Effectiveness of hepatitis A vaccine in a former frequently affected community: 9 years' followup after the Monroe field trial of VAQTA

Present and future management of viral hepatitis

Viral hepatitis can result in important morbidity and mortality, with its impact on health conditioned by the specific type of hepatitis, the geographical region of presentation and the development and access to new drugs, among other factors. Most acute presentation forms are self-limiting and may even go unnoticed, with just a small percentage of cases leading to acute liver failure that may necessitate transplantation or even cause the death of the patient. However, when they become chronic, as in the case of hepatitis B virus and C virus, unless they are diagnosed and treated adequately they may have severe consequences, like cirrhosis or hepatocarcinoma. Understanding of the mechanisms of transmission, the pathogenesis, the presence of vaccinations and the development over recent years of new highly-efficient, potent drugs have meant that we are now faced with a new scenario in the management of viral hepatitis, particularly hepatitis B virus and hepatitis C virus. The spectacular advances in hepatitis C virus treatment have led the World Health Organization to propose the objective of its eradication by 2030. The key aspect to achieving this goal is to ensure that these treatments reach all the more vulnerable population groups, in whom the different types of viral hepatitis have a high prevalence and constitute a niche that may perpetuate infection and hinder its eradication. Accordingly, micro-elimination programs assume special relevance at the present time.

The History of Hepatitis A

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Hepatitis A virus seroepidemiology of elementary school children in New Taipei City in Taiwan

BACKGROUND

To establish the seroepidemiologic data of hepatitis A virus (HAV) vaccine-preventable HAV diseases among school children (7-12 years old) attending elementary schools in New Taipei City, Taiwan. This is a pilot study of an ongoing nationwide study, and will be the reference for a national immunization program.

METHODS

The school children were selected for samplings, based on a multistage stratified sampling method that included 14 variables (4 socioeducational variables, 4 socioeducational variables, and 6 medical facilities' variables). The 29 administrative districts of New Taipei City were categorized into five strata. In total, 936 school children from 14 schools were recruited and bled for the serologic tests of HAV by enzyme-linked immunosorbent assay method.

RESULTS

The seropositive rate for HAV was 8.33% among the 936 children. From each school, the difference in the seropositive rate for HAV ranged 0-18.75%. There was no significant difference between each stratum (p = 0.059) or grade (p = 0.570); however, there was a difference between schools in the first stratum (p = 0.033) that was associated with different vaccination rates. This study also revealed a significantly greater seropositive rate in the vaccination group (p < 0.001) and in females (p = 0.02).

CONCLUSION

The seropositive rate for the HAV was <10% and was mostly associated with the vaccination status. Because of the low HAV vaccination rate and low seropositive rate for the HAV, an effective hepatitis A vaccine is a useful tool to prevent HAV infection. It is worthy to discuss whether to include the HAV vaccine as part of a routine vaccination program in Taiwan.

Seroprevalence of anti-hepatitis a antibody among 1 - 15 year old children in kashan-iran

BACKGROUND

Worldwide, hepatitis A is a common infection during childhood especially in developing countries. It can cause severe complications in adults and patients with underlying diseases.

OBJECTIVES

This study was performed to determine the seroprevalence of hepatitis A in 1 - 15 year-old children of Kashan.

PATIENTS AND METHODS

This cross-sectional study was performed on 666 one to fifteen year-old children from health-care centers in Kashan city during 2012. Total antibodies against hepatitis A were measured in sera by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Totally, 3.9% of children were seropositive. Mean number of family members was 3.92 ± 0.89. There was no difference in seroprevalence of hepatitis A relative to sex, family size, mean age and age groups.

CONCLUSIONS

In this city, a great proportion of children are susceptible to hepatitis A and it's complications at an older age. This decrease in seropositivity may be caused by elevated hygien level. According to our results hepatitis A vaccination is recommended at early childhood such as that of other regions where low prevalence of hepatitis A infection is found.

