Spillover of a hepatitis A outbreak among men who have sex with men (MSM) to the general population, the Netherlands, 2017

Concurrent Outbreaks of Hepatitis A, Invasive Meningococcal Disease, and Mpox, Florida, USA, 2021-2022

In 2022, concurrent outbreaks of hepatitis A, invasive meningococcal disease (IMD), and mpox were identified in Florida, USA, primarily among men who have sex with men. The hepatitis A outbreak (153 cases) was associated with hepatitis A virus genotype IA. The IMD outbreak (44 cases) was associated with Neisseria meningitidis serogroup C, sequence type 11, clonal complex 11. The mpox outbreak in Florida (2,845 cases) was part of a global epidemic. The hepatitis A and IMD outbreaks were concentrated in Central Florida and peaked during March--June, whereas mpox cases were more heavily concentrated in South Florida and had peak incidence in August. HIV infection was more common (52%) among mpox cases than among hepatitis A (21%) or IMD (34%) cases. Where feasible, vaccination against hepatitis A, meningococcal disease, and mpox should be encouraged among at-risk groups and offered along with program services that target those groups.

High-performance enrichment-based genome sequencing to support the investigation of hepatitis A virus outbreaks

IMPORTANCE

This proof-of-concept study introduces a hybrid capture oligo panel for whole-genome sequencing of all six human pathogenic hepatitis A virus (HAV) subgenotypes, exhibiting a higher sensitivity than some conventional genotyping assays. The ability of hybrid capture to enrich multiple targets allows for a single, streamlined workflow, thus facilitating the potential harmonization of molecular surveillance of HAV with other enteric viruses. Even challenging sample matrices can be accommodated, making them suitable for broad implementation in clinical and public health laboratories. This innovative approach has significant implications for enhancing multijurisdictional outbreak investigations as well as our understanding of the global diversity and transmission dynamics of HAV.

Hepatitis A virus infection

Hepatitis A is a vaccine-preventable infection caused by the hepatitis A virus (HAV). Over 150 million new infections of hepatitis A occur annually. HAV causes an acute inflammatory reaction in the liver that usually resolves spontaneously without chronic sequelae. However, up to 20% of patients experience a prolonged or relapsed course and <1% experience acute liver failure. Host factors, such as immunological status, age, pregnancy and underlying hepatic diseases, can affect the severity of disease. Anti-HAV IgG antibodies produced in response to HAV infection persist for life and protect against re-infection; vaccine-induced antibodies against hepatitis A confer long-term protection. The WHO recommends vaccination for individuals at higher risk of infection and/or severe disease in countries with very low and low hepatitis A virus endemicity, and universal childhood vaccination in intermediate endemicity countries. To date, >25 countries worldwide have implemented such programmes, resulting in a reduction in the incidence of HAV infection. Improving hygiene and sanitation, rapid identification of outbreaks and fast and accurate intervention in outbreak control are essential to reducing HAV transmission.

Durability of serologic responses to inactivated hepatitis A virus vaccination among people living with HIV following acute hepatitis A outbreak: a 5-year follow-up study

