anti-HAV Antibodies Research Articles

Significant Reduction in Seroprevalence of Antibodies Against Hepatitis A across Thailand, 2024.

Hepatitis A virus (HAV) is an RNA virus that causes acute hepatitis and is transmitted via the fecal-oral route. It has historically been highly endemic in Thailand, where most children develop lifelong immunity after infection. Economic development and improved sanitation have reduced HAV transmission, but immunity levels have declined, raising concerns about potential future outbreaks. This study aims to assess the seroprevalence of HAV antibodies in Thailand in 2024, 10 years after the last national survey in 2014, and to evaluate current immunity levels to inform public health strategies. A cross-sectional study was conducted in a population aged 6 months to 80 years across Thailand's geographic regions. A total of 4,312 serum samples were tested for anti-HAV antibodies using the chemiluminescent microparticle immunoassay. The seroprevalence data were compared with findings from previous surveys in 2004 and 2014. The study showed a significant decline in population immunity to HAV, with the age at which 50% of individuals had antibodies increasing from 36 in 2004 to 42 in 2014, and to 47 years in 2024. A majority of the population remained susceptible to HAV, particularly among younger age groups. Thailand has transitioned to low HAV endemicity, with a large proportion of the population lacking immunity. Despite the absence of significant outbreaks in recent decades, the risk of future outbreaks remains, particularly from imported cases. Enhanced surveillance and vaccination strategies are necessary to prevent future HAV transmission and manage public health risks.

Evaluation of hepatitis A virus recombinant proteins for detecting anti-HAV IgM and IgG antibodies.

Hepatitis A was highly endemic in India earlier. With recent developments, there is a shift in the endemicity to intermediate levels. This has resulted in the occurrence of hepatitis outbreaks with symptomatic infections in adolescents and adults. Occasionally, the disease manifestations are serious, leading to acute liver failure. In such a situation, there is a need for a timely diagnosis of the infection.

Age-stratified prevalence of anti-hepatitis A virus antibodies in four metropolitan Indian cities and recent changes in Pune city.

Pune, western India, was earlier identified as hyperendemic for hepatitis A. Subsequently, we noted age and socio-economic status-dependent reduction in hepatitis A virus (HAV) prevalence. To assess the situation in different parts of India, this multicentric, hospital-based, cross-sectional study was conducted in four metropolitan cities in the northern/southern/eastern/western regions. As per age group-anti-HAV-positivity-specific sample size calculations (1-40years), 496 samples/centre were collected from Pune, Kolkata, Chennai and Ludhiana. All samples were tested for anti-HAV antibodies using enzyme-linked immunosorbent assay (ELISA). Overall, 44.9% of children up to fiveyears of age were anti-HAV antibody-positive (ELISA), with a steady increase reaching 92.9% by the age of 26-40years. Importantly, 782/1756 (44.5%) of the total population ≤ 15years was anti-HAV negative and hence susceptible to HAV. The city-wise analysis documented similar patterns with afew differences. According to theWorld Health Organization (WHO) classification of HAV endemicity, Pune, Chennai and Ludhiana were classified as cities with intermediate endemicity, whereas Kolkata with lower seroprevalence had low endemicity. Compared to the 2011-2012 survey anti-HAV positivity remained unchanged in the other cities except for the rise in Chennai. Apart from age, other risk factors varied in different cities. A comparison of socio-economic-dependent, age-stratified serosurveys conducted during 1982, 1992, 1998,2017 and 2022 in Pune documented the shift from high to intermediate endemicity in the population with high socio-economic status in 1998 and lower-middle socio-economic strata in 2017. The lowering of anti-HAV positivity reflects a definite improvement in sanitation and voluntary vaccination, but seems to have slowed down during recent years. Additional, well-defined efforts are necessary.

