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.

Molecular characterisation of hepatitis A in the Western Cape province, South Africa in 2023.

In 2023, passive laboratory-based surveillance showed an increase in hepatitis A virus (HAV) infection. We investigated hepatitis A incidence using the notifiable medical condition surveillance system (NMCSS) data and molecularly characterised positive blood samples from the Western Cape province for 2023. All HAV IgM seropositive cases from the NMCSS from 1 January to 31 October 2023 in South Africa were investigated. HAV RNA from blood samples that had tested positive for HAV IgM from Western Cape was amplified in the VP1/P2B junction and sequenced (3500Xl Genetic Analyser). Sequences were assembled, aligned (Sequencher) and analysed (Aliview 1.27 and MEGA11). Statistical analysis was performed using Excel and the CuSum2 Threshold to determine suspected outbreaks. In 2023, the incidence of HAV IgM was 6.28/100,000 in South Africa, with the highest incidence in Western Cape province (15.86/100,000). Children aged 5 to 14 years were affected the most in the Western Cape. The positive cases in the Western Cape were above the CuSum2 threshold from January to May 2023, with the highest incidence observed in the City of Cape Town Metropolitan (14.8/100,000). Genotyping was successfully performed on 92.7% (139/150) of serum samples, for which the IB sub-genotype was detected. Three primary mutations R63K, R71S and M104I were observed in more than 49% of the samples. Most of the samples sequenced belonged to patients residing in areas close to each other within the City of Cape Town Southern, Western, and Mitchells Plain sub-districts. The CuSum2 threshold method allowed the identification of suspected HAV outbreaks in the districts within the Western Cape in 2023 while genotyping identified clusters of sub-genotype IB. Genotyping could assist with determining the common source of infection during an outbreak, especially if coupled with epidemiological and geographical data. Further active surveillance can assist in investigating the HAV risk factors for targeted public health responses.

Seroprevalence of hepatitis A virus infection in Central-West of Tunisia.

Hepatitis A infections still represent a major global health concern. During the past years, a transition pattern of the hepatitis A epidemiology was noted in many parts of the world. In Tunisia, there is not a recent survey on age-specific hepatitis A virus seroprevalence. This study aimed to investigate the seroprevalence of hepatitis A virus infection in Central-West Tunisia, representative of regions with lowest socioeconomic level in the country, before vaccine implementation. Sera obtained from the blood samples of subjects were screened for the detection of hepatitis A virus. The seroprevalence was evaluated by detection of total antibodies to hepatitis A virus using commercially available immunoassay kits. A total of 1379 subjects, aged 5-75 years (mean age: 29.0 ± 17.3 years) were studied. The global anti-hepatitis A virus seroplevalence was 84.7% (95% confidence interval: [82.6-86.5]). A higher hepatitis A virus seroprevalence was showed in subjects aged 10-14 years compared to those aged less than 10 years (50.0% vs. 31.0%). In subjects aged 20-29 years, a rapid increase in the hepatitis A virus prevalence was noted; it reached 97.0%. The seroprevalence of anti-hepatitis A virus differed by zone of residence (81.1% in rural area vs. 72.4% in urban area, p = .005) and increased significantly with lower level of education (p = .019). There was no statistical significant seroprevalence difference between male and female: 84.2% versus 85.2%, respectively. Our study confirm the transition pattern of the hepatitis A virus endemicity in Tunisia from high to intermediate and provide an evaluation of the hepatitis A virus epidemiological situation before vaccine implementation.

Hepatitis A vaccine immunogenicity 25 years after vaccination in Alaska.

The hepatitis A vaccine is recommended for all children greater than or equal to 1 year of age, however, the duration of vaccine protection is unknown and protection through adulthood is crucial to prevent symptomatic hepatitis later in life. We report on 25 years of follow-up of a cohort of Alaska Native individuals who were vaccinated in early childhood. We assessed the duration of vaccine protection by calculating the geometric mean concentration and proportion of participants with protective levels of IgG antibody to hepatitis A virus (anti-HAV) (≥20 mIU/mL) every 2 to 3 years. We estimated the amount of time until the anti-HAV dropped below protective levels using survival analyses. At 25 years, 43 of the original 144 participants were available, mean anti-HAV levels were 91.5 mIU/mL, and 35 (81.4%) had protective levels of anti-HAV. Using data from all persons and all time points, a survival analysis estimated 78.7% of participants had protective levels of anti-HAV at 25 years. The high level of protective antibodies in this cohort indicate that supplemental doses of hepatitis A vaccine are not needed 25 years after completion of the vaccine series.