Immune response to hepatitis A vaccination in HIV-infected men in Greece

HIV-infected patients are at increased risk for acquiring hepatitis A virus (HAV) infection. We evaluated the seroconversion rate (anti-HAV antibodies ≥ 20 mIU/ml) and the geometric mean antibody titres (GMTs) in a group of 351 HIV infected men, who had received two doses of a hepatitis A vaccine. We analysed blood samples collected at one, six, 12 and 18 months following the administration of the second dose of the vaccine. The seroconversion rate one month after the second dose of the vaccine was 74.4% (260/351). At month 18 after the end of vaccination, 56.1% of the subjects remained seropositive. GMTs were 315, 203, 153 and 126 mIU/ml at months 1, 6, 12, and 18, respectively. Logistic regression revealed that the CD4 count is the only factor affecting response to vaccination (P = 0.019). A higher response rate and higher GMTs were observed in patients with CD4 counts ≥ 500 cells/mm(3) (76.6%) than in patients with CD4 counts 200-499 cells/mm(3). In conclusion, even in patients with near-normal CD4 counts, the response to the hepatitis A vaccine is impaired.

Viral hepatitis: global goals for vaccination

In countries where hepatitis A is highly endemic, exposure to hepatitis A virus (HAV) is almost universal before the age of 10 years, and large-scale immunization efforts are not required. In contrast, in areas of intermediate endemicity or in transition from high to intermediate endemicity, where transmission occurs primarily from person to person in the general community (often with periodic outbreaks), control of hepatitis A may be achieved through widespread vaccination programmes. Hepatitis B virus (HBV) is one of the world's most widespread infectious agents and the cause of millions of infections each year. Between 500,000 and 700,000 people die each year from chronic infection-related cirrhosis, hepatocellular carcinoma (HCC) or from acute hepatitis B. Hepatitis B vaccine provides protection against infection and its complications including liver cirrhosis and HCC. It is therefore, the first vaccine against a cancer, the first vaccine protecting from a sexually transmitted infection, and the first vaccine against a chronic disease ever licensed. Control and significant reduction in incidence of new HBV infections as well as hepatocellular carcinoma has repeatedly been reported in countries in East Asia (i.e. Taiwan) and Africa (i.e. The Gambia). Two experimental vaccines against hepatitis E have been developed; one of them has been recently licensed but is not yet widely available. Attempts to develop a hepatitis C vaccine were so far unsuccessful.

Long-term durability of immune responses after hepatitis A vaccination among HIV-infected adults

BACKGROUND

Vaccination provides long-term immunity to hepatitis A virus (HAV) among the general population, but there are no such data regarding vaccine durability among human immunodeficiency virus (HIV)-infected adults.

METHODS

We retrospectively studied HIV-infected adults who had received 2 doses of HAV vaccine. We analyzed blood specimens taken at 1 year, 3 years, and, when available, 6-10 years postvaccination. HAV immunoglobulin G (IgG) values of ≥10 mIU/mL were considered seropositive.

RESULTS

We evaluated specimens from 130 HIV-infected adults with a median age of 35 years and a median CD4 cell count of 461 cells/mm(3) at or before time of vaccination. Of these, 49% had an HIV RNA load <1000 copies/mL. Initial vaccine responses were achieved in 89% of HIV-infected adults (95% confidence interval [CI], 83%-94%), compared with 100% (95% CI, 99%-100%) of historical HIV-uninfected adults. Among initial HIV-infected responders with available specimens, 90% (104 of 116; 95% CI, 83%-95%) remained seropositive at 3 years and 85% (63 of 74; 95% CI, 75%-92%) at 6-10 years. Geometric mean concentrations (GMCs) among HIV-infected adults were 154, 111, and 64 mIU/mL at 1, 3, and 6-10 years, respectively, compared with 1734, 687, and 684 mIU/mL among HIV-uninfected persons. Higher GMCs over time among HIV-infected adults were associated with lower log(10) HIV RNA levels (β = -.12, P = .04).

CONCLUSIONS

Most adults with well-controlled HIV infections had durable seropositive responses up to 6-10 years after HAV vaccination. Suppressed HIV RNA levels are associated with durable HAV responses.