Seroprevalence of Hepatitis A virus infections among schoolchildren in Amran Governorate, Yemen

Hepatitis A virus (HAV) is the predominant cause of acute viral hepatitis worldwide; however, data on HAV prevalence among schoolchildren are limited. This study aimed to investigate HAV seroprevalence among schoolchildren in Amran governorate. This is a cross-sectional study that was carried out among 299 students between October 2023 and July 2024. The blood specimens were collected, and the anti-HAV antibody was detected by an enzyme-linked immunosorbent assay (ELISA) technique. Of 299 students screened, the seropositivity rate for HAV was 4 (1.3%). A higher rate of HAV was detected among male students 3 (1.6%), in the age group of 5–8 years 1 (11.1%), and in those whose parents had a secondary certificate 2 (2.3%). Moreover, a higher seroprevalence of HAV was observed among students who drank untreated water (1.6%) and those with a history of hepatitis A infection (6.7%). Additionally, this result revealed that children whose families had a history of HAV infection had the highest risk factors for HAV infection (OR = 8.9667), and those whose family members had an HAV infection (OR = 1.9029). To combat the HAV requires the implementation of preventive measures aimed at improving hygiene and sanitation, advocating widespread vaccination, and a rapid response to outbreaks of the virus.

A-258 Hepatitis A infections among patients suspected of acute hepatitis attended in Brazilian health services

Abstract Background Millions of people worldwide are infected with Hepatitis A Virus (HAV) annually - the leading widely spread causes of acute viral hepatitis in developing countries across all continents. Objective To evaluate the prevalence of anti-HAV antibodies; to determine HAV genotypes by nucleotide sequencing in patients suspected of acute hepatitis at public healthcare institutions; and to assess the association between this infection with age, gender, region, and other risk factors Methods Between October 2019 and May 2023, we analyzed 1,562 patients with more than 18 years old with clinical suspected acute hepatitis. Results Out of the 1,562 individuals, 1,244 were seropositive for Anti-HAV IgG, a median age of 45 years (IQR: 35 to 56) vs. 31 years (IQR: 25 to 39) in non-reactive individuals (p<0.001). A higher seropositivity was found in men compared to women (p=0.002). North region showed the highest seropositivity (p<0.001). There was also an association between poor sanitation conditions and seropositivity, such as lack of sewage collection and consumption of untreated water (p<0.001), as well as an association between heterosexual orientation and higher likelihood of seropositivity (p=0.015). In the logistic regression analysis for anti-HAV IgG seropositivity, age and male sex were significantly associated with seropositivity (OR = 1.09, 95% CI: 1.08 to 1.11, p<0.001; OR = 1.56, 95% CI: 1.16 to 2.11, p=0.004). North region showed a significant increase in the odds for seropositivity compared to all other regions. For anti-HAV IgM, out of the 1,562 individuals, 97 were seropositive, significantly higher in younger individuals [median age of 34 years (IQR: 28 to 40) vs. 42 years (IQR: 32 to 54) in non-reactive individuals (p<0.001)] and in males (p<0.001). South and Southeast regions had higher seropositivity (p<0.001). Non-heterosexual orientation and more than 2 sexual partners significantly correlated with seropositivity (p<0.001). In the logistic regression analysis for anti-HAV IgM, age showed an inverse association with seropositivity (OR = 0.96, 95% CI: 0.94 to 0.98, p<0.001), being more frequent in men (OR = 1.86, 95% CI: 1.11 to 3.21, p=0.021). Consumption of seafood was significantly associated with increased odds of seropositivity for anti-HAV IgM (OR = 2.26, 95% CI: 1.43 to 3.56, p<0.001). South and Southeast regions showed more IgM positive cases than North, Northeast and Midwest regions. Among the 1,562 cases, 35 complete (or almost complete) HAV genomes were successfully recovered from metagenomics sequencing data. These genomes range from 6,625 to 7,462 bp in length (89-100% completeness), sequences were fairly similar in pairwise nucleotide alignment, classified as genotype I.A, and displaying identities ranging from 94.7 to 99.7%. Conclusions Hepatitis A infection was found among 6.2% acute hepatitis cases attended in public services in Brazil while previous infections or vaccinated patients were found in 78.9% patients. While anti-HAV IgG positive patients where most frequent in the North region of Brazil, acute hepatitis A (IgM-positive) were more frequent in South and Southeast regions. Our results reinforce the need to implement vaccination against hepatitis A among individuals with more than 18 years in our country.

