Age Group-Specific Assessment of Changing Seroepidemiology of Hepatitis A Virus Infection in North India.

Introduction Routine immunization against hepatitis A virus (HAV) infection has not been warranted in India, but an epidemiological shift from hyperendemicity to intermediate endemicity has been detected in recent years. The present study was planned to gather the age group-specific seroprevalence data of hepatitis A IgG antibodies in various age groups and evaluate any early trends of seroepidemiological shift. Method This was a hospital-based cross-sectional study. The detection of IgG antibodies for hepatitis A was done using an HAV Ab kit (Dia.Pro, Milan, Italy) in sera of individuals from >1 to 80 years of age and consenting to participate. Data on sociodemographic factors and potentially predisposing factors of HAV was collected on a predesigned questionnaire. At the time of final analysis, patients were divided into three groups children one to <18 years, adults ≥18 to <60 years, and old ≥60 to 80 years for comparative analysis. Result A total of 1,250 patients were included in the final analysis (129 children, 928 adults, and 193 old). The male/female ratio of the study participants was 1.4:1. The majority (85%) of them came from rural and semi-urban areas. They generally had lower socioeconomic status (SES) with poor literacy rates. Most of the enrolled cases (n=800/1,250, 64%) reported the use of groundwater, and 58.7% (n=734/1,250) consume water without any purification. Of the study participants, 90.8% reported the use of toilets for defecation, and 96.7% of the cases use soap for handwashing after defecation. The majority of adult (90%) and old age (99%) participants were seropositive for anti-HAV IgG antibodies as compared to children (80%). No significant differences were observed in the seropositivity rates and the SES class of the study participants. Conclusion About 20% of children did not have anti-HAV IgG antibodies in the present study, indicating that they are not exposed to HAV. This could be because of their better living conditions such as the availability of safe drinking water and improved sanitation and hygiene. We support the current guidelines of the Indian Academy of Pediatrics (IAP), which recommends immunization for hepatitis A vaccination at 12 months of age. Adult vaccination is not needed in North India.

Novel flavonoid hybrids as potent antiviral agents against hepatitis A: Design, synthesis and biological evaluation.

Two series of flavonoid hybrids, totaling 42 compounds, were designed, synthesized and evaluated to develop antiviral compounds effective against hepatitis A virus (HAV). A recombinant viral screening system revealed that most of the synthesized derivatives exhibited significant anti-HAV activity, and compounds B2, B3, B5 and B27 were identified as potential inhibitors of HAV. Post-treatment of cells with B2, B3, B5 and B27 after HAV infection strongly suppressed HAV infection, whereas pretreatment or simultaneous treatment were ineffective. Furthermore, these four compounds significantly inhibited HAV (HM175/18f strain) production in a dose-dependent manner. Analyses using HAV subgenomic replicon systems indicated that these compounds specifically inhibit HAV RNA replication. More importantly, the most potent compounds B2 and B27 also showed clear inhibitory effects on two other HAV strains, KRM031 and TKM005, which also isolated from clinical patients. Our study is the first to report these newly designed flavonoid hybrids as lead compounds for the development of novel anti-HAV drugs.

Accuracy assessment of total or IgG Immunoglobulin to hepatitis A virus tests around immunity threshold.

BACKGROUND: Anti-hepatitis A virus (HAV) antibody titers at 20 IU/L are assumed to correlate with protection against HAV challenge. METHODS: We examined the accuracy and precision of currently in use immunoassays for total or anti-HAV IgG determination, by repeated testing of dilutions of the international anti-HAV standard, within a 10-50 IU/mL concentration range. RESULTS AND CONCLUSION: Eight immunoassays were evaluated. All could confidently identify people who need to be vaccinated, or who might benefit from a booster vaccine: no positive interpretation for the 10 and 15 IU/mL concentrations. However, qualitative interpretation may differ from test to test in the 15-30 IU/mL range. This variation has to be taken into account when comparing seroprevalence data.

Cell Culture Systems and Drug Targets for Hepatitis A Virus Infection.

Hepatitis A virus (HAV) infection is one of the major causes of acute hepatitis, and this infection occasionally causes acute liver failure. HAV infection is associated with HAV-contaminated food and water as well as sexual transmission among men who have sex with men. Although an HAV vaccine has been developed, outbreaks of hepatitis A and life-threatening severe HAV infections are still observed worldwide. Therefore, an improved HAV vaccine and anti-HAV drugs for severe hepatitis A should be developed. Here, we reviewed cell culture systems for HAV infection, and other issues. This review may help with improving the HAV vaccine and developing anti-HAV drugs.

