Hepatitis B vaccination coverage among Asian and Pacific Islander children--United States, 1998

Asian and Pacific Islander (API) children in the United States have high rates of hepatitis B virus (HBV) infection (1-3). To prevent these infections, hepatitis B vaccination has been recommended for these children since the vaccine was first licensed by the Food and Drug Administration in 1981 (4). Recommendations have included universal hepatitis B vaccination of API infants beginning in 1990 and catch-up vaccination for API children aged <7 years (5). These recommendations were reinforced in 1991 when hepatitis B vaccination was recommended for all infants, particularly in populations such as API children with high rates of early childhood HBV infection (6). In 1995, vaccination was recommended for unvaccinated API children aged <11 years and catch-up vaccination for children aged 11-12 years who had not received hepatitis B vaccine (HepB) (7). Series completion among API children aged 19-35 months increased from 39% in 1994 to 88% in 1997 (8). However, among older API children, hepatitis B vaccination coverage was 10% in 1995 (7). In 1998, to examine trends in hepatitis B vaccination catch-up coverage among API children born before 1994, surveys were conducted in six U.S. cities. This report summarizes the results of the surveys, which indicate varying coverage among API children and suggest a need for continued focused vaccination programs for this population.     

Modelling of COVID-19 vaccination strategies and herd immunity,in scenarios of limited and full vaccine supply in NSW,Australia

Several vaccines for SARS-CoV-2 are expected to be available in Australia in 2021. Initial supply is limited and will require a judicious vaccination strategy until supply is unrestricted. If vaccines have efficacy as post-exposure prophylaxis (PEP) in contacts, this provides more policy options. We used a deterministic mathematical model of epidemic response with limited supply (age-targeted or ring vaccination) and mass vaccination for the State of New South Wales (NSW) in Australia. For targeted vaccination, the effectiveness of vaccinating health workers, young people and older adults was compared. For mass vaccination, we tested varying vaccine efficacy (VE) and distribution capacities. With a limited vaccine stockpile enough for 1 million people in NSW, if there is efficacy as PEP, the most efficient way to control COVID-19 will be ring vaccination, however at least 90% of contacts per case needs to be traced and vaccinated. Health worker vaccination is required for health system resilience. Age based strategies with restricted doses make minimal impact on the epidemic, but vaccinating older people prevents more deaths. Herd immunity can only be achieved with mass vaccination. With 90% VE against all infection, herd immunity can be achieved by vaccinating 66% of the population. A vaccine with less than 70% VE cannot achieve herd immunity and will result in ongoing risk of outbreaks. For mass vaccination, distributing at least 60,000 doses per day is required to achieve control. Slower rates of vaccination will result in the population living with COVID-19 longer, and higher cases and deaths.     

Measles immunity in young Australian adults.

Previous state-based serosurveys and recent outbreaks have indicated that young adults may be at risk of measles. To provide a national picture of immunity in adults, we tested 2126 sera from 19-49 year olds that had been opportunistically collected from laboratories across Australia, between July 1996 and November 1998. Sera were stratified into age groups based on expected levels of immunity. Sample numbers were proportional to the population size in each State and Territory. Immunity was determined using an anti-measles IgG enzyme immunoassay (EIA) according to the manufacturer's instructions. Results were compared with those on sera from 2 groups of 1-18 year olds; one group collected before the Measles Control Campaign (conducted in the second half of 1998) and the other group collected after the Campaign. Immunity was highest (98.3%) in subjects aged at least 30 years (born before 1968) reflecting greater exposure to the measles virus in these older subjects. Immunity was lowest in those aged 1-6 years (born in 1994-8; 83.6%) and 18-22 years (born in 1974-80; 88.9%). The relatively low level of immunity in 18-22 year olds is probably due to lower vaccination coverage in this group compared with younger cohorts (aged 6-17 years). These results indicate the ongoing need to improve vaccine uptake in infants and suggest that a vaccination campaign targeting young adults would be beneficial.     