Factors associated with hepatitis A vaccination receipt in one-year-olds in the state of Michigan

The objectives of this study were to determine factors associated with hepatitis A vaccination and to assess overall hepatitis A vaccination coverage levels among one-year-olds in Michigan. The study population was the first hepatitis A vaccination-eligible birth cohort (n = 134 226) enrolled in the Michigan Care Improvement Registry (MCIR) after 2006 recommendations were made to routinely vaccinate all one-year-olds. All children whose first birthday occurred on or between May 1, 2006 and April 31, 2007 were included in the study population. Racial/ethnic minorities had increased odds of receiving the hepatitis A vaccination in Michigan, and Medicaid and WIC status modified this relationship. Fully understanding these relationships will be useful in targeting vaccination outreach and education programs.

Seroepidemiology of hepatitis A virus in Kuwait

AIM: To find the current seroepidemiology of hepatitis A virus (HAV) in Kuwait.

METHODS: A total of 2851 Kuwaitis applying for new jobs were screened.

RESULTS: HAV-positive cases were 28.8%; 59% were males and 41% were females. The highest prevalence was in the Ahmadi area. High prevalence was among the group of non-educated rather than educated parents. This is the first study in Kuwait demonstrating the shifting epidemiology of HAV.

CONCLUSION: This study reflects the need of the Kuwaiti population for an HAV vaccine.

Field effectiveness of vaccination against tick-borne encephalitis

Tick-borne encephalitis (TBE) is a vaccine-preventable disease caused by a flavivirus (TBE virus) that is endemic in many European countries and large parts of Central and Eastern Asia. In Europe, highly purified formalin-inactivated whole virus vaccines are in widespread use, but the vaccination coverage differs significantly between countries with TBE endemicity. Austria presents an exceptional situation because 88% of the total population have a history of TBE vaccination, with 58% being regularly vaccinated within the recommended schedule. In this study, we investigated the field effectiveness of TBE vaccination in Austria for the years 2000-2006 in different age groups on the basis of the documented numbers of hospitalized cases in unvaccinated and vaccinated people and the sizes of these population groups as revealed by representative inquiries. We show that the overall effectiveness in regularly vaccinated persons is about 99% with no statistically significant difference between age groups. It is at least as high after the first two vaccinations, i.e. before the completion of the basic vaccination scheme by a third vaccination, but is significantly lower (about 95%) in those with a record of irregular vaccination. Our data confirm the excellent performance of TBE vaccine under field conditions and provide evidence that, in Austria, about 2800 cases were prevented by vaccination in the years 2000-2006.

An outbreak of hepatitis A among homeless drug users in Rotterdam, The Netherlands

From the end of January to mid-June 2004 (weeks 5-24) a hepatitis A virus (HAV) outbreak occurred among a homeless and drug user community in Rotterdam, The Netherlands. To prevent further spread of the virus within this group and to the general population, the Municipal Health Service of Rotterdam organized a mass vaccination campaign during which 83% (1,515/1,800) of the homeless people were vaccinated. As part of a national HAV typing study, blood and/or fecal samples of 30 Rotterdam HAV IgM+ patients who fell ill during the period of 1 September 2003-1 December 2004 were tested. The tests included RT-PCR and sequencing at the VP3-VP1 and VP1-P2a regions of the HAV genome. It was found that 12 homeless people, one family member of a homeless person and two people without a known risk were infected with a unique subtype 3a strain. Four of the homeless patients became ill after vaccination and were probably infected at the time. This study shows that Dutch homeless people and drug users involved in HAV outbreaks should be offered HAV vaccine actively to prevent further spread of the infection. Furthermore, it was shown by molecular techniques that the unique subtype 3a strain was not found before the Rotterdam outbreak or afterwards, indicating that the mass vaccination campaign was successful.

Hepatitis A booster vaccination: is there a need?

