Epidemiology and prevention of hepatitis A in travelers

Global burden and trends of acute viral hepatitis among children and adolescents from 1990 to 2019: a systematic analysis of the Global Burden of Disease Study 2019

BACKGROUND

Children and adolescents are at high risk for acute viral hepatitis (AVH), but epidemiological research focusing on them has been overshadowed by adult chronic B and C. We provide global, regional, and national estimates of the AVH burden and their trends on people under 20 years from 1990 to 2019.

METHODS

AVH data from Global Burden of Disease Study (GBD) 2019 was used. Incidence and disability-adjusted life years (DALYs) were calculated, analyzing trends with estimated annual percentage change (EAPC) and Joinpoint regression.

RESULTS

In 2019, 156.39 (95% uncertainty interval 145.20-167.16) million new cases of AVH were reported among children and adolescents globally, resulting in 1.98 (1.50-2.55) million DALYs. Incidence rates for young children (< 5 years), older children (5-9 years), and adolescents (10-19 years) were 12,799 (11,068-14,513), 5,108 (4829-5411), and 3020 (2724-3339) per 100,000 population, respectively. The global AVH incidence displayed a linear decline with an EAPC of - 0.66 (- 0.68 to - 0.65). High-incidence regions included sub-Saharan Africa, Oceania, South Asia, and Central Asia, with India, Pakistan, and Nigeria facing the greatest burden. Leading causes were hepatitis A, followed by hepatitis E, B, and C. All hepatitis types showed declining trends, especially hepatitis B. Furthermore, we confirmed the association between the AVH incidence and the socioeconomics, vaccine, and advanced liver diseases.

CONCLUSION

Effective vaccines and treatments for hepatitis B and C offer eradication opportunities. Broadening diagnostic and therapeutic coverage is vital to address disparities in service provision for children and adolescents.

Nonspecific Effects of Infant Vaccines Make Children More Resistant to SARS-CoV-2 Infection

A myriad of reasons, or a combination of them, have been alluded to in order to explain the lower susceptibility of children to SARS-CoV-2 infection and the development of severe forms of COVID-19. This document explores an additional factor, still little addressed in the medical literature related to the matter: nonspecific resistance to SARS-CoV-2 that could be generated by vaccines administered during childhood. The analysis carried out allows one to conclude that a group of vaccines administered during childhood is associated with a lower incidence and severity of SARS-CoV-2 infection among pediatric ages. Looking from an epidemiological perspective, this conclusion must be taken into consideration in order to ensure greater rationality in the design and implementation of prevention and control actions, including the administration of the COVID-19 vaccine, for these ages.

Acute hepatitis A in international travellers: a GeoSentinel analysis, 2008-2020

BACKGROUND

Non-immune international travellers are at risk of acquiring hepatitis A. Although hepatitis A vaccination is recommended for unvaccinated travellers to high or intermediate hepatitis A virus endemicity, compliance with this recommendation is not universal.The main objective was to describe the demographic and travel characteristics of international travellers infected with hepatitis A during travel.

METHODS

Available data on travellers with confirmed (positive molecular test) or probable (symptomatic individuals with a single positive IgM test) hepatitis A diagnosed during and after travel from January 2008 to December 2020 were obtained from the GeoSentinel Surveillance Network database. We analysed demographic and travel characteristics of infected travellers.

RESULTS

Among 254 travellers with hepatitis A (185 confirmed and 69 probable), the median age was 28 years (interquartile range: 19-40), 150 (59%) were male, and among 54 travellers with information available, 53 (98%) were unvaccinated. The most common reasons for travel included tourism (n = 120; 47%) and visiting friends or relatives (VFR; n = 72; 28%). About two-thirds of VFR travellers with hepatitis A (n = 50; 69%) were younger than 20 years old. Hepatitis A was acquired most frequently in South-Central Asia (n = 63; 25%) and sub-Saharan Africa (n = 61; 24%), but 16 travellers (6%) acquired hepatitis A in regions with low endemicity including Western Europe (n = 7; 3%), the Caribbean (n = 6; 2%) and North America (n = 3; 1%). Median duration from illness onset to GeoSentinel site presentation was ~7 days (interquartile range : 4-14 days). Among 88 travellers with information available, 59% were hospitalized.

CONCLUSIONS

Despite availability of highly effective vaccines, travellers still acquire hepatitis A, even when traveling to low-endemicity destinations. Providing pre-departure hepatitis A vaccine to susceptible travellers is crucial to reducing travel-associated hepatitis A and should be offered to all travellers as part of the pre-travel consultation, regardless of destination.