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.

Immunity to hepatitis A among men who have sex with men attending a large sexual health clinic in Melbourne, Australia, 2012-2018.

BACKGROUND: Outbreaks of hepatitis A are being reported more commonly among men who have sex with men (MSM) globally. Australia has also reported a sharp increase in the number of cases of hepatitis A in 2017. This study aimed to determine the level of immunity to hepatitis A among MSM attending a large urban sexual health clinic in Victoria in the lead up to recent outbreak. METHODS: This was a retrospective audit of serological testing data from first-time MSM attendees at Melbourne Sexual Health Centre (MSHC) in Australia from 1 January 2012 to 31 December 2018. We determined the proportion of MSM who were tested and who had serological detection of hepatitis A IgG, stratified by age and calendar year. We used univariable and multivariable logistic regression to investigate factors associated with testing for and detection of hepatitis A IgG. RESULTS: There were 16 609 first-time MSM attendees at MSHC over the 7-year period, of which 9718 (59%, 95% CI 58% to 60%) were tested for hepatitis A IgG. There was a 2% annual increase in the proportion of men tested (from 60% in 2012 to 69% in 2018; OR=1.02, 95% CI 1.00 to 1.03, p=0.025). Men born outside of Australia/New Zealand, and younger men <30 years had higher odds of being tested. Of those tested, 44% (n=4304, 95% CI 43% to 45%) had hepatitis A IgG detected at their first visit, with no change over time (OR=1.01, 95% CI 0.99 to 1.03, p=0.210). Detection of hepatitis A IgG was associated with being aged 30 years or older (adjusted OR=2.06, 95% CI 1.89 to 2.24, p<0.001) or being born overseas versus Australia/New Zealand (AOR=1.21, 95% CI 1.11 to 1.31, p<0.001). CONCLUSION: Hepatitis A immunity among MSM remains below the estimated 70% required to prevent outbreaks. Measures including increased testing and higher vaccination coverage are needed to prevent outbreaks and to limit the number of cases and deaths.

Hepatitis a virus infection in Central-West Tunisia: an age structured model of transmission and vaccination impact.

BACKGROUND: The epidemiological pattern of hepatitis A infection has shown dynamic changes in many parts of the world due to improved socio-economic conditions and the accumulation of seronegative subjects, which leads to possible outbreaks and increased morbidity rate. In Tunisia, the epidemiological status of hepatits A virus is currently unknown. However, over the past years higher numbers of symptomatic hepatitis A virus infection in school attendants and several outbreaks were reported to the Ministry of Health, especially from regions with the lowest socio-economic levels in the country. The aim of this study was to investigate the current seroprevalence of hepatitis A virus antibodies in central-west Tunisia and assess the impact of hepatitis A virus vaccination on hepatitis A epidemiology. METHODS: Serum samples from 1379 individuals, aged 5-75 years, were screened for hepatitis A virus antibodies. Adjusted seroprevalence, incidence and force of infection parameters were estimated by a linear age structured SEIR (Susceptible-Exposed-Infectious-Recovered) compartmental model. A vaccine model was then constructed to assess the impact on hepatitis A virus epidemiology of 3 scenarios of vaccination strategies: one dose at 12-months of age, one dose at 6-years and one dose at 12-months and another at 6-years of age during 6 years. RESULTS: A rapid increase in anti-hepatitis A virus seroprevalence was noted during infancy and adolescence: 47% of subjects under 10-years-old are infected; the prevalence increases to 77% at 15-years and reaches 97% in subjects aged 30-years. The force of infection is highest between 10 and 30-years of age and the incidence declines with increasing age. The vaccine model showed that the 3-scenarios lead to a significant reduction of the fraction of susceptibles. The two doses scenario gives the best results. Single-dose vaccination at 6-years of age provides more rapid decrease of disease burden in school-aged children, as compared to single-dose vaccination at 12-months, but keeps with a non-negligible fraction of susceptibles among children < 6-years. CONCLUSIONS: Our study confirms the epidemiological switch from high to intermediate endemicity of hepatitis A virus in Tunisia and provides models that may help undertake best decisions in terms of vaccinations strategies.

