Waning of anti-HAV immunity in Shijiazhuang prefecture, Hebei province, China: A comparison of seroprevalence between 1992 and 2011

The Shifting Epidemiology of Hepatitis A in the World Health Organization Western Pacific Region

Within the past few decades, improvement in sanitation and economic growth has driven a changing epidemiology of hepatitis A in the Western Pacific Region (WPR) of the World Health Organization (WHO). In this review, we gathered available published information on hepatitis A epidemiology of the countries in the WPR and reviewed the trends reported in the literature from the years 2000 to 2021. Many countries have shifted from high endemicity to low endemicity. Moreover, the administration of the hepatitis A vaccine among children in recent years has shifted disease susceptibility to the older population. Seroprevalence among children has decreased in most countries, while nearly 100% seropositivity is seen in mid adulthood. This is contrary to the epidemiology seen in previous decades when most children achieved immunity by age ten. This also presents a paradox in that better living conditions have caused more vulnerability to the older age groups who are at higher risk for severe disease. Given these trends, we recommend vaccination of vulnerable populations such as the older age groups and inclusion of the hepatitis A vaccine in government immunization programs.

Exploration of a new hepatitis a surveillance system in Beijing, China: based on molecular epidemiology

Background

The incidence of hepatitis A virus (HAV) infection is low in Beijing, China, but the risk of outbreaks still exists. It is difficult to identify possible sources of infection among sporadic cases based on a routine surveillance system. Therefore, a more effective surveillance system needs to be established.

Methods

The epidemiological data of hepatitis A were obtained from a routine surveillance system. Patients with HAV confirmed at the local hospitals were asked to complete a questionnaire that included additional case information and possible sources of infection. Serum and fecal specimens were also collected for testing HAV RNA by polymerase chain reaction. In addition, the 321-nucleotide segment of the VP1/2A junction region was sequenced to determine the HAV genotype.

Results

In 2019, 110 HAV cases were reported in Beijing, with an incidence rate of 0.51/100,000. 61(55.5%) of these patients were male. The greatest proportion of these patients were aged from 30 to 60 years. The rate was lower in suburban and rural areas compared to urban areas. Contaminated food consumption, particularly seafood consumption, was the primary potential source of infection. Among the 16 specimens of confirmed HAV cases that could be sequenced, 93.8% were HAV IA, and 6.3% were HAV IB. In addition, the samples collected from all HAV sequences in this investigation showed 89.4–100% nucleotide homology. Two groups (each with three sporadic cases) showed 100% nucleotide homology. The three sporadic cases in one group had the same possible source of infection: contaminated salad with raw vegetables and seafood. In the other group, the three sporadic cases did not have an epidemiological connection.

Conclusions

In a low HAV prevalent area, such as in Beijing, incorporating molecular epidemiology into the routine surveillance system could help inform possible clusters of outbreaks and provide support for earlier control of HAV transmission. Nevertheless, increased sampling from detected cases and improved specimen quality are needed to implement such a system.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06872-4.

Changing Epidemiology of Hepatitis A in China: Evidence From Three National Serological Surveys and the National Notifiable Disease Reporting System

BACKGROUND AND AIMS

China has conducted surveillance for hepatitis A since 1990, and hepatitis A was highly-to-intermediately endemic in 1992 when a Chinese hepatitis A vaccine (HepA) was licensed and introduced as a family-pay vaccine. In 2008, HepA was introduced into the Expanded Program on Immunization as a free childhood vaccine.

APPROACH AND RESULTS

Three nationally representative surveys conducted in 1992, 2006, and 2014 assessed hepatitis B serology. The 1992 survey included hepatitis A virus (HAV) serology, and we tested sera from the 2006 and 2014 surveys for HAV antibodies. We used surveillance, seroprevalence, and vaccination status data to describe the changing epidemiology of hepatitis A in China from 1990 through 2014. Before HepA licensure, anti-HAV seroprevalence was 60% at 4 years of age, 70% at 10 years, and 90% at 59 years; incidence was 52/100,000 and peaked at 4 years. In 2006, after >10 years of private sector vaccination, HepA coverage was <30% among children <5 years, and incidence was 5.4/100,000 with a peak at 10 years. In 2014, coverage was >90% among children under 5 years; incidence was 1.9/100,000. Individuals born before the national introduction of HepA (1988-2004) had lower anti-HAV seroprevalence than earlier and later birth cohorts.