Clinical experience with the inactivated hepatitis A vaccine, Avaxim 80U Pediatric

INTRODUCTION

Hepatitis A, caused by hepatitis A virus (HAV), is primarily transmitted via the fecal/oral route either through ingestion of contaminated food and water or through direct contact with an infectious person. Prevalence of hepatitis A is strongly correlated with socioeconomic factors, decreasing with increased socio-economic development, access to clean water and sanitation. Vaccination against HAV should be part of a comprehensive plan for the prevention and control of viral hepatitis, either as part of regular childhood immunization programs or with other recommended vaccines for travelers. Areas covered: We present here evidence for the immunogenicity and safety of an inactivated HAV pediatric vaccine (Avaxim® 80U Pediatric, Sanofi Pasteur), indicated for use in children aged 12 months to 15 years. Data evaluated are from trials undertaken during the clinical development of this vaccine, a systematic literature review and post-market pharmacovigilance. Expert opinion: The pediatric HAV vaccine is highly immunogenic and generates long-lasting protection against hepatitis A disease in children. The safety and immunogenicity data presented in this review suggest that the pediatric HAV vaccine is a valuable option in the prevention of HAV infection in children in many areas of the world where the disease remains a healthcare issue.

Hepatitis A virus infections, immunisations and demographic determinants in children and adolescents, Germany

Hepatitis A is a vaccine-preventable disease with a global distribution. It predominantly occurs in regions with inadequate living conditions, but also affects populations in industrialised countries. Children are frequently involved in the transmission of hepatitis A virus (HAV) and thus play a central role in the epidemiology of hepatitis A. Here, we investigated HAV infections, immunisations, and associated demographic determinants in a nationwide, population-based, cross-sectional survey conducted in Germany from 2003-2006. Out of 17,640 children and adolescents, complete data sets (HAV serology, demographic information and vaccination card) were available for 12,249 (69%), all aged 3-17 years. We found protective antibody levels (>=20 IU/L) in 1,755 (14%) individuals, 1,395 (11%) were vaccinated against hepatitis A, 360 (3%) individuals were HAV seropositive without prior hepatitis A vaccination, thus indicating a previous HAV infection. Antibody prevalence (attributable to vaccination or infection) increased significantly with age. Multivariate logistic regression revealed that predominantly children and adolescents with migration background-even if they were born in Germany-are affected by HAV infections. Our results provide a rationale to emphasise existing vaccination recommendations and, moreover, to consider additional groups with a higher risk of infection for targeted vaccination, especially children with a migration background.

Tour leaders with detailed knowledge of travel-related diseases play a key role in disease prevention

In Taiwan, group tours are a popular mode of international travel; hence, group tour leaders must ensure traveler safety and health. This study identified factors influencing tour leaders' willingness to recommend pretravel medical consultation and vaccination.A cross-sectional questionnaire survey was administered to tour leaders from January 2011 to December 2012. Multivariate logistic regression analyses were performed to estimate the odds ratios of having a positive attitude and willingness based on different knowledge scores of the tour leaders after adjustments for age, sex, education level, and seniority.Tour leaders with a more detailed knowledge of both travel-related infectious and noninfectious diseases demonstrated a higher willingness to receive vaccination. They believed that consultation at travel clinics before travel can improve travelers' health (P < .05).This study supports the importance and effectiveness on educating tour leaders' knowledge about travel-related diseases to improve health care for travelers.

Evolution of hepatitis A virus seroprevalence among HIV-positive adults in Taiwan

OBJECTIVES

The study aimed to describe the seroprevalence of hepatitis A virus (HAV) in HIV-positive adult patients in Taiwan between 2012 and 2016 and to examine the evolution of HAV seroprevalence between 2004-2007 and 2012-2016.

METHODS

Clinical information and data of anti-HAV antibody results were collected from 2,860 antiretroviral-naïve HIV-positive Taiwanese aged 18 years or older who initiated combination antiretroviral therapy at 11 hospitals around Taiwan between 2012 and 2016 (2012-2016 cohort). A multivariate logistic regression model was applied to identify independent variables associated with HAV seropositivity. Comparisons of HAV seroprevalences and associated clinical characteristics were made between this 2012-2016 cohort and a previous cohort of 1580 HIV-positive patients in 2004-2007 (2004-2007 cohort).