Serologic responses to hepatitis A virus (HAV) vaccination may wane among immunocompromised populations. To evaluate the long-term seroresponses to 2-dose HAV vaccination, we retrospectively included people living with HIV (PLWH) who had achieved seroconversion within 12 months after vaccination at a university hospital during an outbreak of acute hepatitis A between 2015 and 2017. PLWH included in the study received either Havrix or Vaqta. The seroresponses were evaluated 60 months after the second dose of vaccination and estimated by the intention-to-treat (ITT) with last-observation-carried-forward (LOCF) and per-protocol (PP) analyses. Overall, 986 PLWH (median age, 34 years and CD4 count, 587 cells/µL) were included. The rates of PLWH with persistent seroprotection at month 60 of vaccination were 90.7% (894/986) and 97.4% (748/768) in the ITT with LOCF and PP analyses, respectively. PLWH with persistent seroprotection had achieved higher peak anti-HAV IgG titers after vaccination and had a slower decline in antibody levels compared with those with seroreversion. In the multivariable analysis, seroreversion at month 60 was associated with body-mass index (per 1-kg/m² increase, AOR, 1.10; 95% CI, 1.04-1.17), lowest-ever CD4 count (per 10-cell/µL increase, AOR 0.98; 95% CI, 0.97-1.00), plasma HIV RNA <200 copies/ml at vaccination (AOR, 0.28; 95% CI, 0.14-0.59), and having received Vaqta as the first dose of HAV vaccination (AOR, 0.44; 95% CI, 0.27-0.70). The seroprotection against HAV remained high in the long-term follow-up among PLWH on antiretroviral therapy after 2-dose HAV vaccination. Regular monitoring of seroresponses and timely administration of HAV vaccines are warranted to maintain seroprotection.

Hepatitis A notifications in the EU/EEA, 2010-2019: what can we learn from case reporting to the European Surveillance System?

BackgroundEuropean Union/European Economic Area (EU/EEA) countries annually report hepatitis A (HepA) notifications to The European Surveillance System (TESSy).AimTo describe EU/EEA HepA notifications from 2010 to 2019 and identify infection drivers and surveillance improvements.MethodsWe analysed demographic, clinical and transmission information of HepA confirmed cases from TESSy. We stratified countries by population susceptibility profile and performed time-series analysis to describe trends in notification rates, sex distribution and travel history.ResultsTwenty-nine EU/EEA countries reported 139,793 HepA cases. Six eastern EU countries reported > 60% of these cases. EU/EEA notification rate during the study period was 3.2 cases per 100,000 population (range 2.7-5.6). Notifications peaked in 2014 and 2017, with marked differences in case demographic characteristics. Notification trends varied across different country susceptibility groups. In 2017, the proportion of males (74%) and case median age (31 years) increased steeply, while no changes occurred in 2014. Travel history showed seasonal case peaks following the summer. More than 47,000 hospitalisations were reported. Annual case fatality was < 0.2% for all years. Information on travel history, hospitalisation, death and mode of transmission was suboptimal.DiscussionApart from some countries in its east, the EU/EEA is characterised by low HepA incidence baseline and susceptible to recurrent large cross-border outbreaks. Analysis of European surveillance data highlighted the need for stronger prevention policies for eastern EU countries, men who have sex with men and travellers. Improving surveillance data-quality will enhance knowledge on food-borne, and travel-related exposures to inform more effective and tailored regional prevention policies.

Hepatitis A Outbreak in Men Who Have Sex with Men Using Pre-Exposure Prophylaxis and People Living with HIV in Croatia, January to October 2022

The hepatitis A virus (HAV) is a highly hepatotropic virus transmitted mainly via the fecal-oral route. The purpose of this study is to describe a prolonged HAV outbreak in HIV-infected men who have sex with men (MSM) and pre-exposure prophylaxis (PrEP) users in Croatia in 2022. Croatia has a centralized system of HIV care and the PrEP service is only available at the University Hospital for Infectious Diseases (UHID), Zagreb. We reviewed all MSM living with HIV and MSM PrEP users at UHID and identified those diagnosed with HAV between January and October 2022. During this period, a total of 1036 MSM living with HIV and 361 PrEP users were followed, and 45 (4.4%) and 32 (8.9%) were diagnosed with HAV, respectively. Most cases were diagnosed in mid-February. A total of 70.1% (726/1036) MSM living with HIV and 82.3% (297/361) PrEP users were susceptible to HAV. Sequencing information was available for 34 persons; in all cases the HAV subtype IA was found. Our findings indicate that both MSM living with HIV and HIV-uninfected PrEP users are vulnerable to HAV infection and might be a potential source for a more widespread HAV epidemic.