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.

Prevalence of clinically significant antibodies in patients undergoing elective surgery in a Nigerian teaching hospital: A case for the type and screen method.

BACKGROUND: Provision of safe and adequate blood is challenging in our environment due to paucity of voluntary donors as well as inappropriate blood ordering and utilization. The type and screen (TS) method (typing of blood group and screening for antibodies) reduces the demand for blood reservation in hospital blood banks. AIMS: The aim of this study is to determine the safety (detection clinically significant antibodies) and cost effectiveness of the TS method compared to the conventional antiglobulin crossmatch (ACM). SETTINGS AND DESIGN AND METHODS: This was a cross-sectional prospective study carried out at the University of Port Harcourt Teaching Hospital (UPTH). 124 participants booked for elective surgeries with no history of blood transfusion or pregnancy were investigated. ACM was performed on all participants' serum against 159 donor red cells. TS was also performed blindly on the same participants' sera, antibody screening was done with three-screen-cells using the gel method. An 11-cell panel was used for antibody identification. Blood utilization was calculated using the crossmatch: transfusion ratio (CTR), probability of transfusion (%T) and transfusion index (TI). RESULTS: Out of the 159 units crossmatched for 124 study participants, only 19 were actually transfused (88.1% not utilized). The prevalence of compatible ACM was 100%, however the TS detected one antibody (0.81%) in a male participant identified as anti-M. The overall CTR, %T and TI were 8.4, 15.6% and 0.16 respectively, with N384,750 ($963.1) wastage in terms of cost. The TS method would have saved N266,000{$665.9} (N1900{4.78} per un-transfused patient). CONCLUSIONS: There was improper utilization of blood in elective surgeries. The TS method identified an antibody not detected by ACM. This would have saved N266,000 {$665.9}, and reduced the demand for blood reservation in the bank. Although The TS method was found not to be significantly different in outcome compared to the ACM, it was found to be cost effective.

Herd Immunity Likely Protected the Men Who Have Sex With Men in the Recent Hepatitis A Outbreak in San Diego, California.

A high seroprevalence of hepatitis A virus (81%) among human immunodeficiency virus-negative high-risk men who have sex with men is likely why this community was largely spared from a recent hepatitis A virus outbreak in San Diego, California.

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.

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%.

A systematic review of the epidemiology of hepatitis A in Africa.

BACKGROUND: Hepatitis A, caused by the hepatitis A virus (HAV), is a vaccine preventable disease. In Low and Middle-Income Countries (LMICs), poor hygiene and sanitation conditions are the main risk factors contributing to HAV infection. There have been, however, notable improvements in hygiene and sanitation conditions in many LMICs. As a result, there are studies showing a possible transition of some LMICs from high to intermediate HAV endemicity. The World Health Organization (WHO) recommends that countries should routinely collect, analyse and review local factors (including disease burden) to guide the development of hepatitis A vaccination programs. Up-to-date information on hepatitis A burden is, therefore, critical in aiding the development of country-specific recommendations on hepatitis A vaccination. METHODS: We conducted a systematic review to present an up-to-date, comprehensive synthesis of hepatitis A epidemiological data in Africa. RESULTS: The main results of this review include: 1) the reported HAV seroprevalence data suggests that Africa, as a whole, should not be considered as a high HAV endemic region; 2) the IgM anti-HAV seroprevalence data showed similar risk of acute hepatitis A infection among all age-groups; 3) South Africa could be experiencing a possible transition from high to intermediate HAV endemicity. The results of this review should be interpreted with caution as the reported data represents research work with significant sociocultural, economic and environmental diversity from 13 out of 54 African countries. CONCLUSIONS: Our findings show that priority should be given to collecting HAV seroprevalence data and re-assessing the current hepatitis A control strategies in Africa to prevent future disease outbreaks.

Sero-prevalence of viral hepatitis A in a district of Sri Lanka: a community based cross-sectional study.