Architect i2000 SR has improved turnaround time for infectious disease serology testing over Vitros ECiQ.

BACKGROUND: Vitros ECiQ and Architect i2000 SR are two automated instruments used to detect serology biomarkers of hepatitis A, B and C viruses, and HIV infections. We compared performance of the Architect to the Vitro EciQ after implementation at our institution. METHODS: A retrospective review was performed to compare patient samples tested on the Vitros ECiQ or Architect for hepatitis and HIV serological assays. The positivity rate, frequency of equivocal results, turnaround times (TAT), and hands-on time (HOT) were analyzed. RESULTS: There was no statistical difference in the positivity rate between the two instruments, with the exception of two assays. An increase in equivocal results was observed for the Architect (0.2% vs 0.5%). Notably, the TAT for the Architect i2000 was shorter for all except one assay (31.6 vs 33.7 hours) and demonstrated improved workflow. CONCLUSIONS: Overall, both instruments performed comparably. Architect had shorter TAT over Vitros.

RNA testing for the diagnosis of acute hepatitis A during the 2017 outbreak in France.

Diagnostic of acute hepatitis A virus (HAV) infection is based on the detection of anti-HAV IgM without testing for the pathogen itself. We evaluated the usefulness of HAV RNA testing for confirmation of acute hepatitis A and to provide indications about the level of HAV replication in HIV-positive and HIV-negative subjects during an unprecedented outbreak of HAV observed in France in 2017. HAV RNA was detected in 38 out of 41 (92.6%) subjects with a clinical diagnosis of acute hepatitis A, whereas nine cases tested positive for anti-HAV IgM in whom the diagnosis of acute hepatitis A was not retained were found negative for HAV RNA. All subjects in the control group were also tested negative for HAV RNA. HAV viremia was correlated to ALT peak (r = .64; P < .0001). HIV-infected patients have similar HAV RNA levels but were less likely to have prolonged international normalized ratio of prothrombin time when compared to the HIV-uninfected group (P = .016), suggesting a less severe course of acute hepatitis. HAV RNA was detected in the serum of most of the patients with acute hepatitis A, indicating that the direct detection of HAV can be used to confirm hepatitis A in patients tested positive for anti-HAV IgM antibodies. Nucleic acid tests should serve more broadly during the diagnosis workup of acute hepatitis A to improve the predictive values of HAV in vitro diagnostic tests and to confirm acute hepatitis A in patients tested positive with IgM with moderate or low S/CO values.

New 4-phenylcoumarin derivatives as potent 3C protease inhibitors: Design, synthesis, anti-HAV effect and molecular modeling.

A new series of 4-phenylcoumarin derivatives was synthesized starting from (2-oxo-4-phenyl-2H-chromen-7-yloxy) acetic acid hydrazide 3. Evaluation of the target compounds for their antiviral activity against hepatitis A virus revealed that the ethylthiosemicarbazide derivative 7b was the most potent virucidal agent (IC50 = 3.1 µg/ml, TI = 83). The Schiff's bases 14c and 14b demonstrated the highest virustatic effects against viral adsorption and replication, respectively (14c; IC50 = 8.5 µg/ml, TI = 88 and 14b; IC50 = 10.7 µg/ml, TI = 91). Furthermore, compounds 7b, 14b and 14c were tested against HAV 3C protease and showed significant inhibition effects (Ki = 1.903, 0.104 and 0.217 µM, respectively). The remarkable inhibitory effect expressed by the three target compounds against HAV 3C protease prompted us to expand our research on HRV 3C protease, a structurally related enzyme of the same family, and interestingly, the three target compounds displayed significant inhibitory effect against HRV 3C protease (IC50 = 16.10, 4.13 and 6.30 µM, respectively). Moreover, the active compounds 7b, 14b and 14c were docked within the pocket site of HAV 3C protease (PDB code: 2HAL) illustrating a strong H-profile with the key amino acids Gly170 and Cys172 similar to the co-crystallized ligand. Furthermore, 3D-pharmacophore and quantitative structure activity relationship (QSAR) models were generated to explore the structural requirements for the observed antiviral activity.

Age-stratified anti-HAV positivity in Pune, India after two decades: Has voluntary vaccination impacted overall exposure to HAV?