Epidemiological Characteristics and Spatio-Temporal Distribution of Hepatitis A in Spain in the Context of the 2016/2017 European Outbreak

The aim of our study was to describe the results of the epidemiological surveillance of hepatitis A infections in Spain in the context of the 2016/2017 European outbreak, particularly of hepatitis A outbreaks reported in the MSM population, incorporating the results of a spatio-temporal analysis of cases. Hepatitis A cases and outbreaks reported in 2016-2017 to the National Epidemiological Surveillance Network were reviewed: outbreaks in which some of the cases belonged to the MSM group were described, and clusters of hepatitis A cases in men and women were analysed using a space-time scan statistic. Twenty-six outbreaks were identified, with a median size of two cases per outbreak, with most of the outbreak-related cases belonging to the 15-44 years-old group. Nearly 85% occurred in a household setting, and in all outbreaks, the mode of transmission was direct person-to-person contact. Regarding space-time analysis, twenty statistically significant clusters were identified in the male population and eight in the female population; clusters in men presented a higher number of observed cases and affected municipalities, as well as a higher percentage of municipalities classified as large urban areas. The elevated number of cases detected in clusters of men indicates that the number of MSM-related outbreaks may be higher than reported, showing that spatio-temporal analysis is a complementary, useful tool which may improve the detection of outbreaks in settings where epidemiological investigation may be more challenging.

Detection and control of an ongoing international outbreak of hepatitis A among the Irish Traveller community beginning September 2020

Hepatitis A virus (HAV) infection is a notifiable disease in Ireland, with national coverage of clinical and laboratory surveillance. In December 2020, a cluster of 11 HAV cases among the Irish Traveller community was detected. The outbreak investigation identified 61 total HAV cases from September 2020 to November 2021. Sequenced isolates were sub-genotype IA with identical genome sequence. Case-patients were predominantly aged under 18 (77%), hospitalised (46%) and lived on communal residential sites. Mass onsite HAV vaccination was employed following failure of initial ring vaccination to contain the outbreak. This is the largest outbreak of HAV described in Ireland, involving spillover to the UK and Netherlands. We recommend mass HAV vaccination and tailored communication for outbreak control in migratory subpopulations.

Hepatitis A Outbreaks and Environmental Circulation of Genotype IA Strains in the São Paulo City, 2017-2018

Hepatitis A virus (HAV) is the major cause of enterically transmitted infectious hepatitis. Between 2016 and 2017, the number of confirmed cases of hepatitis A virus (HAV) increased from 64 to 786 in São Paulo affecting mainly adults aged between 18 and 39 years (80%) and males (88%). To support epidemiological surveillance, the present study monitored the presence of HAV in urban sewage samples collected bimonthly for 1 year (November 2017-November 2018) in the central region of the city, where most of cases were detected. Sewage samples were concentrated by polyethylene glycol precipitation and HAV RNA was quantified by RT-qPCR. Nucleotide sequencing targeting the VP1/2A junction region was carried out to genotype the HAV strains. HAV was detected in 76.9% (40/52) of the samples, with a geometric mean viral load of 5.09 × 10⁴ (± SD 4.51 × 10⁵) genome copies (GC/L) (Mauá Street) and 5.27 × 10⁴ (± SD 1.26 × 10⁶) GC/L (Prestes Maia Avenue). Of the 40 positive samples, 8 were typed as HAV subgenotype IA [100% nucleotide (nt) identity with HAV strain VRD_521_2016]. Highest homology was obtained with sequences from European countries (Italy, Spain) and Israel, all of which had reported recent HAV outbreaks associated with men who have sex with men. Our results highlight that wastewater surveillance is a useful tool to support investigating HAV outbreaks in the community, including circulating genotypes.

