Hepatitis A in Latin America: The current scenario.

This review aims to gather and disseminate updated information regarding hepatitis A virus (HAV) in Latin America (LA) in the last 11 years, including seroprevalence, post-vaccination studies, virus detection in aqueous matrices and food samples, and outbreak reports. Only 24 seroprevalence studies were published between 2012 and 2023 with 55%-100% reported prevalences of anti-HAV IgG. Among the 25 LA countries, only eight of them have introduced HAV vaccines into their immunisation programs. Outbreaks of hepatitis A occurred between 2017-2019, mainly affecting men who have sex with men in Argentina, Brazil and Chile, probably as a consequence of the abrupt decline of young adults' immunity. This could be due to that young adult have never been infected in childhood (due to socio-health improvements) and are above the cut-off ages to be included when the vaccination programs were introduced. Although scarce, studies focused on environmental and food HAV surveillance have shown viral presence in these samples. Surface waters presented HAV detections between 1.2% and 86.7%, and untreated wastewaters between 2.8% and 70.9%. Genotypes found in all cases were IA and IC. The only wastewater-based epidemiology study showed to be a useful tool as a complement of traditional epidemiological surveillance. Only four LA countries have looked for HAV in food samples, with genome detection rates between 9% and 33%. Latin American HAV circulation scenario is changing. In countries where socioeconomic and sanitary conditions have not improved, the virus persists with high endemicity and the access to the vaccine should be re-evaluated by local governments. In countries where access to clean water, better sanitary conditions and HAV immunisation programs have been implemented, the number of cases among young adults seems to be increasing, alerting health authorities.

Antibody persistence 7 years after hepatitis-A vaccine in children with human immunodeficiency virus infection.

BACKGROUND: HIV-infected children have a higher risk of presenting infections, including the hepatitis A virus (HAV). The inactivated HAV vaccine is immunogenic in immunocompetent hosts; however, there are insufficient studies on the duration of seroprotection in HIV-infected children. METHODS: An analytical cohort study was conducted. HIV-1-infected children who received the inactivated HAV vaccine (2 doses) were included. Blood samples were taken for antibody measurement, the first one 28 days after the second dose and another 7 years after the vaccination schedule. Information on viral load, immunological category, weight, height, and response to antiretroviral treatment from diagnosis to the last assessment was obtained. RESULTS: 19 patients were included, with a mean age of 12.6 years (SD ± 2.29). 58% were male. 80% of the patients presented protective immunoglobulin G antibodies against HAV 7-year post-vaccination. The antibody concentration was found to be between 13 and 80 mIU/mL (median of 80 mIU/mL). 52% showed some degree of immunosuppression. There was no statistically significant relationship between the presence of seroprotection and viral load, treatment failure, immunological category, and malnutrition. Twelve patients presented with antiretroviral treatment failure, and in 33% of them, the antibodies did not offer satisfactory seroprotection. CONCLUSION: 7-year post-vaccination, 80% of HIV-infected children maintain seroprotection titers against HAV.

INTRODUCCIÓN: Los niños infectados por el virus de la inmunodeficiencia humana (VIH) tienen mayor riesgo de presentar infecciones, incluyendo hepatitis por virus A (VHA). La vacuna inactivada contra el VHA es inmunógena en el huésped inmunocompetente. No hay estudios suficientes sobre el tiempo de seroprotección en niños infectados por el VIH. MÉTODO: Estudio de cohorte, analítico. Se incluyeron niños con infección por VIH-1 que recibieron la vacuna inactivada contra el VHA (dos dosis). Se les tomaron muestras sanguíneas para medición de anticuerpos, una 28 días después de la segunda dosis y otra 7 años después del esquema de vacunación. Se obtuvo información de carga viral, categoría inmunológica, peso y talla, y respuesta al tratamiento antirretroviral desde el diagnóstico hasta la última valoración. RESULTADOS: Se incluyeron 19 pacientes con una edad media de 12.6 años (± 2.29). El 58% fueron del sexo masculino. El 80% de los pacientes presentaron anticuerpos immunoglobulin G (IgG) contra el VHA protectores a los 7 años de la vacunación. La concentración de anticuerpos se encontró entre 13 y 80 mUI/ml (mediana: 80 mUI/ml). El 52% mostraron algún grado de inmunosupresión. No existe relación estadísticamente significativa entre la presencia de seroprotección y la carga viral, la falla al tratamiento, la categoría inmunológica ni la desnutrición. Doce pacientes presentaron falla al tratamiento antirretroviral; en el 33% de ellos los anticuerpos no ofrecían seroprotección satisfactoria. CONCLUSIONES: A 7 años posvacunación, el 80% de los niños con VIH mantienen títulos de seroprotección frente al VHA.

