Cost-effectiveness analysis of hepatitis A vaccination strategies for adults

Cost-effectiveness of hepatitis A vaccination in Indonesia

OBJECTIVE

This study aims to assess the cost-effectiveness of hepatitis A immunization in Indonesia, including an explicit comparison between one-dose and two-dose vaccines.

METHODS

An age-structured cohort model based on a decision tree was developed for the 2012 Indonesia birth cohort. Using the model, we made a comparison on the use of two-dose and one-dose vaccines. The model involved a 70-year time horizon with 1-month cycles for children less than 2 years old and annually thereafter. Monte Carlo simulations were used to examine the economic acceptability and affordability of the hepatitis A vaccination.

RESULTS

Vaccination would save US$ 3,795,148 and US$ 2,892,920 from the societal perspective, for the two-dose and one-dose vaccine schedules, respectively, in the context of hepatitis A treatment. It also would save 8917 and 6614 discounted quality-adjusted-life-years (QALYs), respectively. With the vaccine price of US$ 3.21 per dose, the implementation of single dose vaccine would yield an incremental cost-effectiveness ratio (ICER) of US$ 4933 per QALY gained versus no vaccination, whereas the two-dose versus one-dose schedule would cost US$ 14 568 per QALY gained. Considering the 2012 gross-domestic-product (GDP) per capita in Indonesia of US$ 3557, the results indicate that hepatitis A vaccination would be a cost-effective intervention, both for the two-dose and one-dose vaccine schedules in isolation, but two-dose vaccination would no longer be cost-effective if one-dose vaccination is a feasible option. Vaccination would be 100% affordable at budgets of US$ 71,408 000 and US$ 37,690,000 for the implementation of the two-dose and one-dose vaccine schedules, respectively.

CONCLUSIONS

The implementation of hepatitis A vaccination in Indonesia would be a cost-effective health intervention under the market vaccine price. Given the budget limitations, the use of a one-dose-vaccine schedule would be more realistic to be applied than a two-dose schedule. The vaccine price, mortality rate and discount rate were the most influential parameters impacting the ICERs.

Measuring underreporting and under-ascertainment in infectious disease datasets: a comparison of methods

BACKGROUND

Efficient and reliable surveillance and notification systems are vital for monitoring public health and disease outbreaks. However, most surveillance and notification systems are affected by a degree of underestimation (UE) and therefore uncertainty surrounds the 'true' incidence of disease affecting morbidity and mortality rates. Surveillance systems fail to capture cases at two distinct levels of the surveillance pyramid: from the community since not all cases seek healthcare (under-ascertainment), and at the healthcare-level, representing a failure to adequately report symptomatic cases that have sought medical advice (underreporting). There are several methods to estimate the extent of under-ascertainment and underreporting.

METHODS

Within the context of the ECDC-funded Burden of Communicable Diseases in Europe (BCoDE)-project, an extensive literature review was conducted to identify studies that estimate ascertainment or reporting rates for salmonellosis and campylobacteriosis in European Union Member States (MS) plus European Free Trade Area (EFTA) countries Iceland, Norway and Switzerland and four other OECD countries (USA, Canada, Australia and Japan). Multiplication factors (MFs), a measure of the magnitude of underestimation, were taken directly from the literature or derived (where the proportion of underestimated, under-ascertained, or underreported cases was known) and compared for the two pathogens.

RESULTS

MFs varied between and within diseases and countries, representing a need to carefully select the most appropriate MFs and methods for calculating them. The most appropriate MFs are often disease-, country-, age-, and sex-specific.

CONCLUSIONS

When routine data are used to make decisions on resource allocation or to estimate epidemiological parameters in populations, it becomes important to understand when, where and to what extent these data represent the true picture of disease, and in some instances (such as priority setting) it is necessary to adjust for underestimation. MFs can be used to adjust notification and surveillance data to provide more realistic estimates of incidence.

Hepatitis A and considerations regarding the cost-effectiveness of vaccination programs

Hepatitis A vaccines have demonstrated a high degree of immunogenicity and an excellent safety profile. Immunization of certain populations and patient subgroups is recommended according to specific epidemiological and clinical factors, such as a greater likelihood of acquisition of infection or concerns regarding the risk of development of fulminant hepatitis and death. Therefore, the economic implications of routine and/or targeted vaccination programs in the general population and high-risk individuals have been examined. In this manuscript, the available data from the literature regarding the cost-effectiveness of hepatitis vaccination programs in healthy individuals and in those with chronic liver disease are reviewed.