The Immunological and Epidemiological Effectiveness of Pediatric Single-Dose Vaccination against Hepatitis A 9 to 11 Years after Its Implementation in the Tyva Republic, the Russian Federation.

Since 2012, universal single-dose HAV vaccination in children aged 3 years and older has been implemented in the Tyva Republic, a region of the Russian Federation. The aim of this prospective non-interventional observational single-center study was to determine the immunological and epidemiological effectiveness of single-dose vaccination against hepatitis A 9 to 11 years after its implementation. The anti-HAV IgG antibodies were determined in two independent cohorts of children who were vaccinated with a single dose of monovalent pediatric inactivated vaccine (HAVRIX® 720 EU) in Tyva in 2012 and recruited 9 years (Year 9 Cohort) and 11 years (Year 11 Cohort) after immunization. The seroprotection rates defined as anti-HAV antibody concentrations ≥10 mIU/mL reached 99.4% (95% CI: 98.2-99.9% [501/504]) in the Year 9 Cohort, but decreased significantly to 75.4% (95% CI: 73.0-77.6% [1006/1335]) in the Year 11 Cohort (p < 0.0001). The anti-HAV geometric mean concentrations decreased from 1446.3 mIU/mL (95% CI: 1347.1-1545.4 mIU/mL) in the Year 9 Cohort to 282.6 mIU/mL (95% CI: 203.8-360.8, p < 0.0001) in the Year 11 Cohort. The HAV vaccination program resulted in zero rates of hepatitis A incidence in the Tyva Republic since 2016. However, the limited monitoring of HAV RNA in sewage and environmental samples demonstrated the ongoing circulation of both the regional epidemic strain of HAV genotype IA and another genotype IA strain imported recently from other parts of the Russian Federation, probably due to subclinical infections in non-vaccinated children under 3 years of age. Taken together, these data indicate the effectiveness of the single-dose HAV vaccination strategy but suggest the need to expand the vaccination program to include children aged 12 months and older to achieve maximum effectiveness.

Cellular immune response to a single dose of live attenuated hepatitis a virus vaccine in obese children and adolescents

Cellular immune response to a single dose of live attenuated hepatitis a virus vaccine in obese children and adolescents

Six-month Follow-up of Hepatitis A Antibodies in Newborn Infants in Diyarbakir Province and Its Region

Objective: In this study, we aimed to determine the frequency and persistence of maternally transmitted anti-HAV antibodies in healthy newborn infants of people living in Diyarbakır province, which is located in a high HAV endemicity area, and its neighbourhood. Material and Method: In our study, infants born between October 1999 and January 2000 in the Gynaecology and Obstetrics Clinic of Diyarbakır Dicle University and registered in the Department of Paediatrics were followed up for 12 months. Blood samples were collected from all babies at birth, third and sixth months. Results: A total of 112 healthy newborns were included in the study. Of the infants, 62 (55.3%) were boys and 50 (44.7%) were girls. Demographic and medical information was obtained from the parents. Seropositivity was 90.2% at birth, 87.5% at 1 month, 39.3% at 6 months and 28.6% at one year. Conclusion: It was emphasised that our region has a high endemicity for HAV and in order to reduce HAV infection, socioeconomic level should be increased, hygiene should be given importance and immunisation with vaccine should be performed when appropriate conditions are met.