Measles vaccine effectiveness in Central Australian Aboriginal children vaccinated at or after eight months of age

An outbreak of measles in central Australia in 1994 provided the first opportunity to evaluate the effectiveness of the measles vaccine given to Aboriginal children at nine months of age since 1984. Children eligible for the study that was conducted in one community in the region were aged between nine months and 10 years. Eight of the 109 eligible children developed measles. The only unvaccinated child also developed measles. Vaccination failures occurred in 7.8% (6/77) of children vaccinated between eight and 11 months of age and in 3.2% (1/ 31) vaccinated after 11 months of age. Overall vaccine effectiveness was 93.5%. The level of vaccine uptake in central Australia is high and the last region-wide outbreak before 1994 occurred in 1981-82. If the age of vaccination against measles is to be determined by the average age of infection; the age of vaccination should now be raised to 12 months of age; this is the age at which Aboriginal children in all other states and all children in Australia are vaccinated.     

云南省华宁县769例健康人群乙型肝炎疫苗免疫水平

目的掌握云南省华宁县健康人群乙型肝炎（乙肝）病毒感染状况及免疫水平,评价乙肝疫苗接种及纳入计划免疫的效果,为提高我县免疫规划工作提供科学依据。方法根据《全国人群乙肝等有关疾病血清学调查方案》的要求,结合华宁县具体情况,按容量比例概率抽样法（PPS）随机抽取769例健康人群,采用酶联免疫吸附试验（ELISA）检测乙肝表面抗原及抗体。结果调查的769例健康人群中乙肝疫苗接种率为77.11%,乙肝表面抗原阳性率为0.39%、乙肝表面抗体阳性率为75.81%,乙肝疫苗接种保护率为94.56%。不同乡镇、不同年龄组间乙肝疫苗接种率、乙肝表面抗体阳性率差异有统计学意义;性别间差异无统计学意义。结论华宁县健康人群乙肝疫苗接种保护率较高,乙肝疫苗免疫效果显著,还要加强重点人群的乙肝疫苗接种工作,巩固乙肝免疫效果。     

Risks associated with hepatitis infection in patients with hepatitis C and opportunities for prophylaxis

Patients with chronic hepatitis C remain at risk of acquiring hepatitis A infection and additional liver injury. The estimated risk of HAV infection in HCV patients is similar to that in general population but may be higher in anti-HCV positive drug users. Despite some controversies available data indicate that hepatitis A infection is associated with much higher incidence of hepatitis fulminans and mortality rate in individuals with pre-existing liver disease. In Poland about 60% of all HCV-infected adults have natural immunity to HAV, however majority of those under 35 years majority remains unprotected. Currently available inactivated HAV vaccine proved to be highly immunogenic and safe in patients with hepatitis C. The vaccination should be administered in each unprotected patient upon diagnosis of HCV infection.     

Seroepidemiology of hepatitis A and hepatitis B virus in Luxembourg

A prospective seroepidemiological survey was carried out in Luxembourg in 2000-2001 to determine the antibody status of the Luxembourg population against hepatitis A virus (HAV) and hepatitis B virus (HBV). One of the objectives of this survey was to assess the impact of the hepatitis B vaccination programme, which started in May 1996 and included a catch-up campaign for all adolescents aged 12-15 years. Venous blood from 2679 individuals was screened for the presence of antibodies to HAV antigen and antibodies to hepatitis B surface antigen (anti-HBs) using an enzyme immunoassay. Samples positive for anti-HBs were tested for antibody to hepatitis B core antigen (anti-HBc) using a chemiluminiscent microparticle immunoassay to distinguish between individuals with past exposure to vaccine or natural infection. The estimated age-standardized anti-HAV seroprevalence was 42.0% [95% confidence interval (CI) 39.8-44.1] in the population >4 years of age. Seroprevalence was age-dependent and highest in adult immigrants from Portugal and the former Yugoslavia. The age-standardized prevalence of anti-HBs and anti-HBc was estimated at 19.7% (95% CI 18.1-21.3) and 3.16% (95% CI 2.2-4.1) respectively. Anti-HBs seroprevalence exceeding 50% was found in the cohorts targeted by the routine hepatitis B vaccination programme, which started in 1996. Our study illustrates that most young people in Luxembourg are susceptible to HAV infection and that the hepatitis B vaccination programme is having a substantial impact on population immunity in children and teenagers.     