Hepatitis A Virus Incidence Rates and Biomarker Dynamics for Plasma Donors, United States

The United States is currently affected by widespread hepatitis A virus (HAV) outbreaks. We investigated HAV incidence rates among source plasma donors in the United States since 2016. Serial donations from HAV-positive frequent donors were analyzed for common biologic markers to obtain a detailed picture of the course of infection. We found a considerable increase in incidence rates with shifting outbreak hotspots over time. Although individual biomarker profiles were highly variable, HAV RNA typically had a high peak and a biphasic decrease and often remained detectable for several months. One donor had a biomarker pattern indicative of previous exposure. Our findings show that current HAV outbreaks have been spilling over into the plasma donor population. The detailed results presented improve our comprehension of HAV infection and related public health aspects. In addition, the capture of full RNA curves enables estimation of HAV doubling time.

A description of a hepatitis A outbreak in men who have sex with men and public health measures implemented in Seine-Maritime department, Normandy, France, 2017

BACKGROUND

In 2016-2017, a European-wide circulation of genotype IA hepatitis A virus was responsible for hepatitis A outbreaks in men who have sex with men (MSM). This study aimed to describe the outbreak investigation in Seine-Maritime department (France) and the control measures implemented accordingly.

METHODS

Outbreak description used data from mandatory reporting and enhanced surveillance of male cases. Confirmed case was genotype IA isolated, possible cases had no reported genotype information. Targeted control measures included communication on sexual practices at risk of hepatitis A transmission and two vaccination campaigns in April 2017 and January 2018. Characteristics of cases and vaccinees were described. We reported the best communication channel for relaying outbreak information and control measures based on the monitoring of social network activities and feedback from vaccinees.

RESULTS

During the outbreak period (December 2016 to December 2017), a total of 48 confirmed outbreak cases and 30 possible outbreak cases were notified. Among them, 69 were male (88%). Two epidemic waves were observed. Cases encountered their partners through gay-dating apps (54%) and in one specific sauna (62%). In response to the outbreak, two vaccination campaigns were deployed. A total of 156 MSM were vaccinated, of whom 56 in a truck parked beside the sauna. Most of the vaccinees had been informed about the campaign through dating apps (44%). Community-based organizations involved in sexual health promotion and other gay social media were very proactive in sharing information about the outbreak and promoting the vaccination campaign through their social media account and also on site (gay venues). Vaccinees reported the same sexual practices at risk of hepatitis A transmission as cases.

CONCLUSIONS

In response to this massive hepatitis A outbreak that affected mostly MSM in Seine-Maritime department, vaccination campaign remained the cornerstone of prevention. Prevention officers from the community-based organization played a key role in vaccination promotion. Gay-dating apps and outdoor sessions of vaccination allowed to effectively reach MSM. Cost-effectiveness studies might analyze the interest of a continuous sexual health promotion including vaccination against hepatitis A in MSM through dating apps and social networks.

Hepatitis A vaccination

Hepatitis A is an important public health issue worldwide. Hepatitis A vaccine (HepA) was first licensed in 1992. Both inactivated HepA (HepA-I) and live attenuated HepA (HepA-L) are highly immunogenic and well tolerated, and immune protection postvaccination can persist for at least 20 y. HepA is effective for both preexposure and postexposure prophylaxis, especially among children and young adults. The strategy of HepA vaccination varies in different countries and mainly includes vaccination among high-risk populations, regional childhood vaccination and universal childhood vaccination. The incidence of hepatitis A has decreased greatly in many countries in the last 30 y, but hepatitis A outbreaks frequently occur among high-risk populations and those who have not been covered by universal child vaccination programs in recent years. Disease surveillance and serosurveys are suggested to clarify the shift in the epidemiology of hepatitis A. The long-term persistence of immune protection after one dose of HepA should be further studied, as well as the cost-effective evaluation of different strategies of HepA vaccination. Based on this evidence, the recommendation on HepA vaccination should be put forward scientifically and updated in a timely and well-implemented manner.

Factors associated with hepatitis A virus infection among HIV-positive patients before and after implementation of a hepatitis A virus vaccination program at a medical centre in central Taiwan

Background Taiwan government has promoted the administration of a hepatitis A vaccine at public expense for high-risk groups as a preventive measure after the outbreak of hepatitis A virus (HAV) infections in 2015. The aim of this study was to evaluate the efficacy of such vaccination policy in patients with human immunodeficiency virus (HIV).