CONCLUSIONS

The incidence of hepatitis A declined markedly following HepA introduction and improvement of sanitation and hygiene. The emerging epidemiology is consistent with disease-induced immunity having been replaced by vaccine-induced immunity, resulting in a low incidence of hepatitis A. Catch-up HepA campaigns to close the immunity gap among the 1998-2004 birth cohorts should be considered.

Changes in seroprevalence of hepatitis A after the implementation of universal childhood vaccination in Shandong Province, China: A comparison between 2006 and 2014

OBJECTIVES

The hepatitis A vaccine (HepA) has been included in the national expanded program on immunization (EPI) in China since 2008. This study was performed to evaluate the change in dynamics of the seroepidemiology of hepatitis A virus (HAV) before and after the introduction of the program.

METHODS

The trends in seroepidemiology of anti-HAV antibodies were examined in Shandong Province, China, drawing on two population-based samples of persons aged 1-59 years, one obtained in the year 2006 (n = 6682) and the other in 2014 (n = 5095).

RESULTS

A dramatic increase in seroprevalence of anti-HAV antibodies from 30.76% (95% confidence interval (CI) 26.24-35.28%) to 77.46% (95% CI 74.04-80.87%) among children aged 1.5-7 years (born after HepA was recommended for routine childhood immunization), as well as an increase from 35.32% (95% CI 29.31-41.33%) to 66.69% (95% CI 55.59-77.80%) in subjects aged 8-14 years, was observed in 2014 when compared with 2006. By contrast, a decline in seroprevalence among subjects aged 15-29 years, as seen particularly in those 20-29 years of age, from 85.72% (95% CI 80.29-91.14%) to 69.24% (95% CI 62.02-76.45%), was found in this study. There was no statistically significant difference in seroprevalence between 2006 and 2014 among the subjects older than 30 years of age.

CONCLUSIONS

The national HepA routine immunization program has had a positive effect, leading to an increase in anti-HAV seroprevalence among children in Shandong Province, China. More attention should be paid to young adults in the province.

Changing epidemiological characteristics of Hepatitis A and warning of Anti-HAV immunity in Beijing, China: a comparison of prevalence from 1990 to 2017

Backgroud: Beijing was hyper-endemic for hepatitis A until the 1990s and has been vaccinating against hepatitis A since 1994. The objective is to study the epidemiology and changes of antibody level of hepatitis A from 1990 to 2017.

METHODS

A multistage randomized cluster sampling serological cross-sectional study was conducted in individuals over one year old in 1992, 2006 and 2014 in Beijing. Venous blood samples were collected to test anti-HAV antibody. The incidence data of hepatitis A were obtained from National Notifiable Disease Reporting System (NNDRS) and CDC statistics in Beijing. The vaccination data of hepatitis A immunization were acquired from Beijing Immune Information System.

RESULTS

From 1990 to 2017, the reported incidence rate of HAV in Beijing declined from 59.41/100,000 in 1990 to 0.80/100,000 in 2017. The average age of HAV infection was postponed from individuals under 20 years old to individuals over 20 years old. After hepatitis A vaccine was introduced to Beijing, the outbreak of hepatitis A decreased sharply. Adjusted anti-HAV positive rate in general population was 68.23%, 81.73% and 82.47% respectively in 1992, 2006 and 2014. Due to hepatitis A vaccination conducted in children, the anti-HAV positive rate in individuals under 20 years old increased from 1992 to 2014, while in individuals over 20, this rate was barely changed. The coverage rate in target population was higher than 99% after hepatitis A vaccine was integrated into Expanded Program on Immunization (EPI).

CONCLUSION

Incidence rate of hepatitis A in Beijing has decreased dramatically from 1990 to 2017. Hepatitis A vaccine plays an important role in protecting individuals under 20 years old. A higher proportion of adults will be susceptible to hepatitis A virus due to the decay of antibodies as they grow up from childhood to adulthood, which may result in possible outbreak of hepatitis A.