Changes in seroprevalence to hepatitis A in Victoria, Australia: A comparison of three time points

Serological data provide an important measure of past exposure and immunity to hepatitis A virus (HAV) infection in a population. National serosurveys from developed countries have typically indicated a decline in HAV seroprevalence over time as sanitation levels improve. We examined trends in the seroepidemiology of HAV antibodies in Victoria, Australia, drawing on cross-sectional samples taken at three time points over a 20-year period. Stored sera from 1988 (n=753), 1998 (n=1091), and 2008 (n=791) from persons aged 1-69 years were obtained from the state of Victoria, Australia. The within-year population adjusted results show a significant trend of increasing population HAV seroprevalence over time from 34.3% (95% CI 31.7-36.9) in 1988, to 40.0% (95% CI 37.1-42.8) in 1998 and 55.1% (95% CI 52.1-58.1) in 2008, P<0.0001. A particularly noticeable rise in population seroprevalence was observed between 1998 and 2008 for those aged 5-39 years. The increase in HAV seropositivity over time is in contrast to the declining rates of disease notification in Australia. Based on comparisons with other Australian data, it appears the increase in population seroprevalence over the last two decades is unlikely to be due to endemic transmission of infection. Instead, other factors, including increases in travel to HAV endemic regions, migration to Australia from HAV endemic regions and vaccine uptake are more likely causes. Ongoing monitoring of serological HAV profiles in the population is required to determine future policy direction to prevent increased burden.     

Quantifying the impact of hepatitis A immunization in the United States, 1995-2001

Hepatitis A rates have declined to historically low rates in the United States. To assess the degree to which this decline was attributable to immunization, we correlated changes in the incidence of hepatitis A with increases in immunization coverage in a Poisson regression model. In a model allowing for herd immunity, an estimated 97,800 hepatitis A cases were averted due to immunization between 1995-2001, including 39% of potential cases in 2001. Assuming no herd immunity; 32,300 cases of hepatitis A would have been prevented. Sensitivity analysis showed that the number of averted cases in this period could range from 45,500 to 172,900. Among children 2-18 years old, vaccination coverage averaged 10% in 2001 and is estimated to have prevented 51% of cases in this age group. These results suggest that much of the recent reduction of hepatitis A rates is attributable to immunization and that immunization has been associated with a strong herd immunity effect.     

Seroprevalence of hepatitis B and factors potentially associated in a population-based study in Medellin,Colombia

The seroprevalence of hepatitis B (HB) and of potentially associated factors in Medellin, Colombia, were investigated 17 years after the start of universal vaccination. Biological and sociodemographic data from a population survey with a multistage random sampling were analyzed in 6–64 year old individuals. HB surface antigen, total HB core antibodies and HB surface antibodies, and in some cases IgM antibodies to HB core antigen, were tested in 2077 samples. Factors potentially associated with and natural, and vaccine immunity relative to susceptibility (absence of any marker) were analyzed using a multinomial logistic regression. The prevalence of serological patterns was: chronic infection 0.20% (95% CI 0.11–0.71), vaccine immunity 25.10% (95% CI 21.72–28.83) and natural immunity 2.60% (95% CI 1.80–3.74). No markers were detected in 71.30% (95% CI 67.70–74.83) of the individuals and evidence of recent infection was not detected. Relative to the absence of markers, natural immunity was potentially associated with age (6–17 years and 41–64 years) and sleeping less than 6 hours, while vaccine immunity was associated with age (6–17 years), reporting vaccination against HB, belonging to high socioeconomic strata, home ownership and being obese, after adjusting for other variables. These results may be a population effect of mass vaccination. It is recommended to complete the vaccination schedule and to study in detail, persistence of antibodies and the role of obesity and socioeconomic strata in the vaccine immunity.     