The degree of transmission of hepatitis A virus (HAV) is inversely proportional to the socioeconomic status of a community. Serosurveys conducted at Pune, India during 1982-98 documented significant reduction in HAV exposure of paediatric, higher socioeconomic status (HSS) population. Anti-HAV positivity (ELISA) in age-stratified Pune population representing HSS and lower middle socioeconomic status (LMSS) (n = 1065) and infants till the age of 15 months (n = 690) was determined in 2017. Anti-HAV positivity in the LMSS population decreased significantly in 2017 while an increase was seen in the HSS category. The surprising rise in anti-HAV positivity in the HSS population reflected vaccine- and infection-induced antibodies while only infection-induced antibodies were present in the LMSS category. Lowest antibody prevalence in infants was at 12 months, the recommended age for hepatitis A vaccination. Improved hygiene and selective immunization practices impacted HAV exposure of the LMSS population. The data emphasize the need for hepatitis A vaccination irrespective of socioeconomic status.

[Markers of hepatitis A in the monkeys of the Adlers primate center.]

Hepatitis A is a widespread viral infection. The HAV strains of "human" and "monkey" origin are similar in their morphological and antigenic properties, but differ genotypically. OBJECTIVES: The aim of this research was a comparative study of serological and molecular-genetic markers of HAV infection in monkeys born at the Adler Primate Center and in those imported from different countries. MATERIAL AND METHODS: Fecal samples (n = 313) and serum (n = 266) from various species of monkey using ELISA and RT-PCR were studied. RESULTS AND DISCUSSION: The frequency of anti-HAV-IgG was high (78.9%) in imported animals (vervet monkeys from Tanzania and cynomolgus monkeys from Vietnam) and as well as in various species of monkeys (rhesus monkeys, cynomolgus monkeys, green monkeys and papio hamadryas) of the Center (88.6%). At the same time, in the imported monkeys, the markers of "fresh" HAV infection (IgM-27.2%, Ag-HAV-16.7%, RNA-22.0%) were detected significantly more often (p> 0.05) than in monkeys kept at the Colony (IgM-7.5%, HAV-Ag - 5.2%, RNA - 3.6%). In general, anti-IgG reactivity ranged from 1.064 to 2.073 OD450, anti-IgM ranged from 0.546 to 1.059 OD450. The number of HAV-Ag was 0.496 - 1.995 OD450. RNA HAV only in rhesus monkeys and cynomolgys monkeys born at the Colony, as well as in imported vervet monkeys was detected. CONCLUSIONS: The data obtained indicate a wide circulation of HAV among monkeys born in the Adler Primate Center and among the imported animals. Markers of "fresh" HAV infection varied depending on the species of monkeys and their origin.

Hepatitis A virus vaccination in childhood-onset systemic lupus erythematosus.

OBJECTIVES: Vaccination of systemic lupus erythematosus patients with non-live vaccines may decrease vaccine-preventable infections and mortalities. In the present study, we aimed to compare the immunogenicity and safety of inactivated hepatitis A vaccination in childhood-onset systemic lupus erythematosus and healthy subjects. METHODS: A total of 30 childhood-onset systemic lupus erythematosus and 39 healthy participants who were seronegative for hepatitis A received two doses of the hepatitis A vaccine in a 0- and 6-month schedule. Hepatitis A virus (HAV) IgG antibodies were measured before vaccination and 7 months after the vaccination. RESULTS: Although anti-HAV IgG antibody titers after vaccination were found to be somewhat lower in children with systemic lupus erythematosus than that of the healthy subjects ( p < 0.05), the difference in seroconversion rate was insignificant between childhood-onset systemic lupus erythematosus patients ( n = 24/30, 80%) and healthy controls ( n = 33/39, 84.6%). There was no increase in median Systemic Lupus Erythematosus Disease Activity Index (SLEDAI)-2K scores and anti-ds DNA levels after the vaccination procedure. Seroconversion rates in childhood-onset systemic lupus erythematosus patients were not affected by medication, high disease activity (SLEDAI-2K >6) and anti-ds DNA positivity. None of the patients experienced any flare or adverse reaction throughout the study. CONCLUSIONS: According to these results, we conclude that inactivated hepatitis A vaccine is safe and well tolerated in childhood-onset systemic lupus erythematosus patients, with no adverse events or increase in activity. Immunogenicity to the hepatitis A vaccine was adequate, with a seropositivity rate of 80%.