Seroprevalence of hepatitis A virus among people born before and after implementation of universal vaccination in Argentina.

BACKGROUND: Until 2005, when a single dose of vaccine was implemented in one-year-old children, the Hepatitis A virus (HAV) was responsible for approximately 90% of acute hepatitis cases in the paediatric population in Argentina. However, despite vaccination success, sporadic outbreaks of HAV still occur among adults. This study aimed to assess the seroepidemiology of HAV in Argentina, analysing IgG and IgM antibodies against HAV in a large population, both vaccinated and unvaccinated. METHODS: The study included 16,982 patients attending a hospital from 2001 to 2023. The cohort was divided into two groups: 16,638 individuals who were not reached by the vaccination program implemented in 2005 and 344 children who were covered by the universal vaccination. RESULTS: Anti-HAV IgG was detected in 56.7% of cases. The rate was significantly higher in individuals born after 2005 (77.7%) compared to those born before (56.3%), p < 0.001. The age groups 19-40 and 41-60 years showed the anti-HAV IgG lowest rates. On the other hand, 100/3956 cases (2.5%) with suspected acute hepatitis were positive for Anti-HAVIgM. Notably, none of these were born after the mandatory vaccine rollout. CONCLUSIONS: The study of this large cohort contributes to the understanding of the seroepidemiology of HAV. Although the implementation of the vaccine achieved its main goal, the age segment between 19 and 60 years does not reach the estimated threshold to achieve herd immunity. These findings reveal the importance of targeting vaccination campaigns, provide essential insights for public health planning, and guide future immunisation strategies against HAV in Argentina.

Association between hepatitis A seropositivity and bone mineral density in adolescents and adults: a cross-sectional study using NHANES data.

BACKGROUND: Osteoporosis, characterized by decreased bone density and increased fracture risk, imposes significant physical, psychosocial, and financial burdens. Early detection and prevention are crucial for managing osteoporosis and reducing the risk of fractures. OBJECTIVES: To investigate the relationship between Hepatitis A seropositivity and bone mineral density (BMD) in adolescents and adults and to explore the potential link between Hepatitis A infection and osteoporosis risk. DESIGN AND SETTING: This cross-sectional study used data from the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2018 to evaluate the association between hepatitis A seropositivity and BMD in 15,693 participants. METHODS: Multivariable regression analysis was used to calculate the mean BMD and standard error for adolescents and adults, followed by an independent z-test to determine whether there was a significant difference between the seropositive and seronegative groups. RESULTS: Hepatitis A seropositive adolescents and adults had lower BMD than their seronegative counterparts, with significant differences in lumber spine (mean difference = -0.03 g/cm2, P < 0.01 for both age groups) and pelvis BMDs (mean difference = -0.02 g/cm2, P < 0.01 for the adult age groups), after adjusting for various covariates. CONCLUSIONS: This study confirmed that both adolescent and adult individuals seropositive for Hepatitis A antibodies had reduced BMD among both adolescents and adults, especially in the adult group. This finding suggests a possible link between Hepatitis A infection and risk of osteoporosis.

Factors associated with hepatitis A susceptibility among men who have sex with men using HIV pre-exposure prophylaxis in Northeastern Brazil: A cross-sectional study.