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 in Adults: Experience from a Moroccan Hospital Center

Background: In children, hepatitis A virus infection is usually symptom-free and provides long-term immunity. However, in changing socio-economic environments, certain adults encounter infection risks, exposing them to symptomatic illness and complications. This study aims to outline the profile of adult hepatitis A patients. Methods: We conducted a retrospective study from 2017 to 2023, involving all patients aged over 14 years who presented with acute hepatitis and tested positive for anti-HAV antibodies. Demographic, laboratory and clinical data were analyzed. Results: The analysis involved 109 cases (mean age 21 +/- 6 years, 57.8% males). All patients were symptomatic. Among them, 71.6% presented with a pseudo-flu-like syndrome, 89% with jaundice, 50.5% with fever and 30.2% with gastrointestinal symptoms. Thirty patients were hospitalized (26.6%), among them one subfulminant was recorded. Clinically, hepatomegaly was found in 8 patients (7.3%). One patient had presented with a skin rash. Serum alanine aminotransferases levels were more than 50 times the normal range in 47.7% of cases, with an average bilirubin level of 89 mg/l. Severe acute hepatitis was observed in 26.6% of patients. Conclusion: Our findings revealed that over 25% of adult patients experienced severe acute hepatitis, with one patient progressing to acute liver failure. These results underline the importance of raising awareness of hygiene practices and prompt a study of the overall seroprevalence of hepatitis in the adult population in order to improve viral hepatitis prevention and control strategies in the country.

Prevalence of glucose-6-phosphate dehydrogenase (G6PD) deficiency among the fulminant hepatitis A virus infection patients.

Hepatitis A is a widespread viral infection with significant public health implications. Assessing glucose 6-phosphate dehydrogenase (G6PD) deficiency in hepatitis A patients is essential for various reasons, including prognosis, disease severity evaluation, encephalopathy risk identification, tailored management, and advancing scientific understanding. This study aimed to investigate the prevalence and clinical implications of G6PD impairment in individuals with fulminant hepatitis A. A cross-sectional descriptive analysis was conducted, involving hospitalized patients with fulminant hepatitis A. Demographic data, prevalence rates, and clinical findings were recorded in a database. The diagnosis of hepatitis A infection was confirmed using an anti-HAV IgM antibody test, and G6PD enzyme activity was measured with a fluorescent spot assay. Out of 81 patients with hepatitis A, 57 (70.4%) were males, and 24 (29.5%) were females, with an average age of 24.6 years. Dark yellow urine and anorexia were the most common clinical symptoms. Notably, 30 (37%) patients lacked G6PD. The group with G6PD deficiency showed significantly higher rates of encephalopathy and mortality (P<0.01), along with elevated bilirubin (P=0.00), abnormal coagulation parameters, and low hemoglobin levels (P=0.00). In light of these findings, the present study proposes the implementation of routine G6PD level assessments and the evaluation of other relevant markers in regions where hepatitis A is endemic. Furthermore, the study underscores the need for vigilant monitoring of hemolysis and encephalopathy in affected patients to optimize clinical management and reduce morbidity and mortality associated with this condition.

Seroprevalence of hepatitis A virus antibodies among children and adolescents living in Northern Thailand: an implication for hepatitis A immunization

This cross-sectional study aimed to assess seroprevalence of hepatitis A virus (HAV) antibodies and identify factors associated with HAV seropositivity among children and adolescents aged 1–18 years who resided in Chiang Mai, Thailand. Sociodemographic characteristics, sanitation/hygiene, and history of HAV vaccination were collected. Anti-HAV IgG antibody was determined, and a level ≥ 1.0 S/CO defined HAV seropositivity. We enrolled 300 participants; median age 8.7 years, 54% male, and 13% overweight (BMI z-score: + 1 to + 2 standard deviation [SD]). Sixty-five participants (22%) were vaccinated against HAV. Overall, 84/300 participants (28%) demonstrated HAV seropositivity, of whom 55/65 (85%) and 29/235 (12%) were among vaccinated and unvaccinated participants (P < 0.001), respectively. Previous HAV vaccination (adjusted odds ratio [aOR] 47.2; 95% CI 20.0–111.8) and overweight (aOR 4.4; 95% CI 1.7–11.3, compared with normal weight [BMI z-score: − 2 to + 1 SD]) were significantly associated with seropositivity of HAV. In the stratified analyses, crowded bedroom (aOR 3.2; 95% CI 1.3–7.8, per one person increase) and overweight (aOR 5.0; 95% CI 1.8–13.7) were factors associated with HAV seropositivity among vaccinated and unvaccinated participants, respectively. Seroprevalence of HAV antibodies in healthy Thai children and adolescents was relatively low. Recommendation of HAV vaccination for these populations, particularly those with high-risk conditions, should be considered.

