We described seroprevalence of antibody to hepatitis A virus (anti-HAV) in the United States during 1999–2006 and compared it with seroprevalence before the availability of vaccine.

Methods

We analyzed data from the 1988–1994 and 1999–2006 National Health and Nutrition Examination Survey (NHANES) to obtain estimates of anti-HAV seroprevalence for the U.S. household population. We grouped region of residence based on the 1999 Advisory Committee on Immunization Practices recommendations into 17 states with any recommendation (vaccinating) and 33 states without any recommendation (non-vaccinating).

Results

During 1999–2006, the overall seroprevalence of anti-HAV was 34.9% (95% confidence interval [CI] 33.1, 36.7). During 1999–2006, U.S.-born children living in vaccinating states (33.8%, 95% CI 26.2, 42.2) had a higher seroprevalence than children in non-vaccinating states (11.0%, 95% CI 9.4, 12.8; p<0.001). Seroprevalence among children increased from 8.0% (95% CI 6.3, 10.1) during 1988–1994 to 20.2% (95% CI 16.0, 24.8) during 1999–2006 (p<0.001). For U.S.-born children aged 6–19 years, the strongest factor associated with seroprevalence was residence in vaccinating states. Among U.S.-born adults aged >19 years, the overall age-adjusted seroprevalence of anti-HAV was 29.9% (95% CI 28.3, 31.5) during 1999–2006, which was not significantly different from the seroprevalence during 1988–1994 (32.2%, 95% CI 30.1, 34.4).

Conclusions

Increases in seroprevalence among children in vaccinating states suggest a positive effect of the 1999 vaccination recommendations.Hepatitis A vaccines were licensed in the United States in 1995. Shortly thereafter, the Advisory Committee on Immunization Practices (ACIP) made recommendations for routine vaccination of children aged 2–18 years living in communities with the highest rates of infection and disease.¹ By 1999, epidemiologic evidence suggested that the strategy had a limited impact on national disease incidence;² thus, in 1999, ACIP recommended routine vaccination for children living in 11 mostly western states, with mean incidence rates that were at least twice the 1987–1997 national mean (i.e., ≥20 cases per 100,000 population). In an additional six states, where mean incidence rates were higher than the national average, but less than twice that value (i.e., 10–19 cases per 100,000 population), ACIP recommended consideration of routine vaccination of children.² The impact of this expansion was dramatic: by 2003, acute hepatitis A disease had declined overall by 76%, from a rate of 10.7 per 100,000 population during 1990–1997 to 2.6 per 100,000 population in 2003.³ In 2007, the rate was the lowest ever reported (1.0 per 100,000 population).⁴ In 2006, ACIP recommended integration of hepatitis A virus (HAV) vaccine into the routine childhood vaccination schedule, with HAV vaccine administered for all children at age 12 months.⁵Population-based seroprevalence surveys play a critical role in supplementing data systems for disease incidence, vaccination coverage, and vaccine adverse events in the development of vaccination policy.⁶ Before the availability of vaccine, seroprevalence of antibody to HAV (anti-HAV) in the population solely reflected prior infection.⁷ Currently, seroprevalence can reflect immunity due to either previous infection or to vaccination. Our objectives were to describe patterns in the seroprevalence of anti-HAV in the U.S., evaluate sociodemographic factors associated with seroprevalence during 1999–-2006, and compare these findings with seroprevalence patterns before the availability of vaccine.     

Hepatitis A shifting epidemiology in the Middle East and Africa

Data on the endemicity of hepatitis A virus (HAV) infection in Africa and the Middle East are scant, but most of Africa appears to remain a high endemicity region, with the exception of subpopulations in some areas, e.g. White people in South Africa. Saudi Arabia is a model for the Middle East, and is a country in which shifting HAV epidemiology has been documented in recent years, concurrent with the social and economic development that has occurred over the last two decades. Earlier studies generally showed very high prevalence rates, with most people becoming infected in early childhood. Between 1989 and 1995, however, there was a significant fall in the seroprevalence of antibodies to HAV in children up to 12 years old throughout the country except in one region bordering the Yemen. The highest seroprevalence is found in children from rural backgrounds, while the seroprevalences in Bedouin and urban children are similar. Seroprevalence is related to socioeconomic status, being highest in the lowest groups. Similar findings have been reported from other countries in the Middle East. The existence of pockets of high endemicity for HAV infection with surrounding areas shifting towards intermediate endemicity may lead to outbreaks, and widespread vaccination should be considered.