Outbreak of hepatitis A infection among intravenous drug users in Suffolk and suspected risk factors

A prolonged outbreak of hepatitis A infection amongst drug users in Suffolk prompted a study of the natural immunity against hepatitis A in this population, and a retrospective analysis of the relationship between specific drug-taking behaviours and the risk of hepatitis A infection. Prior to the outbreak, age-specific seroprevalence of hepatitis A IgG in drug users was similar to that amongst blood donors in the region. Of those without effective immunity, intravenous drug users, multiple drug users and those injecting frequently were more likely to have developed hepatitis. The reported frequency of equipment sharing and the number of injecting partners were not related to the risk of infection. The potential for blood-to-blood, and a suggested faecal-blood transmission were considered to be important in propagating the outbreak in this population. We suggest that a single dose of hepatitis A vaccine administered opportunistically should be used in outbreaks involving drug users.     

Impact of hepatitis A vaccination on health care utilization in the United States, 1996-2004

BACKGROUND: Since 1996, hepatitis A vaccine has been recommended for persons at risk for infection and children living in communities with the highest disease rates. In 1999, this recommendation was expanded to include all children in 17 states with high incidence compared to a national baseline period. Reported hepatitis A incidence has decreased substantially since 1999; however, comprehensive data on changes in hospital and outpatient utilization have not been reported. OBJECTIVE: To analyze a health insurance claims database to examine impacts of the hepatitis A vaccination program on medical visits and associated expenditures. METHODS: We conducted a retrospective study of the 1996-2004 Medstat MarketScan databases, which include enrollees of more than 100 health insurance plans offered by approximately 40 large employers each year, using 1996 and 1997 as the pre-vaccination baseline. Trends in rates of medical care visits were analyzed using Poisson regression method. RESULTS: From the pre-vaccination era to 2004, hospitalizations due to hepatitis A declined by 68.5% (from 0.81 to 0.26 per 100,000 population, P<0.001) and ambulatory visits declined by 41.5% (from 12.9 to 7.5 per 100,000 population, P<0.001). Ambulatory visits declined in all age groups, with the greatest declines among children<18 years old. Declines were greater among enrollees who resided in the 17 vaccinating states (58.5%) than those in non-vaccinating states (32.7%, P<0.001). After adjusting to the US population, using data derived from a privately insured population, total estimated direct medical expenditures for hepatitis A-related hospitalizations and ambulatory visits declined by 68.1%, from an average of $29.1 million in 1996 and 1997 to $9.3 million in 2004. CONCLUSIONS: Since the introduction of the hepatitis A vaccination program, hospitalizations, ambulatory visits, and their associated expenditures due to hepatitis A disease have declined substantially among all age groups across the US. Greater declines were seen in the 17 states with vaccination recommendations for hepatitis A.     

阜阳市甲型肝炎监测结果分析

目的了解阜阳市甲型肝炎的发病趋势和人群甲型肝炎疫苗免疫状况,为防治甲型肝炎提供科学依据。方法对甲型肝炎疫情资料及健康人群甲型肝炎免疫状况(甲肝疫苗接种率,抗-HAVIgG检测)进行调查及分析。结果自1990年以来,甲型肝炎的发病率基本上处于下降的趋势,无明显的发病高峰年。发病以0~14岁为多,其中5~9岁发病率最高(77.15/10万)。抽查人群甲肝疫苗接种率为28.37%(246/867),其中15岁以下儿童接种率为57.98%(189/326);761名健康人群抗-HAVIgG阳性率81.21%。在小于15岁的人群中有甲肝疫苗接种史的抗-HAVIgG的阳性率为94.52%(138/146),明显高于无免疫接种史的人群(55.37%,67/121)(2χ=56.88,P<0.01)。在无甲肝疫苗接种史的人群中,抗-HAVIgG阳性率随年龄而上升,20岁以上人群的阳性率几乎都在90%以上。结论加强15岁以下儿童甲型肝炎疫苗的免疫接种,是控制甲肝发生与流行的重要措施。     

Effectiveness of a hepatitis A vaccination program for migrant children in Amsterdam, The Netherlands (1992-2004)

