Hepatitis A disease following the implementation of universal vaccination: who is at risk?

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.

The impact of a national routine immunisation programme initiated in 1999 on Hepatitis A incidence in Israel, 1993 to 2012

Data on long-term impact of universal national vaccination programmes against hepatitis A are lacking. We aimed at evaluating the impact on hepatitis A incidence of the Israeli toddlers-only universal routine two-dose vaccination programme against hepatitis A initiated in 1999. All hepatitis A episodes reported to the national surveillance system from 1993 to 2012 were analysed in relation to the vaccination programme and coverage. Mean vaccine coverage in Israel between 2003 and 2010 was 92% for the first dose, given at 18 months of age, and 88% for the second dose, given at 24 months. The annual hepatitis A incidence declined from a mean of 50.4 per 100,000 in the period between 1993 and 1998 to a mean of?<1.0, during the period from 2008 to 2012, representing a reduction of?>98%. The decline was evident in all ages and ethnicity groups, including unvaccinated populations. Of the 1,247 cases reported nationwide between 2002 and 2012, the vaccination status could be ascertained in 1,108 (89%). Among them, only 20 (2%) were reported be vaccinated with one dose and three (<1%) received two doses. The sustained results of this long-term impact study suggest that a toddlers-only universal routine two-dose vaccination programme is highly effective and practical. These findings underscore the importance of sustainability in both the surveillance systems and vaccination programmes and will aid to determine vaccination policies.

Live attenuated hepatitis A vaccines developed in China

Two live, attenuated hepatitis A vaccines, H 2 and LA-1 virus strains, were developed through serial passages of the viruses in cell cultures at 32 °C and 35 °C respectively. Both vaccines were safe and immunogenic, providing protection against clinical hepatitis A in 95% of the vaccinees, with a single dose by subcutaneous injection. The vaccine recipients were not protected from asymptomatic, subclinical hepatitis A virus (HAV) infection, which induced a similar antibody response as for unvaccinated subjects. A second dose caused anamnestic response and can be used for boosting. Oral immunization of human with H 2 vaccine or of marmoset with LA-1 vaccine failed, and no evidence was found for person-to-person transmission of the H 2 strain or for marmoset-to-marmoset transmission of LA-1 strain, by close contact. H 2 strain was genetically stable when passaged in marmosets, humans or cell cultures at 37 °C; 3 consecutive passages of the virus in marmosets did not cause virulence mutation. The live vaccines offer the benefits of low cost, single dose injection, long- term protection, and increased duration of immunity through subclinical infection. Improved sanitation and administration of 150 million doses of the live vaccines to children had led to a 90% reduction in the annual national incidence rate of hepatitis A in China during the 16-year period, from 1991 to 2006. Hepatitis A immunization with both live and inactivated HA vaccines was implemented in the national routine childhood immunization program in 2008 and around 92% of the 16 million annual births received the affordable live, attenuated vaccines at 18 months of age. Near elimination of the disease was achieved in China for 14 years following introduction of the H 2 live vaccine into the Expanded Immunization Program (EPI) in 1992.

Dynamics of childhood invasive meningococcal disease in Israel during a 22-year period (1989-2010)

AIM

To describe the dynamics in the incidence of childhood invasive meningococcal disease (IMD) in Israel during a 22-year period (1989-2010).

METHODS

A longitudinal prospective surveillance in all 27 medical centers with pediatric services in Israel. All cases of children <15 years old with positive blood/cerebrospinal fluid (CSF) culture for Neisseria meningitidis were reported. Demographic, clinical, and bacteriological data were recorded. Meningococcal vaccine was not routinely given to Israeli children during the study period.