RESULTS

Of the 2,860 HIV-positive patients between 2012 and 2016, the overall HAV seropositivity rate was 21.2% (605/2860), which was independently associated with an older age (adjusted odds ratio [AOR], per 1-year increase, 1.13; 95% confidence interval [95% CI], 1.11-1.15) and co-infection with hepatitis B virus (AOR 1.44; 95% CI, 1.08-1.93). Residence in southern Taiwan (AOR 0.49; 95% CI, 0.34-0.72) was inversely associated with HAV seropositivity. The overall HAV seroprevalence in the 2012-2016 cohort was significantly lower than that in the 2004-2007 cohort (21.2% vs 60.9%, p<0.01). The decreases of HAV seropositivity rate were observed in nearly every age-matched group, which suggested the cohort effect on HAV seroepidemiology. However, among individuals aged 25 years or younger, the HAV seropositivity rate increased from 3.8% (2/52) in the 2004-2007 cohort to 8.5% (50/587) in the 2012-2016 cohort, with 95.4% (560/587) being MSM in this age group of the latter cohort.

CONCLUSIONS

HAV seroprevalence has decreased with time among HIV-positive adults in Taiwan. The cohort effect has increased the number of young HIV-positive patients that are susceptible to HAV infection in a country without nationwide childhood vaccination program against HAV.

Guidelines for the prevention of travel-associated illness in older adults

International travel to the developing world is becoming more common in elderly patients (defined here as individuals greater than 65 years old). When providing pre-travel counseling, providers must appreciate the changing physiology, comorbidities, immunity and pharmacokinetics associated with the aging process to prepare elderly patients for the stressors of international travel. These guidelines present an evidence-based approach to pre-travel counseling, immunization, and pharmacology concerns unique to elderly patients seeking care in a travel clinic setting.

Hepatitis A outbreak among men who have sex with men (MSM) predominantly linked with the EuroPride, the Netherlands, July 2016 to February 2017

Between July 2016 and February 2017, 48 male cases of hepatitis A were notified in the Netherlands. Of these, 17 identified as men who have sex with men (MSM). Ten of the 13 cases for whom sequencing information was available, were infected with a strain linked with the EuroPride that took place in Amsterdam in 2016. This strain is identical to a strain that has been causing a large outbreak among MSM in Taiwan.

Age-period-cohort analysis of hepatitis A incidence rates in Korea from 2002 to 2012

OBJECTIVES

This study aimed to evaluate the epidemiology of hepatitis A in Korea from 2002 to 2012 using age-period-cohort analyses.

METHODS

We used claims data from the Korean National Health Insurance Corporation for the entire population. Census data from 2010 were used as the standard population. The incidence of hepatitis A was assumed to have a Poisson distribution, and the models and effects were evaluated using the intrinsic estimator method, the likelihood ratio, and the Akaike information criterion.

RESULTS

The incidence of hepatitis A gradually increased until 2007 (from 17.55 to 35.72 per 100,000 population) and peaked in 2009 (177.47 per 100,000 population). The highest incidence was observed among 27-29-year-old individuals when we omitted data from 2005 to 2007. From 2005 to 2007, the peak incidence was observed among 24-26-year-old individuals, followed by 27-29-year-olds. The best model fits were observed when the age-period-cohort variables were all considered at the same time for males, females, and the whole population.

CONCLUSIONS

The incidence of hepatitis A exhibited significant age-period-cohort effects; its incidence peaked in 2009 and was especially high among Koreans 20-39 years of age. These epidemiological patterns may help predict when high incidence rates of hepatitis A may occur in developing countries during their socioeconomic development.

Pre-travel advice, attitudes and hepatitis A and B vaccination rates among travellers from seven countries†

BACKGROUND

Knowledge about the travel-associated risks of hepatitis A and B, and the extent of pre-travel health-advice being sought may vary between countries.

METHODS

An online survey was undertaken to assess the awareness, advice-seeking behaviour, rates of vaccination against hepatitis A and B and adherence rates in Australia, Finland, Germany, Norway, Sweden, the UK and Canada between August and October 2014. Individuals aged 18-65 years were screened for eligibility based on: travel to hepatitis A and B endemic countries within the past 3 years, awareness of hepatitis A, and/or combined hepatitis A&B vaccines; awareness of their self-reported vaccination status and if vaccinated, vaccination within the last 3 years. Awareness and receipt of the vaccines, sources of advice, reasons for non-vaccination, adherence to recommended doses and the value of immunization reminders were analysed.

RESULTS

Of 27 386 screened travellers, 19 817 (72%) were aware of monovalent hepatitis A or combined A&B vaccines. Of these 13 857 (70%) had sought advice from a healthcare provider (HCP) regarding combined hepatitis A&B or monovalent hepatitis A vaccination, and 9328 (67%) were vaccinated. Of 5225 individuals eligible for the main survey (recently vaccinated = 3576; unvaccinated = 1649), 27% (841/3111) and 37% (174/465) of vaccinated travellers had adhered to the 3-dose combined hepatitis A&B or 2-dose monovalent hepatitis A vaccination schedules, respectively. Of travellers partially vaccinated against combined hepatitis A&B or hepatitis A, 84% and 61%, respectively, believed that they had received the recommended number of doses.