METHODS

From January 2016 to July 2017, we enrolled 658 HIV-positive male participants. Participants were stratified into anti-HAV-positive (n = 165) and anti-HAV-negative (n = 493) groups. A total of 364 anti-HAV-negative patients received vaccination against HAV and were followed up for 1.5 years. A Cox regression model was used to estimate the effects of factors predicting positive anti-HAV detection after vaccination.

RESULTS

Patients with HIV had an anti-HAV-positive prevalence of 25.1% before vaccination. Of the 364 patients inoculated with the first dose of vaccine, 58.0% received the second dose. Seroresponse rates were 50.0% and 80.6%, respectively. Antibody production was 30.0% lower in patients with a CD4 T-cell count <200 cells/µL (adjusted relative risk (ARR) = 0.7; 95% confidence interval (CI) = 0.5-0.9) compared with those with 500 cells/µL. Hepatitis C co-infection reduced the production of antibodies by 50.0% (ARR = 0.5; 95% CI = 0.2-0.8).

CONCLUSION

This study suggests that vaccination against hepatitis A be administered when the immunity of an HIV-positive patient is strong. The promotion of the current vaccination policy against hepatitis A in Taiwan has improved the vaccination rate; the response rate for receiving one dose of the vaccine doubled.

Hepatitis A virus and hepatitis E virus prevalence relates to human immunodeficiency virus infection in Japanese male blood donors

Hepatitis A virus (HAV) has begun to spread globally among men who have sex with men (MSM). Hepatitis E virus (HEV) also may be transmitted through sexual contact among MSM. To assess the current status of these viruses among MSM in Japan, the seroprevalence of both viruses using 503 plasma samples collected between 2009 and 2018 from human immunodeficiency virus (HIV)-positive male donors who were presumed to be mainly MSM was investigated. Our results suggested that HAV may be spreading within this population, as reported elsewhere. By contrast, the spread of HEV was confirmed only among younger HIV-positive donors.

Hepatitis A epidemic in men who have sex with men (MSM) in Milan, Italy

Background and aim of the work:

Hepatitis A is an infectious disease characterized by fecal-oral transmission; however, a rise in sexually-transmitted cases has been observed, particularly among “men who have sex with men”. In Europe, a Hepatitis A epidemic occurred among men who have sex with men between 2016 and 2018. The aim of this study is to describe this Hepatitis A epidemic in the city of Milan and to analyze the incidence of Sexually Transmitted Diseases co-infection among Hepatitis A cases.

Methods:

Hepatitis A cases were traced and identified. Epidemiological data were collected and Hepatitis A vaccination was investigated. Cases were georeferenced, calculating incidence rates for each Milan Municipality. Viral genotypic analysis was carried out.

Results:

353 cases were reported in Milan. Incidence rates resulted significantly higher in males (RR 18.1 CI9 5% 11.5 – 28.4). 70 cases reported foreign travel. 172 cases reported “Men who have Sex with Men” behaviour. Genotypic analysis revealed correlation with strains of the European “Men who have Sex with Men” epidemic. Georeferencing showed asymmetric case distribution. Only 12 cases reported Hepatitis A vaccination. The Relative Risk for syphilis infection among Hepatitis A cases was 133.9 (95% CI 81.7 – 219.7) and 29.7 (95%CI 9.5 – 92.7) for gonorrhea.

Conclusions:

Most genotyped cases (93.7%) correlated to the European Hepatitis A epidemic among Men who have Sex with Men. Georeferencing showed a greater incidence of Hepatitis A cases in areas characterized by the homosexual community. The higher incidence of Sexually Transmitted Diseases co-infection in Hepatitis A cases correlated to clusters responsible for the European Hepatitis A epidemic, suggests increased sexual promiscuity among Men who have Sex with Men. These data support the need for Hepatitis A vaccination programs and sensitization of Men who have Sex with Men to the adoption of safe sexual practices.