Hepatitis A virus (HAV) infection has disproportionately affected more men who have sex with men (MSM), occurring in outbreaks, despite being vaccine-preventable. We determined the prevalence and factors associated with HAV susceptibility among cisgender MSM on HIV pre-exposure prophylaxis (PrEP) in Northeastern Brazil. From September 30, 2021 to June 19, 2023, 282 cisgender MSM receiving HIV PrEP were enrolled into this cross-sectional study. Sociodemographic and clinical information were collected. Blood samples were collected for screening of sexually transmitted infections (STIs) and serum samples were tested for IgM and total anti-HAV antibodies. Non-reactive results for total anti-HAV antibodies were found in 106 of 282 (37.6%) participants. Factors associated with HAV susceptibility included age <30 years (prevalence ratio [PR]: 2.02; 95% confidence interval [95% CI]: 1.61-2.53), having health insurance (PR: 1.39; 95% CI: 1.19-1.64), sex only with cisgender men (PR: 1.52; 95% CI: 1.23-1.89), non-steady partner (PR: 1.20; 95% CI: 1.01-1.43) and no lifetime history of STIs (PR: 1.25; 95% CI: 1.03-1.53). Identifying clinical correlates of HAV susceptibility in key populations is a fundamental step towards development of public policy focused on prevention, especially following the recent hepatitis A outbreak in Brazil.

Hepatitis A virus infection in Brazilian correctional facilities.

Hepatitis A virus (HAV) infection is transmitted by the fecal-oral route, through interpersonal contact and ingestion of contaminated food or water. Prisoners are at higher risk of acquiring HAV infection mainly due to the environment of closed penal institutions and socioeconomic conditions. This study aims to determine the seroprevalence of anti-HAV and its associated risk factors among inmates from twelve prisons in Central Brazil. A cross-sectional study was conducted between March 2013 and March 2014. A total of 580 prisoners participated in the study. The participant's samples were tested for Total and IgM anti-HAV antibodies by electrochemiluminescence immunoassay (ECLIA). Risk factors associated with anti-HAV seropositivity were also analyzed. The prevalence rate of HAV exposure was 88.1% (95% CI: 85.5-90.7). No sample had a positive reaction to IgM anti-HAV. Increasing age, low level of education, and being imprisoned in Corumbá city were independently associated with HAV exposure among prisoners. To prevent the burden of the disease, vaccination strategies should be considered for susceptible prisoners in Central Brazil.

Persistence of immunity against hepatitis A in Brazilian children vaccinated with a single dose of inactivated virus vaccine.

In 2014, the Brazilian National Immunization Program implemented the universal vaccination against the hepatitis A virus (HAV) for children aged 12 months and older, applying a single dose of the inactivated virus vaccine. It is essential to carry out follow-up studies in this population, aiming to verify the longevity of HAV immunological memory. This study evaluated the humoral and cellular immune response of a cohort of children vaccinated between 2014 and 2015, and further investigated between 2015 and 2016, and who had their initial antibody response assessed after the single dose. A second evaluation took place in January 2022. We examined 109 children out of the 252 that took part in the initial cohort. Seventy (64.2%) of them had anti-HAV IgG antibodies. Cellular immune response assays were performed in 37 anti-HAV-negative and 30 anti-HAV-positive children. Production of interferon-gamma (IFN-y) stimulated with the VP1 antigen was demonstrated in 34.3% of these 67 samples. Of the 37 negative anti-HAV samples, 12 (32.4%) produced IFN-y. Among the 30 anti-HAV-positive, 11 (36.7%) produced IFN-y. In total, 82 (76.6%) children presented some type of immune response against HAV. These findings demonstrate the persistence of immunological memory against HAV in the majority of children vaccinated between 6 and 7 years with a single dose of the inactivated virus vaccine.

Ethnic differences in hepatitis A and E virus seroprevalence in patients attending the Emergency Department, Paramaribo, Suriname.