CONCLUSIONS

HCPs remain the main source of pre-travel health advice. The majority of travellers who received monovalent hepatitis A or combined hepatitis A&B vaccines did not complete the recommended course. These findings highlight the need for further training of HCPs and the provision of reminder services to improve traveller awareness and adherence to vaccination schedules.

Refusal of recommended travel-related vaccines among U.S. international travellers in Global TravEpiNet

BACKGROUND

International travellers are at risk of travel-related, vaccine-preventable diseases. More data are needed on the proportion of travellers who refuse vaccines during a pre-travel health consultation and their reasons for refusing vaccines.

METHODS

We analyzed data on travellers seen for a pre-travel health consultation from July 2012 through June 2014 in the Global TravEpiNet (GTEN) consortium. Providers were required to indicate one of three reasons for a traveller refusing a recommended vaccine: (1) cost concerns, (2) safety concerns or (3) not concerned with the illness. We calculated refusal rates among travellers eligible for each vaccine based on CDC recommendations current at the time of travel. We used multivariable logistic regression models to examine the effect of individual variables on the likelihood of accepting all recommended vaccines.

RESULTS

Of 24 478 travellers, 23 768 (97%) were eligible for at least one vaccine. Travellers were most frequently eligible for typhoid (N = 20 092), hepatitis A (N = 12 990) and influenza vaccines (N = 10 539). Of 23 768 eligible travellers, 6573 (25%) refused one or more recommended vaccine(s). Of those eligible, more than one-third refused the following vaccines: meningococcal: 2232 (44%) of 5029; rabies: 1155 (44%) of 2650; Japanese encephalitis: 761 (41%) of 1846; and influenza: 3527 (33%) of 10 539. The most common reason for declining vaccines was that the traveller was not concerned about the illness. In multivariable analysis, travellers visiting friends and relatives (VFR) in low or medium human development countries were less likely to accept all recommended vaccines, compared with non-VFR travellers (OR = 0.74 (0.59-0.95)).

CONCLUSIONS

Travellers who sought pre-travel health care refused recommended vaccines at varying rates. A lack of concern about the associated illness was the most commonly cited reason for all refused vaccines. Our data suggest more effective education about disease risk is needed for international travellers, even those who seek pre-travel advice.

A retrospective pooled analysis assessing the effect of age on the immunogenicity of Havrix™ in healthy adults

Over recent decades, the global incidence of hepatitis A virus infection has been reduced by improvements in sanitation infrastructure and through immunization programs. The immunogenicity and field efficacy of the inactivated hepatitis A vaccine (Havrix™, GSK, Belgium) has been demonstrated in clinical trials, population-impact studies as well as in several outbreak settings. However, immunological data in older populations are limited, with only few studies assessing the immune response of this vaccine in adults aged ≥40 years. This retrospective pooled analysis of 4 2-dose primary vaccination studies compared the immunogenicity and safety of the inactivated hepatitis A vaccine in adults aged ≥40 years with subjects aged 20–30 years (control group; N = 80 in each group). Fifteen days after the first vaccine dose, 79.7% (95% CI: 68.8–88.2) and 92.3% (95% CI: 84.0–97.1) of subjects were seropositive in the ≥40 years and control groups, respectively; 97.5% (95% CI: 91.2–99.7) and 97.4% (95% CI: 91.0–99.7), respectively, were seropositive one month after the first dose. All subjects in both groups (95% CIs: 95.4–100 and 95.3–100, respectively) were seropositive one month after the second dose. Safety profiles were similar in both groups. In conclusion, the inactivated hepatitis A vaccine induced similar immune responses in adults aged ≥40 and 20–30 years one month after the first and second dose whereas younger subjects may demonstrate a higher seroconversion rate 15 days after the first dose.

HAV & HBV vaccination among travellers participating in the National Health and Wellness Survey in five European countries

BACKGROUND

A main cause of hepatitis A and B infections in European countries is travel to endemic countries. Most research on hepatitis vaccination among travellers from Europe has been conducted in airports or travel clinics, samples which potentially overrepresented frequent travellers.

METHODS

2102 respondents across France, Germany, Italy, Spain, and UK completed an internet-based questionnaire. Vaccination status, travel to endemic countries, and other characteristics were compared across frequent, occasional, and non-travellers. Logistic regressions tested association between vaccination and travel adjusting for potential confounders.