Prevalence of Rotavirus, Adenovirus, and Hepatitis A Virus in a Tertiary Care Hospital in Somalia

Rotavirus, one of the viral infectious agents that is transmitted mainly through the fecal-oral route and spreads easily in regions with poor sanitation conditions, is the most common causative agent of acute gastroenteritis in children under five years of age worldwide, and enteric adenoviruses are other frequently encountered causative agents of gastroenteritis in childhood. Hepatitis A virus (HAV) is also transmitted in similar routes and is endemic in regions with poor sanitation conditions and limited access to clean water and is usually acquired in early childhood in these regions. In this study conducted in Mogadishu Somalia, rotavirus and adenovirus antigen test (immunochromatographic rapid test) results in patients admitted to a tertiary hospital in the 9-month period between February 2019 and October 2019 and ELISA based HAV antibody test results studied in 2018-2019 were retrospectively examined and it was aimed to determine the distribution of positivity rates of these viruses by age, gender, and year. During the study period, 1136 patients (mean age 6.33±12.36) were tested for rotavirus and adenovirus antigens, and 362 patients (mean age 21.26±18.45) were tested for anti-HAV IgM/IgG antibodies. The positivity rates of rotavirus and adenovirus were found as 17.8% and 5.1%, respectively. The positivity rates of anti-HAV IgM and IgG antibodies were 26.5% and 85.4%. The age group with the highest rotavirus test positivity was babies under one year old (27.3%), positivity rate was also high in children aged 1-2 years old (20.9%), and this distribution was similar for adenovirus. Although a small number of patients were tested in under five years of age, anti-HAV IgG seropositivity was 60% and above in all age groups. The highest anti-HAV IgM positivity rates were observed in children 2-&lt;5 and 5-15 years of age, 52.9% and 44% respectively. Rotavirus antigen positivity was found at high levels in the three-month period covering June, July, and August 2019. In July (2019), it was observed that the number of rotavirus and adenovirus antigen test requests were increased, and also, at the same time the highest positivity rates for both viruses were observed; 31.2% and 9.5% for rotavirus and adenovirus. Rotavirus and enteric adenovirus co-infection was detected in 2.4% (27/1136) of the patients, and 23 (85.2%) of these were under five years of age children. Our study results show that children under the age of two are especially affected by rotavirus and adenovirus infections in Somalia and indicate that HAV infections are acquired at an early childhood. We can say that it may be useful to review vaccination programs as an important public health measure to reduce the burden of mortality and morbidity associated with HAV and rotavirus, which have a high prevalence and also have protective vaccines.

Immunogenicity persistence of hepatitis A vaccines Healive® and Havrix® among children:15 years follow-up and long-term prediction

ABSTRACT Healive® was the only Chinese WHO-prequalified inactivated vaccine for the hepatitis A virus, which has been widely used in national immunization programs in China. Long-term follow-up studies are needed to estimate the persistence of vaccine-induced antibody levels and the necessity for booster vaccines. During the trial, geometric mean concentrations (GMCs) and seroconversion rates (SRs) of anti-HAV antibodies were compared based on two different inactivated hepatitis A vaccines, Healive® and Havrix®. Four hundred children were randomly assigned to receive two doses of Healive® or Havrix® at 0 and 6 months. The current study assessed antibody persistence for both vaccines 15 years post-immunization. A mixed linear model was used to predict long-term antibody persistence. The GMCs were significantly higher for Healive® compared to Havrix® at 1, 6, 7, 66, 138 months (P < .001) and 186 months (P = .004 < .05) post-vaccination. Healive® and Havrix® reached a GMC of 164.8 mIU/ml and 105.7 mIU/ml post-15 years of vaccination, respectively. The seroconversion rates of both vaccines showed no statistically significant differences (97.9% for Healive® and 94.7% for Havrix®, P = .20). The prediction showed that Healive® would provide protection for a minimum of 30 years following immunization, with a lower limit of the 95% confidence intervals for GMCs greater than 20mIU/mL. Compared to Havrix®, the vaccine Healive® showed a stronger protective effect and better persistence among children at 15 years post-full immunization. Prediction indicated at least 30 years of antibody persistence for Healive® and at least 25 years for Havrix®.