OBJECTIVE: To evaluate the impact and effectiveness of risk-group vaccination against hepatitis A targeted at migrant children living in a country with low endemicity of hepatitis A. METHODS: Retrospective population based data analysis. Routinely collected data on hepatitis A incidence in migrant children and other risk groups in Amsterdam from 1 January 1992 to 2004 were analyzed and related to exposure, immunity and vaccination coverage in migrant children. RESULTS: The overall hepatitis A incidence in Amsterdam declined after a pediatric vaccine was introduced in 1997. This decline was seen in migrant children traveling to hepatitis A-endemic countries, contacts with hepatitis A patients, primary school students, injecting drug users, and persons with unknown source of infection, but not in men who have sex with men (MSM) or in travelers to endemic countries other than migrant children. CONCLUSION: The hepatitis A vaccination campaigns are effective: they reduce both import and secondary HAV cases. The campaigns could be more efficient and cost-effective if the hepatitis B vaccinations currently given to these groups were replaced by a combined hepatitis A and B vaccine. This would increase the hepatitis A vaccination coverage considerably and further reduce the hepatitis A incidence.     

广东省乙型肝炎血清流行病学调查研究

目的了解广东省人群乙型肝炎（乙肝）病毒（HBV）感染现状,评价乙肝疫苗免疫策略的效果。方法采取多阶段随机抽样方法,对全省6县区3 927名1-59岁人群进行乙肝血清流行病学研究,用ELISA方法检测乙肝表面抗原（HBsAg）、乙肝表面抗体（抗-HBs）和乙肝核心抗体（抗-HBc）,并调查1-14岁儿童乙肝疫苗接种情况。结果广东省1-59岁人群HBsAg阳性率、抗-HBs阳性率、抗-HBc阳性率和HBV感染率经标化后分别为15.46%、61.51%、49.46%和66.20%。1-14岁人群HBsAg阳性率和HBV感染率明显低于15-59岁人群。1-4岁人群HBsAg阳性率和HBV感染率低于5-14岁人群,而抗-HBs阳性率高于5-14岁人群。HBsAg阳性率和HBV感染率：男性高于女性,农村高于城市,城市人群抗-HBs阳性率高于农村。1-4岁儿童乙肝疫苗接种率为91.90%,全程接种率89.01%,首针及时接种率为58.38%,明显高于5-14岁人群。结论广东省仍是乙肝高流行区;乙肝疫苗纳入儿童免疫策略效果显著,1-14岁人群HBsAg携带率和HBV感染有不同程度下降,1-4岁下降尤为明显。     

Hepatitis B vaccination in a hyper-endemic tribal community from India: assessment after three years

Hepatitis B infection is highly endemic among the primitive tribes of Andaman and Nicobar Islands, India and it is necessary to initiate hepatitis B vaccination for control of this infection. A pilot project of mass hepatitis B vaccination using indigenously developed vaccine was initiated among Nicobarese tribe of Car Nicobar Island. Sero-protection rates after second and third year were 89% and 85.5%, respectively. The rate of chronic infection in the vaccinated population after three years was 1.86% compared to the pre-vaccination rate of 20.7%. Considering high sero-protection rates and low cost, the indigenous vaccine could be used for vaccination programme in this tribal community.     

北京市通州区20岁以上人群乙肝疫苗接种率影响因素分析

目的 了解北京市通州区20岁以上人群乙肝疫苗接种情况,分析乙肝疫苗接种率影响因素。方法 采用多阶段分层整群抽样方法,按地理位置距离中心城区远近抽取3个街道或乡镇的各1个居委会或自然村20岁以上成年人作为调查对象,对乙肝疫苗接种情况及影响因素开展问卷调查。结果 20岁以上人群乙肝疫苗接种率为7.2%(95%CI:5.3% ～ 9.1%)。文化程度是主要影响因素。父母、同学或同事是乙肝病人或携带者其暴露人群的乙肝疫苗接种率高于非暴露人群。其他乙肝病毒感染高危人群乙肝疫苗接种率较低。结论 通州区成人乙肝疫苗接种率低,应加强成人乙肝疫苗接种健康教育,科学开展成人疫苗接种的可及性和可行性的科学评估,减少乙肝病毒的传播风险。     