Hepatitis A is one of the most common vaccine-preventable infectious diseases in the world. Effective vaccines against hepatitis A have been available since 1992, and they provide long-term immunity against the infection. However, there is no worldwide consensus on how long protection will last or whether there will be a need for hepatitis A virus (HAV) booster vaccinations in the future. In most countries, booster-vaccination policy is guided by manufacturers' recommendations, national authorities, or both. In June, 2002, a panel of international experts met to review the long-term immunogenicity and protection conferred by HAV vaccine in different population groups. Data have shown that after a full primary vaccination course, protective antibody amounts persist beyond 10 years in healthy individuals, and underlying immune memory provides protection far beyond the duration of anti-HAV antibodies. The group concluded that there is no evidence to lend support to HAV booster vaccination after a full primary vaccination course in a healthy individual. However, further investigations are needed before deciding if boosters can be omitted in special patient-groups.

Prevention of hepatitis A by vaccination

Inactivated hepatitis A vaccines have been available for more than a decade. Characteristics of the vaccines, comparative data among different formulations and the possibility of combination and association with other vaccines are reviewed in this article. Hepatitis A vaccines show high immunogenicity with different schedules and associations, induce long-term protection irrespective of timing of booster dose, and present an excellent safety profile. Pre-exposure efficacy has been demonstrated in large trials and postexposure protection has been described in family contacts of acute cases. The recommendations for the use of hepatitis A vaccines for immunisation campaigns and for targeted groups, such as travellers and people at risk for occupational and iatrogenic exposure or lifestyle behaviours, are discussed. Aspects related to economic analysis of vaccination strategies are also considered.

Long-term immunogenicity and protective efficacy of a live attenuated hepatitis A vaccine (LA-1 strain)

AIM

To evaluate the long-term protective efficacy following a large scale immunization with a live attenuated hepatitis A vaccine (the LA-1 strain) and immune persistence of the vaccine with different immunization schedules.

METHODS

A randomized controlled double-blind study was conducted in 212 985 children between 1.5 and 10 years of age from 8 counties in Guangxi province (10 0735 in vaccine group and 112 250 in control group). Vaccine group was received one dose of HAV vaccine of 10^6.75 TCID₅₀ (LA-1 strain, China). Surveillance of the incidence of hepatitis A in the two groups was started 1 month after vaccination. To evaluate the persistence of antibodies, 156 children of 6-9 years old with hepatitis A antibody negative were divided into 3 groups with equalities in age and sex. Group A was given one dose of the vaccine, Group B and C were immunized according to 0, 6 and 0, 12 schedules respectively. During follow-up of every individual, the blood specimens were collected at 6, 12, 24 and 36 months after immunization in Group A and 12, 24 and 36 months after first dose and 1 month after second dose in Group B and C. Anti-HAV levels were expressed as GMTs in mIU/ml by serial immunoglobulin dilutions (WHO standard) and HAVAB-Imx kit (Abbott Lab, USA).

RESULTS

During a follow-up for 36 months, 71 cases of symptomatic HAV infection were found in the control and 2 in the vaccine group (63.25/10⁶vs 1.99/10⁶ respectively). The protective efficacy was estimated at 96.85% with 95% lower confidence limit of 92.4%. The antibody positive rate in Group A after 6-24 months was 88.6-91.4%, the GMT was 105-106 mIU/ml, but each of those decreased to 80.0% and 99.20 mIU/ml after 36 months. GMT reached to the top in Group B and C1 month after the second dose, 1024.63 mIU/ml and 3 463.21 mIU/ml respectively. But during the time from top GMT to 24th month, the GMT of Group B and C decreased rapidly to about 59.4% and 83% respectively, and it continually declined slowly at 36^th month to 459.68 mIU/ml and 506.23 mIU/ml, which were 6% and 15% lower than that at 24^th month. It showed that the antibody level in Group B and C after 2 doses were significantly higher than that in Group A from beginning to end, at 36th month the GMT of Group B and C were 4.6 times and 5.1 times to that of Group A, and the antibody positive rate (97%) was higher than that of Group A (80%) at the same time.

CONCLUSION

A single dose of live attenuated hepatitis A vaccine can come into being high and persistent protection against hepatitis A. Booster dose induces an immune response which persists for at least three years in 97% of the subjects. The high GMT still present at month 36 predicts a long-term persistence of antibody.