Outbreak of hepatitis A genotype IB in Australia associated with imported frozen pomegranate arils

Locally acquired hepatitis A infection is re-emerging in Australia owing to person-to-person outbreaks among men who have sex with men and imported frozen produce. This paper describes a multi-state foodborne outbreak in the first half of 2018. Enhanced human epidemiological investigation including a case-control study, as well as microbial surveillance and trace-back investigations concluded that the outbreak was caused by consumption of imported frozen pomegranate arils. A total of 30 cases of hepatitis A infection, genotype IB with identical sequences met the outbreak case definition, including 27 primary cases and three secondary cases. Twenty-five (83%) of the cases were hospitalised for their illness and there was one death. Imported frozen pomegranate arils from Egypt were strongly implicated as the source of infection through case interviews (19 of 26 primary cases) as well as from a case-control study (adjusted odds ratio 43.4, 95% confidence interval 4.2-448.8, P = 0.002). Hepatitis A virus (HAV) was subsequently detected by polymerase chain reaction in two food samples of the frozen pomegranate aril product. This outbreak was detected and responded to promptly owing to routine genetic characterisation of HAVs from all hepatitis A infections in Australia as part of a national hepatitis A enhanced surveillance project. This is now the third outbreak of hepatitis A in Australia from imported frozen fruits. A re-assessment of the risk of these types of imported foods is strongly recommended.

Community outbreak of hepatitis A disproportionately affecting men who have sex with men in Toronto, Canada, January 2017-November 2018

Background

In late 2016 and early 2017, a number of countries began reporting hepatitis A virus (HAV) outbreaks involving person-to-person transmission among men who have sex with men (MSM), people using illicit drugs and homeless or underhoused persons.

Objective

To describe the epidemiology and public health response to an outbreak of HAV disproportionately affecting MSM in Toronto, Canada from January 2017 to November 2018.

Methods

Following an increase in the number of cases of HAV in MSM being reported in other countries, enhanced surveillance was performed for all non-travel-related cases of HAV reported from June 1, 2017 to November 1, 2018, including a retrospective analysis of cases reported from January 2017 to June 2017. Descriptive analysis and viral sequencing were performed to describe person-to-person transmission patterns and target interventions. Control strategies included interventions to promote the uptake of preexposure HAV vaccination, including social media campaigns geared to MSM, messaging to healthcare providers and vaccine clinics.

Results

Based on the outbreak case definitions, 52 confirmed and probable cases of HAV were identified. Over 80% of outbreak cases were male (n=43/52) and, among those for whom data were available, 64% (n=25/39) reported an MSM exposure. Data on hospitalization was available for 51 cases; 56% of confirmed cases (n=23/41) and 40% of probable cases (n=4/10) required hospitalization. Of the cases with serum samples that had HAV sequencing, 83% (n=30/36) had one of the three strains seen circulating in outbreaks among MSM internationally; 72% (n=26/36) were VRD_521_2016, which had been detected in recently reported European outbreaks among MSM. Targeted promotion of publicly-funded vaccination using social media platforms popular with MSM and targeted vaccine clinics were developed to promote HAV awareness and vaccine uptake among MSM.

Conclusion

Outbreaks of HAV, attributed to person-to-person transmission of strains of HAV that disproportionately affected MSM and were likely to have been imported from international MSM outbreaks, have now occurred in Canada. Genetic sequencing of HAV, risk factor analysis of cases, monitoring trends of vaccine coverage in high-risk groups and initiation of vaccination campaigns that address barriers to HAV preexposure vaccine coverage in the MSM population may prevent future outbreaks.