Hepatitis B school-based vaccination programmes in the USA: a model for hepatitis A and B

Following the recommendation for routine vaccination against hepatitis B virus for newborns, many states have started school-based catch-up vaccination of 11- to 12-year-olds. Implementation of these programmes requires educational and promotional initiatives to increase awareness among parents, children, teachers, school nurses, school boards and administration. Experience in Framingham, Massachusetts, suggests that over 90% of targeted hepatitis B vaccine coverage can be achieved. Because hepatitis B vaccination targeted at high-risk groups in the USA was largely unsuccessful, this suggests that the initial similar targeted approach with hepatitis A vaccination will also fail. Only about 50% of hepatitis A cases have a known risk factor, and multiple high-risk areas exist throughout the USA. However, the geographical clustering of these high-risk areas and the occurrence of periodic outbreaks, suggest that school-based hepatitis A vaccination programmes may be effective in reducing the risk of infection. A voluntary programme in San Antonio achieved 43% of the targeted coverage in its first year, and a compulsory programme is due to start in Oklahoma. The effectiveness of this programme is not yet known, but future recommendations are likely to include hepatitis A vaccination as a school entry requirement in areas with high incidence of hepatitis A.     

National serosurvey of poliovirus immunity in Australia, 1996-99

OBJECTIVE: To measure immunity to poliovirus types 1, 2 and 3 in the Australian population. METHODS: Sera were collected opportunistically from laboratories around Australia between 1996 and 1999. A representative sample by age and gender was tested for neutralising antibodies to poliovirus types 1, 2 and 3. A titre of > or = 8 was considered antibody positive and indicative of immunity. RESULTS: Of the 1,813 sera tested, 82% were antibody positive for poliovirus type 1 and 88% were positive for type 2. Immunity to type 3 poliovirus was lower overall (74%) and especially in school-aged children and young adults. For all three poliovirus types, there were more females immune than males and immunity peaked in the 2-4 years age group. The proportion of the population immune to all three types was 59%, and 3% were negative for all three types. CONCLUSIONS AND IMPLICATIONS: This is the first national serosurvey for immunity to poliovirus in Australia. Herd immunity is probably sufficient to prevent generalised outbreaks due to type 1 and 2 poliovirus, but this may not be the case for type 3. However, localised outbreaks of any poliovirus type could still occur following reintroduction unless uniformly high levels of vaccination coverage are maintained. Ongoing serosurveillance is required following the recent change back to inactivated polio vaccine.     

Reduction in the hepatitis B related burden of disease--measuring the success of universal immunisation programs.

There is collective evidence from countries of both low and high endemicity that administration of hepatitis B vaccination at birth saves lives and reduces the burden of disease from acute and chronic infection. However, a discussion on the cost-effectiveness of vaccination for HBV is beyond the scope of this article. In Australia, longer term follow-up of HBV disease burden is required following the more recent introduction of routine and universal infant vaccination. Universal vaccination for HBV at birth can be seen as a 'safety-net' against infection at a very young age. However, it is estimated that the effect of universal infant vaccination will not be evident for at least another 15 years in Australia. The obstacles to vaccination with HBV, which have historically included fears that the vaccine may be linked to multiple sclerosis, should be put to rest, and concerns about the thiomersal content allayed by communicating the current availability of thiomersal-free vaccines to all providers and parents or care-givers. Furthermore, ongoing adverse events surveillance should be in place to detect any rare adverse events which may be related to the vaccine. Currently, more than one half of the world's infants are still not being immunised for HBV, and the need for a global initiative for universal infant hepatitis B vaccination is apparent. This is especially true for countries with high prevalence, and the costing issues and logistics of such an initiative still remain to be addressed. In addition, there is a need to address the implementation of guidelines for screening and vaccination of families who have immigrated to Australia from countries with a high prevalence of hepatitis B.