BACKGROUND: Hepatitis A virus (HAV) and hepatitis E virus (HEV) have enteric modes of transmission and are common causes of acute hepatitis in low- and middle-income countries. HEV is also characterised as a zoonotic infection and is prevalent in high-income countries. Data on HAV and HEV prevalence in Suriname, a middle-income country in South America, are scarce. METHODS: Serum samples of 944 and 949 randomly selected patients attending the Emergency Department at the Academic Hospital of Paramaribo, the capital of Suriname, were analysed for anti-HAV antibodies (anti-HAV) and anti-HEV antibodies (anti-HEV), respectively. Determinants of anti-HAV and anti-HEV positive serology were evaluated using multivariable logistic regression. RESULTS: Anti-HAV prevalence was 58.3% (95% CI 55.4 to 61.4%) and higher prevalence was independently associated with belonging to the Tribal or Indigenous population and older age. Anti-HEV prevalence was 3.7% (95% CI 2.6 to 5.0%) and higher prevalence was associated with Tribal and Creole ethnicity and older age. CONCLUSIONS: In Suriname, exposure to HAV is consistent with a very low endemic country and exposure to HEV was rare. Both viruses were more prevalent in specific ethnic groups. As anti-HAVantibodies were less frequently found in younger individuals, they could be susceptible to potential HAV outbreaks and might require HAV vaccination.

Hepatitis A and E among immigrants and refugees in Central Brazil.

OBJECTIVE: To estimate the prevalence of hepatitis A virus (HAV) and hepatitis E virus (HEV) among immigrants and refugees in Goiás, Central Brazil. METHODS: Overall, 355 individuals were interviewed, and blood samples were tested for anti-HAV and anti-HEV IgG. Anti-HEV-positive samples were similarly tested for HEV RNA. RESULTS: All participants were from Latin American countries, most of whom, young adult males. The overall anti-HAV IgG prevalence was 87.4% (95%CI: 83.5-90.4), of whom 94.9%, 75.6%, and 60% were from Haiti, Venezuela, and other Latin American countries, respectively (p < 0.001). Age above 19 years and more than 36 months residing in Brazil were associated with a higher prevalence of previous HAV and HEV infection, respectively. Of the children eligible for HAV vaccination according to the National Immunization Program, only eight (44%) had been vaccinated. The overall anti-HEV IgG prevalence was 6.5% (95%CI: 4.4-9.5). All anti-HEV IgG-positive individuals were Haitians, including a child born in Brazil. HEV RNA was detected in two of the anti-HEV IgG-positive samples. CONCLUSION: The survey detected a high prevalence of anti-HAV and anti-HEV IgG among immigrants and refugees, and active HEV infection among some Haitian participants. Prevention measures are urgently required to interrupt enteric virus transmission in this emergent and vulnerable population.

The first evidence of hepatitis A virus subgenotype IIIA in the Eastern Brazilian Amazon, 1982-1983.

Hepatitis A virus (HAV) is a major causative agent of acute hepatitis worldwide. Although discovered in 1973, due to limitations of applicable serological and/or molecular methods, HAV remained under limited diagnosis until the late 1980s. This study aimed to retrospectively evaluate the serological and molecular prevalence of the HAV infection among 421 (n = 421) patients with a clinical and laboratory suspicion of acute hepatitis who were admitted in a reference laboratory in the Brazilian Eastern Amazon during 1982 and 1983. The 421 serum samples were screened for anti-HAV IgM antibodies by enzymatic immunoassays. Positive samples were submitted to total RNA purification and tested by Nested reverse-transcription polymerase chain reaction to amplify the HAV-RNA VP1-2A (522 bp) region. Anti-HAV IgM antibodies were detected in 66% (278/421) of the patients. The highest prevalence was observed among males (57.9%, 161/278), and most often among children under 10 years old (63.3%, 176/278). HAV-RNA was detected in 74.4% (207/278) of anti-HAV IgM positive samples. HAV genotyping was performed in 71 samples, and 69 were classified into subgenotype IA. Two samples belonged to the HAV subgenotype IIIA. In this sense, retrospective studies can help in understanding the evolution and determination of wild genotypes and subtypes of HAV.

Humoral and cellular immune memory response 12 years following single dose vaccination against hepatitis A in Argentinian children.