Antiretroviral Medications for the Prevention of HIV Infection: A Clinical Approach to Preexposure Prophylaxis, Postexposure Prophylaxis, and Treatment as Prevention

Preventing new human immunodeficiency virus (HIV) infections is essential to halting the global pandemic. HIV prevention strategies include integrating both nonpharmacologic (eg, safe sexual counseling, circumcision) and pharmacologic approaches. Several pharmacologic HIV prevention strategies are increasingly used globally and include postexposure prophylaxis, preexposure prophylaxis, and treatment as prevention. These prevention modalities have enormous clinical and public health appeal, as they effectively reduce HIV acquisition in individuals and also may lower HIV incidence in communities when integrated and implemented broadly. Efforts are now underway to scale HIV prevention programs using these techniques in both high- and low-resource settings.

Hepatitis A Outbreak in the General Population due to a MSM-Associated HAV Genotype Linked to a Food Handler, November 2017-February 2018, Germany

Hepatitis A (HAV) is a viral infection causing a range of symptoms, sudden onset of fever, malaise, diarrhea, and jaundice. It is mostly transmitted fecal-oral through contaminated food, with immediate household and sexual contacts having a higher risk of infection. Since 2016 an increased number of HAV infections, mostly affecting men who have sex with men (MSM) have been noticed worldwide, with three main genotypes circulating. We report here on the first spillover outbreak of the MSM-associated HAV genotype RIVM-HAV16-090 in the German general population in November 2017-February 2018. In total, twelve cases could be attributed to the outbreak with the index case and a coworker in a butchers shop being the most probable source of the outbreak. The identical HAV genotype was detected in two environmental samples in the premises of the butchers shop and in nine cases. Outbreak control measures included detailed contact tracing and stool examinations, several environmental investigations, thorough cleaning, and disinfection of the premises of the butchers shop. Post-exposure vaccination was recommended to all unprotected contacts during the investigation. Furthermore, although hand-washing facilities were in accordance with the required law, additional installment of soap and disinfectant dispensers and contactless faucets has been recommended.

Hepatitis A incidence, seroprevalence, and vaccination decision among MSM in Amsterdam, the Netherlands

BACKGROUND

Several outbreaks of Hepatitis A virus (HAV) were recently documented among men who have sex with men (MSM) in Europe. We investigated the HAV incidence among MSM in Amsterdam, the Netherlands; and HAV seroprevalence and HAV vaccination decision among MSM visiting the Sexually Transmitted Infection (STI) clinic in Amsterdam.

METHODS

Using surveillance data from 1992 to 2017 of MSM with acute HAV in Amsterdam, we estimated the incidence by calendar year and age. We explored HAV seroprevalence by calendar year and age, determinants for HAV seropositivity, and opting-in/out for HAV vaccination using data collected among MSM that visited the STI clinic between 2006 and 2017 and were included in a nationwide Hepatitis B virus (HBV) vaccination programme. Offering HAV vaccination at the STI clinic differed over three consecutive periods: not offered, offered for free, or offered for 75 euros. Logistic regression analyses were used to explore determinants.

RESULTS

HAV incidence increased in 2016/17 after 4 years of absence and peaked in MSM around 35 years of age. Among MSM visiting the STI clinic, HAV seroprevalence was 37% (95%CI = 35-40%), which was constant over the period 2006-2017, and increased with age (p < 0.001). Determinants for HAV seropositivity in multivariable analysis were: older age (p < 0.001), originating from an HAV endemic country (p < 0.001), and being HBV seropositive (p = 0.001). MSM opted-in more frequently when HAV vaccination was offered for free versus paid (89% versus 11%, respectively; p < 0.001). Younger MSM were less inclined to vaccinate when payment was required (p = 0.010). Post-hoc analyses showed that 98% versus 46% of MSM visiting the Amsterdam STI clinic would be protected against HAV infection if HAV vaccination was offered for free or for 75 euros, respectively.

CONCLUSIONS

The MSM population of Amsterdam is vulnerable to a new HAV outbreak. We strongly recommend that MSM have access to free hepatitis A vaccination.