RESULTS

The mean age ± standard deviation (SD) among the 743 cases was 40.7 ± 40.2 months. The mean yearly incidence/100,000 was 2.0 ± 0.8. Age-specific incidences were 8.7 ± 2.8, 2.9 ± 1.5, and 0.8 ± 0.5 for children <1, 1-4, and >4 years old, respectively. The overall incidence decreased significantly from 3.7 in 1989 to 1.5 in 2010. Meningitis constituted 69.2 % of all cases. The most common serogroups were: B (76.9 %), C (10.9 %), Y (8.0 %), and W(135) (2.9 %). 78.6 % of all serogroup B isolates were from children <5 years old (p < 0.01). Serogroup C was found mainly in children ≥5 years old (63.4 %). The case fatality rates (CFRs) for children <1, 1-4, >4 years old, and the total study population were 9.2, 12.3, 7.7, and 9.9 %, respectively. CFRs were higher for children without meningitis (14.9 %) compared to children with meningitis (7.9 %) (p < 0.01).

CONCLUSIONS

Overall, and for serogroups B and W135, childhood IMD rates decreased significantly in Israel during the study period, without routine vaccine usage. The most common serogroup in all age groups was B, which was most prevalent in children <5 years old. No change in the trend of the overall CFR was noted during the study period.

Rapid reduction in invasive pneumococcal disease after introduction of PCV7 into the National Immunization Plan in Israel

BACKGROUND

The 7-valent conjugated vaccine (PCV7) was introduced into the Israeli National Immunization Program (NIP) in July 2009 (2, 4, 12 months schedule; 2 dose catch-up in second year of life). Nationwide active prospective surveillance on invasive pneumococcal disease (IPD) has been conducted in children since 1989. In the current study, IPD epidemiology in children <5 years during the 20 years before and 18 months after PCV7 NIP initiation, is reported.

METHODS

All 27 centers performing blood/cerebrospinal fluid (CSF) cultures in children reported monthly IPD cases. Capture-recapture approach was used for completeness.

RESULTS

During 1989-2010, 6022 IPD cases were reported in children <5 years; PCV7 serotypes (7VST) caused ∼50% of all episodes. In 2009 and 2010, 7VST IPD incidences <5 years of age (per 100,000) were 15.9 and 5.4, respectively (a 43% and 81% decrease, respectively) compared to 2003-2007 (mean incidence 27.8). Serotype 6A dynamics resembled those of 7VST. The respective overall IPD incidence decreases were 23% and 42%. The incidence dynamics of serotypes 1, 3, 5, 7F and 19A IPD were characterized by considerable fluctuations over the study period without any upwards or downwards trend in any of the age groups. The overall incidence of serotypes not included in the 13-valent pneumococcal conjugate vaccine (PCV13) did not vary significantly during the study period. By the end of 2010, 72% of the remaining IPD was caused by pneumococcal serotypes included in PCV13.

CONCLUSIONS

An active prospective long-term surveillance, showed a rapid and sharp decline in IPD in children <5 years following initiation of NIP with PCV7. No serotype replacement has been observed so far. The transition from PCV7 to PCV13 initiated in October 2010 may lead to a further substantial decrease in IPD. Follow-up is needed to better determine the long-term PCV effects.

A case of hepatitis a vaccination failure in an HIV-positive man who had sex with men in Israel

Hepatitis A virus (HAV) vaccination is recommended for men who have sex with men (MSM) and other susceptible populations, who are at increased risk for HAV infection, such as HIV-positive persons. Vaccines failures are uncommon, and in HIV-positive individuals whose CD4 count is ≥500 cells/mm2, seroconversion is achieved in 73–94% of vaccinees following the second dose. Data were retrieved from the patient's file at the sexually transmitted disease clinic and the AIDS clinic describing this rare case of vaccine failure. A 35-year-old, HIV-positive MSM was vaccinated against HAV on 2007, while his CD4 count was 551 cells/mm2. Two years later, he was hospitalized due to acute HAV. The patient's serum drawn two months prior to the onset of acute HAV was retrospectively tested and showed no response to the vaccine. The source of the HAV infection was not identified. The patient's partner who was HIV-negative and had been vaccinated simultaneously with the same batch developed protective antibodies. In conclusion, HIV-positive patients and their providers should be informed about HAV vaccine failure, and post-immunization serologies to hepatitis should be considered to evaluate immunization response. Alternative approaches to develop immunity are needed for non-responders.