Infants' universal hepatitis A virus (HAV) single-dose vaccination has been highly effective for controlling HAV infection in Argentina, and in other Latin-American countries that adopted that strategy. Although antibodies wane over time, this has not been associated with HAV outbreaks or breakthrough infections, suggesting a relevant role for memory immunity. This study assessed long term humoral and cellular immune memory response after an average of 12 years follow-up of HAV single-dose vaccination. We selected 81 HAV-single dose vaccinated individuals from a 2015 study, including 54 with unprotective (UAL) and 27 with protective antibody levels (PAL) against HAV. Humoral memory response was assessed by measuring anti-HAV antibody titers at admission in both groups, and 30 days after a booster dose in the UAL group. Flow cytometry analysis of peripheral blood mononuclear cell samples stimulated with HAV antigen was performed in 47/81 individuals (21 with PAL, 26 with UAL) to identify activated CD4 + memory T cells or CD8 + memory T cells. The results showed that 48/52 (92%) individuals from UAL group who completed follow up reached protective levels after booster dose. In the PAL group, anti-HAV Abs waned in 2/27 (7%) individuals lacking seroprotection, while in 25/27 (93%) Abs remained >10 mUI/mL. HAV-specific memory CD4 + T cells were detected in 25/47 (53.2%) subjects while HAV-specific memory CD8 + T cells were observed in 16/47 (34.04%) individuals. HAV-specific memory CD4+ and CD8+ T cell responses were detected in 11/21 (52.4%) and in 9/21 (42.9%) subjects with PAL and in 14/26 (53.8%) and in 7/26 (26.9%) individuals with UAL, showing that the presence of memory T-cells was independent of the level or presence of anti-HAV antibodies. Long-term immunity demonstrated in the present work, including or not antibody persistence, suggests that individuals with waned Ab titers may still be protected and supports the single-dose HAV strategy.

Hepatitis A and E among immigrants and refugees in Central Brazil

ABSTRACT OBJECTIVE To estimate the prevalence of hepatitis A virus (HAV) and hepatitis E virus (HEV) among immigrants and refugees in Goiás, Central Brazil. METHODS Overall, 355 individuals were interviewed, and blood samples were tested for anti-HAV and anti-HEV IgG. Anti-HEV-positive samples were similarly tested for HEV RNA. RESULTS All participants were from Latin American countries, most of whom, young adult males. The overall anti-HAV IgG prevalence was 87.4% (95%CI: 83.5-90.4), of whom 94.9%, 75.6%, and 60% were from Haiti, Venezuela, and other Latin American countries, respectively (p < 0.001). Age above 19 years and more than 36 months residing in Brazil were associated with a higher prevalence of previous HAV and HEV infection, respectively. Of the children eligible for HAV vaccination according to the National Immunization Program, only eight (44%) had been vaccinated. The overall anti-HEV IgG prevalence was 6.5% (95%CI: 4.4-9.5). All anti-HEV IgG-positive individuals were Haitians, including a child born in Brazil. HEV RNA was detected in two of the anti-HEV IgG-positive samples. CONCLUSION The survey detected a high prevalence of anti-HAV and anti-HEV IgG among immigrants and refugees, and active HEV infection among some Haitian participants. Prevention measures are urgently required to interrupt enteric virus transmission in this emergent and vulnerable population.

Detection of Antibodies against Hepatitis A Virus (HAV) by a Surface Plasmon Resonance (SPR) Biosensor: A New Diagnosis Tool Based on the Major HAV Capsid Protein VP1 (SPR-HAVP1).

Hepatitis A (HA) is an acute human infectious disease caused by a positive single-stranded RNA virus (HAV). It is mainly acquired through the fecal-oral route and is primarily spread by contact between people and exposure to contaminated water and food. Recently, large outbreaks of HA have been reported by low and moderate endemicity countries, emphasizing its importance in public health and the need for rapid and large-scale diagnostic tests to support public health decisions on HA. This work proposes a new tool for HAV diagnosis based on the association of surface plasmonic resonance with major capsid protein VP1 (SPR-HAVP1 assay), detecting IgM antibodies for HAV in human serum samples. Structural analyses of VP1 B-lymphocyte epitopes showed continuous and discontinuous epitopes. The discontinuous epitopes were identified in the N-terminal region of the VP1 protein. Both epitope types in the VP1 protein were shown by the reactivity of VP1 in native and denaturing conditions to IgM anti-HAV, which was favorable to tests of VP1 in the SPR assays. SPR-HAVP1 assays showed good performance in the detection of IgM polyclonal antibody anti-HAV. These assays were performed using a COOH5 sensor chip functionalized with VP1 protein. The sensorgram record showed a significant difference between positive and negative serum samples, which was confirmed by analysis of variation of initial and final dissociation values through time (ΔRUd/t). The data gathered here are unequivocal evidence that the SPR-HAVP1 strategy can be applied to detect IgM antibodies in human serum positive to the HAV. This is a new tool to be explored to diagnose human HAV infections.