Initial evaluation of universal immunization with a single dose against hepatitis A virus in Central Brazil

ABSTRACT Vaccination against the hepatitis A virus (HAV) administered in two doses has been used effectively in universal child immunization programs in several countries. A single-dose vaccination was adopted in some low-income countries in an attempt to reduce costs without losing effectiveness. In 2014, single-dose universal vaccination was introduced in Brazil for children aged two years. Since such strategy is still not universally accepted, its efficacy should be compared to the two-dose strategy. To assess the humoral response after the single-dose HAV vaccination schedule, a cross-sectional study was conducted in Primavera do Leste, in Mato Grosso state, Central Brazil, including 265 children vaccinated through the National Immunization Program. Blood was collected by using a digital puncture and further applied to filter paper cards. Anti-HAV was detected in 218 out of 265 dried blood spots (DBS). Blood venous samples were collected from 34 out of 47 children who were not anti-HAV positive in DBS samples. Eighteen of them tested positive for anti-HAV, giving a final score of 93.6% (236/252) of seropositivity. In conclusion, this study demonstrated a high rate of anti-HAV positivity in the short term after single-dose hepatitis A vaccination in the population investigated. Moreover, the DBS was shown to be a reliable tool for detecting anti-HAV antibodies.

Initial evaluation of universal immunization with a single dose against hepatitis A virus in Central Brazil.

Vaccination against the hepatitis A virus (HAV) administered in two doses has been used effectively in universal child immunization programs in several countries. A single-dose vaccination was adopted in some low-income countries in an attempt to reduce costs without losing effectiveness. In 2014, single-dose universal vaccination was introduced in Brazil for children aged two years. Since such strategy is still not universally accepted, its efficacy should be compared to the two-dose strategy. To assess the humoral response after the single-dose HAV vaccination schedule, a cross-sectional study was conducted in Primavera do Leste, in Mato Grosso state, Central Brazil, including 265 children vaccinated through the National Immunization Program. Blood was collected by using a digital puncture and further applied to filter paper cards. Anti-HAV was detected in 218 out of 265 dried blood spots (DBS). Blood venous samples were collected from 34 out of 47 children who were not anti-HAV positive in DBS samples. Eighteen of them tested positive for anti-HAV, giving a final score of 93.6% (236/252) of seropositivity. In conclusion, this study demonstrated a high rate of anti-HAV positivity in the short term after single-dose hepatitis A vaccination in the population investigated. Moreover, the DBS was shown to be a reliable tool for detecting anti-HAV antibodies.

Seroprevalence of anti-HAV total antibodies among workers in wastewater treatment plants.

OBJECTIVES: Data on high frequency of hepatitis A virus (HAV) antibodies for wastewater treatment staff is contradictory. Literature lacks data on the seroprevalence of antibodies to HAV (anti-HAV) among workers in wastewater treatment plants (WWTPs) in Bulgaria. The aim of this study is to establish a specific humoral immune response to hepatitis A virus - anti-HAV total antibodies among staff in WWTPs. MATERIAL AND METHODS: A complex study of health and working conditions included 110 subjects working in 3 WWTPs in Bulgaria (74% of all workers in the 3 studied WWTPs and 20% of all employees in Bulgaria registered in 2014 under the wastewater collection, discharge and treatment code of economic activity). Workers had been differentiated in 3 groups on the basis of their occupational work: operators, support staff and other workers exposed to biological agents. Venous blood from all 110 subjects was tested once for carriers of HAV antibodies. RESULTS: Anti-HAV total antibodies were found for 52.7% of workers in WWTPs. There is a positive association between activity performed in WWTPs (operators, maintenance personnel and others exposed) and a positive one for the presence of anti-HAV (Chi2 = 6.882, df = 2, p = 0.032). Odds ratio (OR) for hepatitis A increases 2.9 times in the group of operators vs. others exposed to biological agents in WWTPs (OR = 2.914, 95% confidence interval (CI): 1.149-7.393, Fisher's p = 0.039). Odds ratio for hepatitis A increases 4.3 times in the group of support staff from WWTPs vs. others exposed to biological agents in WWTP (OR = 4.295, 95% CI: 1.075-17.167, Fisher's p = 0.049). CONCLUSIONS: Higher frequency of anti-HAV antibodies among operators and maintenance personnel at WWTPs has been established as compared to other workers exposed to biological agents in WWTPs. There is a positive association between increasing age of the workers and the presence of anti-HAV. Int J Occup Med Environ Health 2018;31(3):307-315.