Hepatitis A: Epidemiology and prevention in developing countries

Hepatitis A is the most common form of acute viral hepatitis in the world. Major geographical differences in endemicity of hepatitis A are closely related to hygienic and sanitary conditions and other indicators of the level of socioeconomic development. The anti-hepatitis A virus (HAV) seroprevalence rate is presently decreasing in many parts of the world, but in less developed regions and in several developing countries, HAV infection is still very common in the first years of life and seroprevalence rates approach 100%. In areas of intermediate endemicity, the delay in the exposure to the virus has generated a huge number of susceptible adolescents and adults and significantly increased the average age at infection. As the severity of disease increases with age, this has led to outbreaks of hepatitis A. Several factors contribute to the decline of the infection rate, including rising socioeconomic levels, increased access to clean water and the availability of a hepatitis A vaccine that was developed in the 1990s. For populations with a high proportion of susceptible adults, implementing vaccination programs may be considered. In this report, we review available epidemiological data and implementation of vaccination strategies, particularly focusing on developing countries.

Decline in HAV-associated fulminant hepatic failure and liver transplant in children in Argentina after the introduction of a universal hepatitis A vaccination program

INTRODUCTION

Hepatitis A virus (HAV) infection is a vaccine-preventable disease. The most severe complication in children is fulminant hepatic failure (FHF), estimated to occur in 0.4% of cases; patients with FHF often require a liver transplant (LT). Following another outbreak of HAV infection in Argentina during 2003-2004, a one-dose HAV universal immunization (UI) program was started in 2005, resulting in a reduction in the incidence of HAV infection. We have investigated the impact of HAV UI on the trends in the occurrence of FHF and LT in children.

METHODS

All pediatric cases of FHF admitted to four pediatric centers in Buenos Aires during March 1993-July 2005 were retrospectively reviewed, and data of cases during August 2005-December 2008 were collected. Information about demography, HAV infections and vaccination status, diagnostic data for FHF using the Pediatric Acute Liver Failure criteria, clinical laboratory results, encephalopathy, the severity of liver disease using the Pediatric End Stage Liver Disease score, assessment of patients on the LT waiting list using King's College Criteria for LT, treatment given for FHF (pre- and post-transplant), and clinical outcome were collected using a case report form. The frequency and outcomes of HAV-associated FHF and LT cases before and after UI were analyzed.

RESULTS

During the pre-immunization period, March 1993-July 2005, 54.6% (N = 165) of FHF cases were caused by HAV; HAV-associated FHF cases peaked during 2003-2004. During the post-immunization period, August 2005-December 2008, only 27.7% (N = 18) of FHF cases were caused by HAV infection; only one of these patients had received the HAV vaccine (one dose only). The number of HAV-associated FHF cases decreased from 2005, and no cases were reported from November 2006-December 2008. Multivariate analyses showed that the association of FHF with HAV infection rather than other etiologies decreased with increasing age (P = 0.03), UI against HAV (P = 0.002), and anti-actin antibodies (P = 0.002), and increased with increasing weight (P = 0.0004).

CONCLUSIONS

The number of children with HAV-associated FHF in Argentina has strongly decreased since the initiation of the UI program. Further monitoring is required to confirm the long-term health and economic benefits of UI against HAV infection.

Strategy for hepatitis A seroprevalence survey in a population of young people

In the present research a novel operative strategy of health surveillance with a reduced number of serologic tests is proposed. The approach consists to identify sub-populations with high predictable serological profile that makes the serological tests unnecessary. The study is focused on assays done to detect the response against hepatitis A, which in Italy displays low/intermediate endemicity. Receiver operating characteristics analysis performed on data from documented and self-reported vaccination information of a cohort of students from Padua University Medical School confirmed that anti-hepatitis A antibodies measurement might be avoided in subjects younger than 30 years with negative documented or self-reported history of vaccination or subjected to current vaccination schedule.