The use of modeling in the economic evaluation of vaccines

As a consequence of the increased role of pharmacoeconomics in policy-making, economic evaluations are performed at more and more early stages in the development of a therapeutic. This implies the development of models to assess the future impact of an intervention and to account for the level of uncertainty in the associated parameters. This also applies for economic evaluations of vaccines, where not only progression of disease and associated costs are important, but the transmission of the causing agent in the target population also has to be modelled. In this review, we provide an overview of the models that have been used in recent publications on the pharmacoeconomics of vaccines and go deeper into some of the methodological issues associated with the use of models in the economic evaluation of vaccines.

Cost-effectiveness of hepatitis A vaccination for individuals with chronic hepatitis C

The incidence of hepatitis A infection in the United States has decreased dramatically in recent years because of childhood immunization programs. A decision analysis of the cost-effectiveness of hepatitis A vaccination for adults with hepatitis C was conducted. No vaccination strategy is cost-effective for adults with hepatitis C using the recent lower anticipated hepatitis A incidence, private sector costs, and a cost-effectiveness criterion of $100,000/QALY. Vaccination is cost-effective only for individuals who have cleared the hepatitis C virus when Department of Veterans Affairs costs are used. The recommendation to vaccinate adults with hepatitis C against hepatitis A should be reconsidered.

Costing infectious disease outbreaks for economic evaluation: a review for hepatitis A

With the aim to understand and estimate the economic impact of outbreaks of community-acquired infections, we performed a review focusing on hepatitis A outbreaks, and retained 13 papers that had collected relevant cost information during such outbreaks. All costs in this article are expressed in USD, year 2007 values. The costs of hepatitis A outbreaks ranged from USD140 000 to US36 million, and the costs per case in an outbreak situation ranged from USD3824 to USD200 480. These costs were typically found to be substantially higher than estimates from cost-of-illness studies (i.e. costs for sporadic cases) and estimates used in cost-effectiveness analyses, mostly because of costly outbreak-control measures. Post-exposure prophylaxis is a major cost factor, especially for food-borne outbreaks. As a result of the increasing proportion of those susceptible to hepatitis A in low-incidence countries, future outbreaks could, on average, increase in size. The increasing occurrence of hepatitis A cases in outbreak situations and the associated control costs should appropriately be accounted for in economic evaluations of vaccination programmes in low-incidence countries. In order to do this, more studies documenting such outbreak-control strategies in terms of costs and resource use are needed.

Cost-effectiveness analysis of behavioral interventions to improve vaccination compliance in homeless adults

AIMS

To estimate the cost-effectiveness of three behavioral interventions provided to enhance hepatitis A virus (HAV) and hepatitis B virus (HBV) joint vaccination (HAV/HBV) compliance among homeless persons living in Los Angeles County.

SCOPE

A cost-effectiveness analysis (CEA) based on data from a randomized trial where the costs and compliance data from the trial are incorporated into two Markov models, simulating the natural history of acute and chronic hepatitis infection, following HAV/HBV vaccination.

CONCLUSIONS

Reductions in HBV-related disease is cost-effective to society and is associated with substantial improvements in quality of life.

Cost-effectiveness analyses of hepatitis A vaccine: a systematic review to explore the effect of methodological quality on the economic attractiveness of vaccination strategies

Hepatitis A vaccines have been available for more than a decade. Because the burden of hepatitis A virus has fallen in developed countries, the appropriate role of vaccination programmes, especially universal vaccination strategies, remains unclear. Cost-effectiveness analysis is a useful method of relating the costs of vaccination to its benefits, and may inform policy. This article systematically reviews the evidence on the cost effectiveness of hepatitis A vaccination in varying populations, and explores the effects of methodological quality and key modelling issues on the cost-effectiveness ratios.Cost-effectiveness/cost-utility studies of hepatitis A vaccine were identified via a series of literature searches (MEDLINE, EMBASE, HSTAR and SSCI). Citations and full-text articles were reviewed independently by two reviewers. Reference searching, author searches and expert consultation ensured literature saturation. Incremental cost-effectiveness ratios (ICERs) were abstracted for base-case analyses, converted to $US, year 2005 values, and categorised to reflect various levels of cost effectiveness. Quality of reporting, methodological issues and key modelling issues were assessed using frameworks published in the literature.Thirty-one cost-effectiveness studies (including 12 cost-utility analyses) were included from full-text article review (n = 58) and citation screening (n = 570). These studies evaluated universal mass vaccination (n = 14), targeted vaccination (n = 17) and vaccination of susceptibles (i.e. individuals initially screened for antibody and, if susceptible, vaccinated) [n = 13]. For universal vaccination, 50% of the ICERs were <$US20 000 per QALY or life-year gained. Analyses evaluating vaccination in children, particularly in high incidence areas, produced the most attractive ICERs. For targeted vaccination, cost effectiveness was highly dependent on the risk of infection.Incidence, vaccine cost and discount rate were the most influential parameters in sensitivity analyses. Overall, analyses that evaluated the combined hepatitis A/hepatitis B vaccine, adjusted incidence for under-reporting, included societal costs and that came from studies of higher methodological quality tended to have more attractive cost-effectiveness ratios. Methodological quality varied across studies. Major methodological flaws included inappropriate model type, comparator, incidence estimate and inclusion/exclusion of costs.