BACKGROUND: Hepatitis A Virus (HAV) is one of the most common food and water borne infectious disease prevailing globally. The objective of the study was to determine sero-prevalence of HAV infection in a district of Sri Lanka. METHODS: This was a descriptive cross sectional study conducted on 1403 participants aged 1 year and above selected by multistage stratified (for age group and area of residence) cluster sampling from September 2015 to December, 2016. An interviewer-administered questionnaire was used to collect data and Anti-IgG testing was done to determine sero-positivity. The overall, the age and sex specific sero-prevalence of HAV were calculated with 95% confidence intervals (CI). RESULTS: Of the 1403 participants 1132 were anti HAV IgG positive. Therefore the overall sero-prevalence of HAV infection was 80.7% (95%CI: 78.64-82.76). There were 283 (20.2%) individuals below the age group of 14 years and below and out of them, 204 had anti HAV IgG, therefore sero-prevalence was 72.1% for that age group. The age group 15 years and aboe comprised of 1120 (79.8%) participants and of them 928 had anti HAV IgG, making sero-prevalence 82.9%. The lowest sero-prevalence (66.9%, n = 232) was observed in the age group of 11-20 years followed by 21-30 age group. From age 31 years onwards, the sero-prevalence exceeded 90%, reaching 100% after 71 years. The urban population showed a sero-prevalence of 83% (n = 195) and 80.2% (n = 937) for the rural sector while females had a sero-prevalence of 82.2% (n = 766) and it was 77.7% (n = 366) for males. Thirty-four (3.0%) participants who had sero-positive results (n = 1132) claimed that they have had HAV in the past. CONCLUSIONS: Overall, four fifth of the population was immune to HAV infection in the district of Gampaha.

Suspected spread of hepatitis A virus from a restaurant among adults in rural area of the Kerala state, India.

India is experiencing a substantial decrease in early childhood exposure to hepatitis A virus (HAV). Kerala has experienced several hepatitis A outbreaks in young adults/adults in the recent past. The current hepatitis outbreak occurred in Nellikuzhi, Kerala state, India in December 2016. Investigation was carried by preparing a line list of suspected hepatitis cases. The blood and stool samples collected from patients were tested for anti-HAV/anti-Hepatitis E virus (HEV) immunoglobulin (IgM) antibodies and RNA respectively. A total of 562 suspected hepatitis cases were reported during the outbreak. Along with the first case (35 years, male), 86.1% (484/562) of the cases gave history of consuming food/water/cold drinks from one restaurant. Anti-HAV IgM positivity was 74.5% (73/98) in tested samples and amongst the positives, 81% were adults/young adults and adolescents. None of the samples tested positive for anti-HEV IgM. There were three HAV associated deaths without any co-morbidity. Sequence analysis of HAV RNA positive stool samples showed the presence of genotype IIIA HAV. The suspected source of the infection was a private well situated in the premise of a restaurant. Considering increasing HAV naive population in Kerala, there is a need to introduce hepatitis A vaccine in high-risk age groups.

Perspectives on Acute Hepatitis A Control in Korea.

Until 1995, the incidence of symptomatic acute hepatitis A was minimal and there were no cases of national outbreak in Korea. However, there was a nationwide outbreak of hepatitis A that peaked in 2009. In 2019, a total of 10,083 cases of acute hepatitis A were reported for seven months of the year according to the Korea Center for Disease Control and Prevention. This may be attributed to the proportion of susceptible subjects in the Korean population, as about 10 years have passed since herd immunity was induced by the epidemic occurring during the late 2000s. Recent studies have shown that the rate of seropositivity for anti-hepatitis A virus antibodies (anti-HAV) is the lowest in adults in their 20s and has not changed much over the past 10 years, and seropositivity of anti-HAV in adults in their 30s has continued to decline from 69.6% in 2005 to 32.4% in 2014. Most young adults who have not yet experienced hepatitis A and are not vaccinated are vulnerable to hepatitis A infection. This year's epidemic of hepatitis A is a predictable outcome for vulnerable populations. Therefore, effective acute hepatitis A control and prevention strategies are needed, particularly for those in their 20s and 30s.

Hepatitis A vaccine immune response 22 years after vaccination.

In the United States, the incidence of hepatitis A virus (HAV) infection has been reduced through universal childhood vaccination. However, the duration of immunogenicity for the hepatitis A vaccine is not known. We report on the 22 year follow-up time point of a cohort of Alaska children who were randomized to three different vaccine schedules: A) 0, 1, and 2 months; B) 0, 1, and 6 months; and C) 0, 1, and 12 months. Among 46 participant available for follow-up, 40 (87%) maintained protective levels of anti-hepatitis A antibody. These results indicate that a supplemental booster dose is not yet necessary at or before the 22-year time point.