RESULTS

Most respondents were occasional travellers (61%) and 24% were frequent travellers. Frequent travellers had 2.3-2.4 times the odds of being vaccinated relative to non-travellers, and odds of vaccination were 2.5-3.1 times higher among travellers to endemic areas relative to others (all p < .05). Frequent travellers were more aware of their vaccination status (HAV: 80% vs. 72%; HBV: 82% vs. 74%), though many who were vaccinated could not identify the number of injections to complete the series (47% vs. 29%) (all p < .05).

CONCLUSION

Travel frequency and destination endemicity are associated with increased hepatitis A and B vaccination. The number of unvaccinated travellers and the lack of recall for the dosing schedule suggest the need to improve travellers' awareness and adherence to recommendations.

Patient awareness of need for hepatitis a vaccination (prophylaxis) before international travel

INTRODUCTION

Although hepatitis A virus (HAV) infection is preventable through vaccination, cases associated with international travel continue to occur. The purpose of this study was to examine the frequency of international travel and countries visited among persons infected with HAV and assess reasons why travelers had not received hepatitis A vaccine before traveling.

METHODS

Using data from sentinel surveillance for HAV infection in seven US counties during 1996 to 2006, we examined the role of international travel in hepatitis A incidence and the reasons for patients not being vaccinated.

RESULTS

Of 2,002 hepatitis A patients for whom travel history was available, 300 (15%) reported traveling outside of the United States. Compared to non-travelers, travelers were more likely to be female [odds ratio (OR) = 1.74 (95% confidence interval [95% CI], 1.35, 2.24)], aged 0 to 17 years [OR = 3.30 (1.83, 5.94)], Hispanic [OR = 3.69 (2.81, 4.86)], Asian [OR = 2.00 (1.06, 3.77)], and were less likely to be black non-Hispanic [OR = 0.30 (0.11, 0.82)]. The majority, 189 (61.6%), had traveled to Mexico. The most common reason for not getting pre-travel vaccination was "Didn't know I could [or should] get shots" [100/154 (65%)].

CONCLUSION

Low awareness of HAV vaccination was the predominant reason for not being protected before travel. Different modes of traveler education could improve prevention of hepatitis A. To highlight the risk of infection before traveling to endemic countries including Mexico, travel and consulate websites could list reminders of vaccine recommendations.

Immunogenicity and safety of concomitant administration of a combined hepatitis A/B vaccine and a quadrivalent meningococcal conjugate vaccine in healthy adults

BACKGROUND

This phase 3b randomized, open-label study evaluated the immunogenicity and safety of coadministration of a hepatitis A and/or B vaccine with a quadrivalent oligosaccharide meningococcal CRM197 -conjugate vaccine (MenACWY-CRM), in the context of an accelerated hepatitis A and/or B immunization schedule.

METHODS

A total of 252 healthy adult subjects were randomized to three groups to receive hepatitis A/B only (HepA/B), hepatitis A/B coadministered with MenACWY-CRM (HepA/B+MenACWY-CRM), or MenACWY-CRM only (MenACWY-CRM). Hepatitis A and/or B vaccination was administered in the form of a single booster dose or a primary three-dose series, depending on the hepatitis A and/or B vaccination history of subjects. Antibody responses to hepatitis A/B vaccination were assessed 1 month following the last hepatitis A and/or B dose. Serum bactericidal activity with human complement (hSBA) against meningococcal serogroups A, C, W-135, and Y was assessed 1 month post-MenACWY-CRM vaccination. Safety was monitored throughout the study.

RESULTS

At 1 month following the final hepatitis A and/or B vaccination, concomitant administration of hepatitis A/B and MenACWY-CRM was non-inferior to administration of hepatitis A/B alone in terms of geometric mean concentrations of antibodies against the hepatitis A and B antigens. One month post-MenACWY-CRM vaccination, the percentages of subjects achieving hSBA titers ≥8 for serogroups A, C, W-135, and Y in the HepA/B+MenACWY-CRM group (76, 87, 99, and 94%, respectively) were comparable to those in the MenACWY-CRM group (67, 82, 96, and 88%, respectively). The percentages of subjects reporting adverse events (AEs) were similar across study groups and a majority of the reported AEs were mild to moderate in nature. There were no study vaccine-related serious AEs.

CONCLUSIONS

MenACWY-CRM can be administered concomitantly with a hepatitis A and/or B vaccine in the context of an accelerated hepatitis A and/or B immunization schedule without increasing safety concerns or compromising the immune responses to any of the vaccine antigens. [NCT01453348].