Sporadic Hepatitis A Virus PCR False-Positive Results Observed during Reflex Testing of Serum Samples Previously Tested for Anti-HAV Antibodies and Caused by Contamination with HAV RNA Present in the Reagents of the Commercial Anti-HAV Immunoassay.

Hepatitis A diagnosis relies on serology and occasionally on hepatitis A virus (HAV) RNA detection. For timely diagnosis and the avoidance of drawing additional blood, molecular testing is often performed as reflex testing by using blood specimens that were initially sent for anti-HAV serology. Reflex molecular testing is preferably performed from different sample aliquots, but, for limited sample quantities, it uses samples that have been preprocessed in an immunoassay analyzer. In 2012, we first observed sporadic HAV RNA-positive cases that were inconsistent with patients' serological profiles and/or medical histories, suggesting that occasional laboratory contamination was causing false-positive PCR results. Multiple external quality assurance (EQA) and laboratory surface contamination checks were performed, questionable specimens were tested with various HAV RNA tests, and follow-up serum/stool samples were collected. All contamination-check samples and samples from healthy individuals tested HAV RNA-negative, and the laboratory successfully passed all EQAs. The HAV RNA-positive results were reproducible with various HAV RNA assays. No patients seroconverted, and their follow-up samples were consistently HAV RNA-negative. Finally, a detailed review of testing protocols revealed a correlation between HAV RNA false positivity and preceding anti-HAV testing with the Cobas-e411 automated immunoassay analyzer. HAV RNA was detected in the Cobas-e411 anti-HAV reagents, with the HAV sequences matching those from the false-positive samples. Preceding anti-HAV testing using two other immunoassay analyzers did not result in subsequent HAV RNA false positivity during reflex testing. The Cobas-e411 pipetting procedure with a single pipette tip collecting samples and anti-HAV reagents contaminated the original sample with the HAV RNA that was present in the immunoassay's reagents, thereby resulting in HAV RNA false positivity during the reflex testing. IMPORTANCE We present the first report of sporadic HAV PCR false-positive results that have been observed during the reflex testing of serum samples that have previously been tested for anti-HAV antibodies and have been caused by contamination with HAV RNA that is present in the reagents of the commercial anti-HAV immunoassay, with potentially serious clinical consequences. Although HAV RNA was consistently detected in the anti-HAV reagents of all three automated immunoassay analyzers that were in use in our laboratory, only the use of one analyzer and the corresponding commercial anti-HAV immunoassay reagents resulted in contamination that led to false positive HAV RNA results, and this was due to a peculiar pipetting mode of action in which the analyzer uses a single pipette tip to collect both anti-HAV reagents and a sample, which consequently causes the permanent contamination of the original sample with HAV RNA. Manufacturers should strongly consider the occasional need for reflex molecular testing from preprocessed samples and design their analyzers in a way that prevents contamination.

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.

A randomized clinical trial of one-dose versus accelerated two-dose schedule for hepatitis A virus revaccination among people with HIV who were non-responders or had seroreversion after primary HAV vaccination.