Distribution of hepatitis A antibodies in US blood donors.

BACKGROUND: Recently, there has been an increase in the number of hepatitis A outbreaks in the United States. Although the presence of hepatitis A virus (HAV) RNA in blood donors is known to be low, HAV antibody prevalence in this population is unknown. STUDY DESIGN AND METHODS: Samples from 5001 US blood donors collected primarily in the midwestern United States in 2015 were tested for the presence of HAV IgG antibodies using chemiluminescent microparticle immunoassays on the ARCHITECT platform (Abbott Laboratories). RESULTS: The overall prevalence of IgG anti-HAV was 60%. Only one specimen was IgM anti-HAV positive, for an incidence of 0.02%. IgG anti-HAV prevalence among donors aged 16 to 19 years was 67%, decreased to 54% among donors aged 40 to 49 years and increased to 70% among donors aged 80 to 93 years. No differences were seen by sex with overall IgG anti-HAV prevalence of 61% and 60% for males and females, respectively. Among the five states (Illinois, Indiana, Kansas, Kentucky, and Missouri) with the highest number of donors tested, IgG anti-HAV prevalence in Missouri (65%) was significantly higher (p <0.01) than that in Illinois (52%) or Kentucky (59%). No other significant differences between states were noted. CONCLUSION: This study demonstrates the overall high rates of IgG anti-HAV in US blood donors, with the low associated risk of HAV transfusion transmission likely the result of low incidence and effective vaccination.

Serological responses to revaccination with hepatitis A virus (HAV) vaccines among HIV-positive individuals whose anti-HAV antibody waned after primary vaccination.

BACKGROUND: Among HIV-positive individuals, seroprotection for hepatitis A virus (HAV) following primary vaccination may wane with time. However, seroresponses to HAV revaccination are rarely investigated among HIV-positive patients who have lost protective antibodies after primary vaccination. METHODS: During the outbreak of acute hepatitis A in Taiwan after June 2015, HAV-seronegative, HIV-positive individuals were advised to receive two doses of HAV vaccines at 24 weeks apart. A retrospective 1:2 matched case-control study was conducted to compare the seroresponses at weeks 4, 24, 28 and 48 of HAV vaccination between those who underwent revaccination after having lost protective antibodies (case patients) and those who underwent primary vaccination (controls). RESULTS: Seventy-five case patients and 150 matched controls were included. The serological response rates were consistently higher among the case patients than controls: 88.1% vs 10.5% at week 4 following the first dose of HAV vaccination (P < .001); 93.3% vs 46.0% at week 24 (immediately before the second dose; P < .001); 98.7% vs 62.7% at week 28 (4 weeks after the second dose; P < .001) and 98.7% vs 92.7% at week 48 (P = .06). The anti-HAV antibody titres as reflected by the semi-quantitative assay for the case patients were also significantly higher than the controls at weeks 24, 28 and 48 following HAV vaccination. CONCLUSIONS: We demonstrated faster and better serological responses to HAV revaccination among the HIV-positive individuals who had lost their anti-HAV antibodies after primary vaccination. Single dose of HAV revaccination may provide rapid and sufficient seroresponses for HAV during the outbreak of acute hepatitis A.

Reduced Seroprevalence of Hepatitis A Virus Among Japanese Healthcare Workers as a Risk Factor for Occupational Infection.

BACKGROUND: With the improvement in sanitation and hygiene, the incidence of hepatitis A virus (HAV) infection has declined, and its seroprevalence among Japanese people has been reduced. Universal HAV vaccination is yet to be implemented in Japan, and the healthcare workers (HCWs) are at higher risks of acquiring this infection. We herein report the seroepidemiology of HAV infection among HCWs at Osaka University Hospital. METHODS: Between September and October 2017, we collected serum samples submitted to our laboratory for HCWs health examination and tested for the anti-HAV antibody. RESULTS: Overall HAV seropositivity rate was 5.1% (22/436 samples). The seroprevalence was higher among those in the twenties (6.0%) and thirties (8.0%), compared to older age groups. CONCLUSIONS: In this age of internationalization, the decreasing immunity for HAV places HCWs at risk of developing the disease. As a preventive measure against occupational infection, HAV vaccination may be needed for Japanese HCWs.