The frequency of occurrence anti-HAV antibodies to health employees ­ own observations

INTRODUCTION: In the years 1997-2016, Poland was counted among the countries with a low and very low endemicity of hepatitis A. Based on the epidemiological data from NIZP­PZH (National Institute of Public Health - National Institute of Hygiene), since 2017, an increase in the incidence of hepatitis A has been observed in Poland. Considering the low number of cases by 2016 and a high percentage of seronegative persons, an increased risk of HAV infections should be expected. OBJECTIVE: The aim of the project was to assess the presence of anti-HAV IgG antibodies in the employees of the Provincial Hospital for Infectious Diseases and Observation in Bydgoszcz. MATERIAL AND METHODS: The study was conducted on 123 people who are employees of the hospital. The presence of anti-HAV antibodies was detected using HAV IgG Elisa FORTRESS DIAGNOSTICS kits. RESULTS: The presence of anti-HAV IgG antibodies was found in 28/123 (22.8%) subjects. Anti-HAV IgG antibodies were almost exclusively found in people over 40 years of age. Only one case involved a younger person. CONCLUSIONS: The low incidence of anti-HAV antibodies in the IgG class among medical personnel confirms the reasonableness of vaccinations against hepatitis A in this group.

The knowledge and high seroprevalence of hepatitis A in a high-risk group (agricultural reproductive-aged women) in the southeastern region of Turkey

Background/aim: The aim of this study was to determine the seroprevalence of antihepatitis A virus (HAV), risk factors, and the knowledge of female farm workers living in the Southeastern Anatolia Region (SAR) of Turkey. Materials and methods: This representative cross-sectional survey was conducted between January and April of 2013 in the SAR. A total of 705 reproductive-aged women were randomly selected by clustering method using Epi Info software. The sera were analyzed for anti-HAV antibodies using ELISA. Sociodemographic information and the knowledge of female farm workers regarding hepatitis A were collected using a questionnaire. Results: Of the female farm workers, 99.1% were seropositive for anti-HAV. The anti-HAV seroprevalence was significantly higher in the adults than in the adolescents (P < 0.05). Of the participants, 64.5% had 7 or more family members, 58.4% had 5 or more pregnancies, 68.1% were illiterate, 65.2% were family farmers, 90.6% were poor, 71.9% used unsafe water, 58.9% had toilets outside, and 68% had no knowledge about hepatitis A. Conclusion: Turkey is considered to have high endemicity and female farm workers are considered a high-risk group for hepatitis A. This high HAV exposure might be reduced with vaccination, as well as improvements in sanitation, living conditions, health care utilization, safer drinking water, and health education.

Immunogenicity and estimation of antibody persistence following vaccination with an inactivated virosomal hepatitis A vaccine in adults: A 20-year follow-up study.

PURPOSE: This was a 20-year follow-up study to assess long-term persistence of protective antibody levels against the hepatitis A virus (HAV) in healthy participants vaccinated with 2 doses of inactivated hepatitis A vaccine (Epaxal®) between 1992 and 1995. METHODS: Blood samples for anti-HAV antibody concentrations were obtained during a follow-up visit 20years after vaccination and were analyzed in parallel with samples still available from previous visits using AxSYM® HAVAB 2.0 assay. RESULTS: Mean (SD) age of the participants was 44.71 (3.905) years at year 20 follow-up (N=95). Participants completing 0/12-month Epaxal® immunization regimen (N=94) had seroprotection rate of 100% (95% CI: 96.2, 100.0) with ⩾10mIU/mL seropositivity cut-off and 98.9% (95% CI: 94.2, 100.0) with ⩾20mIU/mL cut-off. With ⩾10mIU/mL cut-off, the estimated median duration of protection was 77.3years (95% CI: 71.8, 83.5) with 95% of the vaccinated participants predicted to be protected for at least 41.5years. At ⩾20mIU/mL cut-off, the estimated median duration of protection was 64.8years (95% CI: 60.1, 68.4) with 95% of the vaccinated participants predicted to be protected for at least 33years. Anti-HAV antibody geometric mean concentrations were higher in women (277.9; 95% CI: 217.7, 354.7) than in men (167.7; 95% CI: 125.2, 224.6). CONCLUSION: The data from this 20-year follow-up study confirm previous observations that two doses of Epaxal® provide protection against hepatitis A infection for at least 30years in over 95% of healthy participants.

Immunity to hepatitis A and B persists for at least 15 years after immunisation of adolescents with a combined hepatitis A and B vaccine.