Immune memory at 17-years of follow-up of a single dose of live attenuated hepatitis A vaccine

BACKGROUND

In recent years, hepatitis A virus (HAV) infection has declined considerably in China, associated with wide deployment of HAV vaccines and improvement in socio-economic indicators. Towards the elimination of HA in the country, we assessed the duration and characteristics of immunity conferred by the widely used, locally manufactured HAV vaccine.

METHODS

This is a longitudinal cohort study that followed recipients of a live attenuated HAV vaccine 17 years after the initial administration. Blood samples were collected from participants pre- and two-week post-booster HAV vaccine dose. Serum anti-HAV antibody was measured by ELISA method. Memory B and T cells were determined by ELISPOT and Flow Cytometry assays, respectively.

RESULTS

A robust anamnestic response was observed two-week post-challenge. Both HAV-specific memory B cell and T cells remained, and responded quickly when re-encountering HAV. The magnitude of recall responses was present, regardless of the status of the serum anti-HAV antibody pre-booster.

CONCLUSIONS

We demonstrated long-term immunity from the live attenuated HAV vaccine, including antibody persistence and immunological memory. Considering the conditions that make elimination of infectious diseases feasible, following polio, hepatitis A could be targeted for elimination in China.

Persistence of seropositivity among persons vaccinated for hepatitis A during infancy by maternal antibody status: 15-year follow-up

The effect of passively transferred maternal antibody to hepatitis A virus (anti-HAV) on the duration of seropositivity after hepatitis A vaccination during infancy and early childhood is unclear. We obtained levels of anti-HAV at intervals through age 15-16 years among three groups of Alaskan Native children who initiated a two-dose inactivated hepatitis A vaccination series at ages 6 months (group 1), 12 months (group 2), and 15 months (group 3), each group randomized according to maternal anti-HAV status. Seropositivity (anti-HAV ≥20 mIU/mL) 30 years after the second vaccine dose among the three groups was predicted using a random effects model. One hundred eighty-three children participated in the study; follow-up did not differ significantly by vaccine group or maternal anti-HAV status. Although the frequency of seropositivity among all participants through age 10 years was high (100% among groups 2 and 3 and >90% among group 1), there was a decrease thereafter through age 15-16 years among group 1 children, who initiated vaccination at age 6 months (50%-75%), and among maternal anti-HAV-positive children in groups 2 and 3 (67%-87%), who initiated vaccination at ages 12 months and 15 months, respectively. Nonetheless, the model indicated that anti-HAV seropositivity should persist for ≥30 years after vaccination in 64% of all participants; among those seropositive at age 15-16 years, 84% were predicted to remain so for ≥30 years.

CONCLUSION

Most children vaccinated during early childhood available for sampling maintained seropositivity through age 15-16 years; however, seropositivity was less frequent among those starting vaccination at age 6 months and among maternal antibody-positive participants who started vaccination at age 12 months or 15 months; overall, our findings support current vaccine recommendations and continued follow-up of this cohort.

Progress Toward Eliminating Hepatitis A Disease in the United States

Hepatitis A virus (HAV) disease disproportionately affects adolescents and young adults, American Indian/Alaska Native and Hispanic racial/ethnic groups, and disadvantaged populations. During 1996-2006, the Advisory Committee on Immunization Practices (ACIP) made incremental changes in hepatitis A (HepA) vaccination recommendations to increase coverage for children and persons at high risk for HAV infection. This report examines the temporal association of ACIP-recommended HepA vaccination and disparities (on the absolute scale) in cases of HAV disease and on seroprevalence of HAV-related protection (measured as antibody to HAV [anti-HAV]). ACIP-recommended childhood HepA vaccination in the United States has eliminated most absolute disparities in HAV disease by age, race/ethnicity, and geographic area with relatively modest ≥1-dose and ≥2-dose vaccine coverage. However, the increasing proportion of cases of HAV disease among adults with identified and unidentified sources of exposure underscores the importance of considering new strategies for preventing HAV infection among U.S. adults. For continued progress to be made toward elimination of HAV disease in the United States, additional strategies are needed to prevent HAV infection among an emerging population of susceptible adults. Notably, HAV infection remains endemic in much of the world, contributing to U.S. cases through international travel and the global food economy.