Prevalence of hepatitis A in the capitals of the States of North, Southeast and South regions of Brazil: decrease in prevalence and some consequences.

Hepatitis A virus (HAV) infection has been considered one of the leading causes of acute hepatitis. The aim of the present study was to estimate the prevalence of HAV among children and adolescents in a population-based study in the capitals of the States of the North, Southeast and South of Brazil and identify predictive factors for the infection. A multi-stage sampling was used to select subjects aged between 5-9 and 10-19 years. Individual and household levels aside from the level of variables in the areas were collected. The outcome was the total IgG antibodies to HAV levels detected using a commercial Enzyme Immuno Assay (EIA). The associations between HAV and the independent variables were assessed using the odds ratio. A multilevel analysis was performed by GLLAMM using the Stata software. The prevalence of HAV infection in the 5-9 and 10-19 age groups was 28.7% and 67.5%, respectively for the North, 20.6% and 37.7%, for the Southeast and 18.9% and 34.5% for the South Region. The prevalence of HAV increased according to age in all sites. Variables related to education at the individual level (North and South), family and area level (South and Southeast) and family income level (Southeast and South) were independently associated with HAV infection. This emphasizes the need for individualized strategies to prevent the infection.

Hepatitis A antibody persistence 8 and 10 years after 1-dose and 2-dose vaccination in children from Panama.

BACKGROUND: Hepatitis A virus (HAV) remains a global public health concern, which is potentially growing in Latin America, due to an expected shift from high to intermediate endemicity levels. The use of HAV vaccines in pediatric national immunization programs (NIPs), either as a 2-dose or a 1-dose schedule, has been explored in Latin American countries; however, evidence demonstrating long-term protection in this population is limited in the region. We evaluated long-term antibody persistence following a 1-dose partial series and the recommended 2-dose schedule used in Panama's pediatric NIP. METHODS: Two independent cross-sectional serological surveys were conducted at year 8 (Y8) and Y10 following vaccination under the NIP with 1 or 2 doses of an inactivated HAV vaccine (Havrix, GSK). Seropositivity (anti-HAV antibody concentration ≥ 15 mIU/mL) rates and antibody geometric mean concentrations (GMCs) were assessed at each serosurvey. Non-inferiority of 1 dose versus 2 doses was also explored. RESULTS: This study (NCT02712359) included 600 and 599 children at Y8 and Y10 post-vaccination, respectively. Seropositivity rates were 74.3% (95% confidence interval [CI]: 69.0; 79.2) and 97.7% (95% CI: 95.3; 99.1) at Y8 and 71.9% (95% CI: 66.4; 76.9) and 96.3% (95% CI: 93.5; 98.2) at Y10, in the 1-dose and 2-dose groups, respectively. Antibody GMCs were lower in the 1-dose versus the 2-dose group in both surveys. Non-inferiority was not demonstrated since the lower limit of the 2-sided 95% CI for the between-group difference in seropositivity rates (1-dose minus 2-dose) was < -10%. CONCLUSION: Anti-HAV antibody persistence was observed in lower percentages of children receiving 1 dose versus 2 doses of Havrix, at 8 and 10 years post-vaccination in Panama. Further investigations are needed to confirm antibody persistence and conclude on the protection afforded beyond 10 years in the pediatric population in Latin America.

High prevalence of hepatitis A in indigenous population in north Brazil.