BACKGROUND: The exact duration of antibody persistence to hepatitis A and B and the need for booster dosing following primary immunisation remains undefined. A long-term study was designed to follow antibody persistence and immune memory on an annual basis for up to 15 years following vaccination during adolescence. METHODS: Subjects received a combined hepatitis A and B vaccine (Twinrix™, GSK Vaccines, Belgium) at 12-15 years of age, either as 2-dose of the adult formulation or 3-dose of the paediatric formulation. Blood samples were taken every year thereafter to assess antibody persistence and immune memory to hepatitis A and B. Antibodies to hepatitis A virus (anti-HAV) and hepatitis B surface antigen (anti-HBs) were measured at Years 11-15. At Year 15 immune memory was further assessed by measuring the anamnestic response to a challenge dose of the monovalent vaccine, which was administered to subjects whose antibody concentrations fell below the pre-defined cut-offs (anti-HAV: <15mIU/mL; anti-HBs: <10mIU/mL). RESULTS: 209 subjects returned for follow-up at Year 15 of whom 162 were included in the long-term according-to-protocol immunogenicity cohort. All subjects remained seropositive for anti-HAV antibodies, while 81.1% and 81.8% still had anti-HBs antibodies ≥10mIU/mL in the 2- and 3-dose groups, respectively. Following hepatitis B vaccine challenge dose administration to 19 subjects, all except one in the 3-dose group, mounted a robust anamnestic response. The safety and reactogenicity profile of the hepatitis B challenge was consistent with previous experience. CONCLUSION: Immunity to hepatitis A and B persists 15 years after adolescent vaccination with a combined hepatitis A and B vaccine. Highly effective anamnestic response indicates that a booster dose should not be required for 15 years after primary vaccination. TRIAL REGISTRATION: http://www.clinicaltrials.govNCT00875485.

Viral excretion and antibody titers in children infected with hepatitis A virus from an orphanage in western India.

BACKGROUND: Hepatitis A is endemic in India and mainly causes sporadic infections. However, children in childcare centers, schools and orphanages are vulnerable to common-source outbreaks as they have naive hosts. OBJECTIVES: To investigate hepatitis A outbreak in an orphanage from Pune, India. STUDY DESIGN: Monitoring of virus excretion and anti-HAV antibody levels in hepatitis A virus (HAV) infected children. RESULTS: The orphanage housed 93 children of the age 1 month-6.5 years. Analysis of the collected serum (n=78) and stool samples (n=63) revealed 20 children to be either positive for anti-HAV IgM antibodies or excreting HAV, 14 being symptomatic and 6 asymptomatic, while 32 were already anti-HAV IgG positive either due to past HAV exposure (n=7, mean log antibody titers: 2.96) or maternal antibodies (n=25, mean log antibody titers: 1.13). Serum samples, taken 4 weeks apart, did not show any significant difference in the IgM and IgG antibody levels either. However, virus excretion decreased significantly after 15 days in symptomatic children (mean log HAV RNA copies/ml 1.03+0.30), while asymptomatic children continued to excrete higher viral loads, at constant levels (mean log HAV RNA copies/ml 2.33+0.33), for up to 90 days. CONCLUSIONS: Though virus excretion continued up to 90 days in all HAV infected children, asymptomatic children excreted higher viral loads for longer period and hence can contribute significantly in person-to-person virus transmission. All children should be vaccinated in such set ups.

The changing pattern of hepatitis A in Lebanese adults.

OBJECTIVE: A shift in the age of hepatitis A virus (HAV) infection from early childhood to adulthood has been observed in many developing countries. This epidemiological shift has been attributed to improved socioeconomic status and sanitary conditions resulting in growing cohorts of susceptible young people and hence an increased risk of HAV outbreaks. The aim of this study was to investigate the evolutionary trend of anti-HAV seroprevalence in Lebanon in a cohort of Lebanese adults. METHODS: This was a cross-sectional study employing a convenience sample (voluntary blood donors) along with secondary data analysis. Sera from 283 healthy blood donors were tested for anti-HAV IgG antibodies. Moreover, we analyzed the national reports of HAV cases published by the Lebanese Ministry of Public Health since 2001. RESULTS: Anti-HAV seropositivity increased steadily from 60% in the younger age group (19-29 years) to 91% in the older age group (50-59 years), leaving the younger group at higher risk of acquiring HAV. The national data show that the number of acute hepatitis A infections is higher in the age groups 5-9 and 10-19 years. CONCLUSION: Our seroprevalence data reveal that young adults are becoming more at risk of acquiring HAV infection. Thus the introduction of hepatitis A vaccine is highly recommended.