For people with HIV (PWH) who have no serological responses to their primary hepatitis A virus (HAV) vaccination or have seroreversion after successful primary vaccination, optimal revaccination strategy remains unclear. In this open-label, randomized clinical trial, PWH who tested negative for anti-HAV antibodies after receiving a standard 2-dose series of primary HAV vaccination were enrolled and assigned in a 1:1 ratio to receive either one dose (the one-dose group) or two doses of HAV vaccine administered four weeks apart (the two-dose group). Serological response rates and the anti-HAV antibody titers at weeks 24 and 48 were compared. Of the 153 participants (77 in the one-dose group and 76 the two-dose group), the overall serological response rates at week 48 after revaccination were not statistically significantly different between the two groups (two- vs. one-dose, 80.2% vs. 71.4%, p=0.20). However, anti-HAV antibody titers were consistently higher in the two-dose group than the one-dose group. In subgroup analysis, PWH who were non-responders to their primary HAV vaccination were significantly more likely to mount a serological response after two-dose HAV revaccination (68.4% vs. 44.1%, p=0.038). No severe adverse effects were reported throughout the study. Two-doses HAV revaccination administered four weeks apart yielded similar serological responses as one-dose revaccination among PWH who were non-responders or had seroreversion after primary HAV vaccination. Two-dose revaccination schedule generated significantly higher anti-HAV antibody titers and were more likely to elicit serological responses at week 48 among PWH who were non-responders to primary HAV vaccination.

Assessment of herd immunity to hepatitis A virus among the population of the Republic of Tatarstan

Introduction. Identification of the groups of the population most susceptible to infection with hepatitis A virus (HAV) is a key component for the regulation of anti-epidemic measures during the activation of the epidemic process. The aim аssessment of the herd immunity to hepatitis A (HA) among different age groups of the population of the Republic of Tatarstan. Materials and methods. The analysis of the HA incidence of from 2006 to 2021 and the study of herd immunity to HA among 6,553 persons from different age groups that were not vaccinated against HA were carried out. Participants with protective concentrations of antibodies to HAV of 20 mMU/ml or more were considered as seropositive. Results. The analysis showed a low intensity of the epidemic process in general (3.6 0.3о/оооо), while the HA incidence among children and adults was significantly different, with incidence rates 2.3 times higher in the first group (6.9 0.9 and 3.0 0.3о/оооо, respectively). The epidemic process is determined by persons aged 1517 years (8.2 2.5о/оооо), 36 years (7.0 1.9о/оооо, 714 years (6.2 1.3о/оооо), the incidence among these age groups in all observed years remained the highest. In general, the proportion of seropositive children was 32.1 1.0%. Among adults, anti-HAV IgG antibodies in a protective concentration was detected in 68.2 0.7%. The highest frequency of anti-HAV IgG positive samples was observed among persons aged 5059 years 89.4 1.1%, in age group 4049 years 73.5 1.2%, in age group 3039 years 65.5 1.3%, and in age group 2029 years 48.2 1.6%. In total, 56.9 0.6% of the examined individuals had protective antibodies to HAV. The detection rates of anti-HAV IgG antibodies were significantly different in all age groups (p 0.05).

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.

Prevalence of HIV and Viral Hepatitis Markers among Healthcare Workers in the Republic of Guinea.

Healthcare workers are much more likely to be infected with HIV and hepatitis viruses compared to the general population. Although healthcare workers are more aware of HIV and hepatitis viruses, several countries in Africa lack a comprehensive grasp of disease routes and transmission risks. The aim of this study was to assess the prevalence of the serological and molecular biological markers of HIV and viral hepatitis among healthcare workers in the Republic of Guinea. The study material was 74 blood serum samples collected from healthcare workers who received additional training at the Institute of Applied Biological Research of Guinea (IRBAG, Kindia, Republic of Guinea). The markers examined included HBsAg, HBeAg, anti-HBs IgG, anti-HBcore IgG, anti-HCV qualitative determination, anti-HEV IgM and IgG, anti-HAV IgM and IgG, and anti-HIV. For viral DNA and RNA detection, nucleic acids were extracted from blood serum, and viral presence was inferred using real-time PCR with hybridization fluorescence detection. A high prevalence of viral hepatitis B markers was shown, and significantly fewer cases of viral hepatitis C and HIV were detected. Almost all examined medical workers had anti-HAV IgG antibodies, but no antibodies to hepatitis E virus. Apparently, the identified markers depend on the general prevalence of certain pathogens in the region and are associated with the traditions and characteristics of the country's residents.