OBJECTIVES: Little is known about hepatitis A virus (HAV) prevalence in indigenous communities. This study aims to evaluate the prevalence of HAV in indigenous community compared to urban population located at Western Amazon in Brazil. RESULTS: A total of 872 serum samples were obtained from 491 indigenous and 381 non indigenous individuals aging 0 to 90 years. Samples were tested for total and IgM anti-HAV and positive IgM samples were tested for HAV RNA. The overall prevalence of total anti-HAV was 87%, increased according age showing 100% of prevalence in those aging more than 30 years (p < 0.0001) and it was similar among indigenous and urban population. Total anti-HAV prevalence varied between tribes (p < 0.0001) and urban sites (p = 0.0014) and spatial distribution showed high prevalence in homes that received up to 100 dollars. IgM anti-HAV prevalence was 1.7% with predominance in males, those aging more than 41 years. No HAV RNA was detected. In conclusion, high overall anti-HAV prevalence was found in indigenous communities in North Brazil demonstrating the importance of universal vaccination in this group.

Statistical modeling alongside observational data predicts long-term immunogenicity of one dose and two doses of pediatric hepatitis A vaccine in the Mendoza province of Argentina.

BACKGROUND: Follow-up for anti-hepatitis A (HA) antibody persistence up to 10 years was conducted after implementation of universal vaccination against HA virus (HAV) in Mendoza, Argentina. Based on these data, statistical modeling was used to predict the antibody persistence to 30 years. METHODS: A non-interventional study evaluated long-term immunogenicity (geometric mean concentrations [GMCs] and seroprotection rate) following routine vaccination with 1 dose (Group 1: N = 436) or 2 doses (Group 2: N = 108) of HA vaccine. Associated statistical modeling based on a Bayesian approach of mixed effects models on log transformed titers evaluated three models (linear, piecewise linear, and exponential decay, with and without a natural boosting effect). RESULTS: From the initial cohort, 9 participants (Group 1) and 1 participant (Group 2) showed antibody titers below the seroprotective threshold and received a booster. At Year 10, 190 (Group 1) and 51 (Group 2) participants remained in the study without a booster dose and all were seroprotected. Regarding statistical modeling, the piecewise linear model showed the best fit and demonstrated high and similar seroprotection for each schedule up to 30 years (89% [1-dose schedule], 85% [2-dose schedule]). The 2-dose schedule showed higher GMC (95% CI) than the 1-dose schedule (Year 10: 352 [271-456] versus 78 [69.8-87.6] mIU/mL) and Year 30 (predicted) (37 [13-97] versus 19 [11-34] mIU/mL). Natural boosting had little impact on predicted seroprotection rates at 30 years for the 1-dose schedule (89% [0.8-0.96] and 84% [0.73-0.94] with and without a natural booster, respectively). CONCLUSIONS: Long-term persistence of anti-HAV antibodies was observed up to 10 years with 1-dose and 2-dose vaccine schedules, supporting booster flexibility. Statistical modeling predicted good persistence of seroprotection for each schedule up to 30 years. Natural boosting had a limited impact on seroprotection rate predictions, enabling extrapolation of these results to non-endemic settings for traveler vaccination.

Serological and molecular study of Hepatitis E virus in pediatric patients in Mexico.

INTRODUCTION AND OBJECTIVES: Cases of viral hepatitis reported in Mexico are typically identified as hepatitis A, B and C. However, unspecified cases are reported annually. Hepatitis E virus (HEV) is an emergent agent that causes a self-limiting infection that can evolve to chronic in immunosuppressed individuals. In Mexico, HEV genotype 2 is considered endemic, though it's the prevalence is not well known. Therefore, the present study was designed to determine the prevalence of HEV among patients at the "Hospital Infantil de Mexico Federico Gomez". MATERIALS AND METHODS: The study included 99 patients, anti-HEV antibody (IgG and IgM) were detected by indirect ELISA and viral genome was identified using RT-PCR technique. Two PCR products of positive cases were sequenced. RESULTS: ELISA results were positive in 3% and 6%, for IgG and IgM respectively, 54.5% prevalence was found by PCR. Low lymphocyte count (p<0.05) and malnutrition (p<0.005) were significant factors for high PCR prevalence and could increase the possibility of infection. Two samples were sequenced and confirmed the presence of HEV genotype 3. CONCLUSIONS: This report reveals the incidence of HEV in pediatric patients in Mexico. Moreover, the identification of HEV genotype 3 in human samples suggests a potential zoonotic risk that requires further research.