Cost-effectiveness of routine childhood vaccination for hepatitis A in the United States

OBJECTIVES

Economic analysis is an important component in formulating national policy. We evaluated the economic impact of hepatitis A vaccination of all US children ages 12 to 23 months as compared with no vaccination and with current implementation of the preexisting (issued in 1999), regional policy.

METHODS

We developed a Markov model of hepatitis A that followed a single cohort from birth in 2005 through death or age 95 years. From the societal perspective, the model compared the outcomes that resulted from routine vaccination at age 1 year to 2 scenarios: no hepatitis A vaccination and hepatitis A vaccination at levels observed in 2003 under the preexisting policy. We evaluated the economic impact of vaccination nationwide, in areas where vaccination was already recommended, and in areas where no previous recommendation existed.

RESULTS

Without childhood vaccination, the approximately 4 million children in the 2005 birth cohort would be expected over their lifetimes to have 199,000 hepatitis A virus infections, including 74,000 cases of acute hepatitis A and 82 deaths, resulting in 134 million dollars in hepatitis A-related medical costs and productivity losses. Compared with no vaccination, routine vaccination at age 1 year would prevent 172,000 infections, at a cost of 28,000 dollars per quality-adjusted life year saved. Compared with maintaining the levels of hepatitis A vaccination under the preexisting regional policy, routine vaccination at age 1 year would prevent an additional 112,000 infections, at a cost of 45,000 dollars per quality-adjusted life year saved.

CONCLUSIONS

The cost-effectiveness of nationwide hepatitis A vaccination compared with no vaccination, and the incremental cost-effectiveness of this recommendation compared with preexisting recommendations, is similar to that of other accepted public health interventions. In October 2005, the Advisory Committee on Immunization Practices recommended extending hepatitis A immunization to all US children ages 12 to 23 months.

Health risks of enteric viral infections in children

Children are at a greater risk of infections from serious enteric viral illness than adults for a number of reasons. Most important is the immune system, which is needed to control the infection processes. This difference can lead to more serious infections than in adults, who have fully developed immune systems. There are a number of significant physiological and behavioral differences between adults and children that place children at a greater risk of exposure and a greater risk of serious infection from enteric viruses. Although most enteric viruses cause mild or asymptomatic infections, they can cause a wide range of serious and life-threatening illnesses in children. The peak incidence of most enteric viral illnesses is in children <2yr of age, although all age groups of children are affected. Most of these infections are more serious and result in higher mortality in children than adults. The fetus is also affected by enterovirus and infectious hepatitis resulting in significant risk of fetal death or serious illness. In addition to the poliovirus vaccine, the only vaccine available is for hepatitis A virus (HAV). A vaccine for rotavirus has currently been withdrawn, pending review because of potential adverse effects in infants. No specific treatment is available for the other enteric viruses. Enteric viral infections are very common in childhood. Most children are infected with rotavirus during the first 2yr of life. The incidence of enteroviruses and the viral enteric viruses ranges from 10% to 40% in children and is largely dependent on age. On average, half or more of the infections are asymptomatic. The incidence of hepatitis A virus is much lower than the enteric diarrheal viruses. There is no current evidence for hepatitis E virus (HEV) acquisition in children in the U.S. Enteric viral diseases have a major impact on direct and indirect health care costs (i.e., lost wages) and amount to several billion dollars a year in the U.S. Total direct and indirect costs for nonhospitalized cases may run from $88/case for Norwalk virus to $1,193/case for enterovirus aseptic meningitis. Direct costs of hospitalization ran from $887/case for Norwalk virus to $86,899/case for hepatitis A. These costs are based on 1997-1999 data. Generally, attack rates during drinking water outbreaks are greater for children than adults. The exception appears to be hepatitis E virus where young adults are more affected. However, pregnant women suffer a high mortality, resulting in concurrent fetal death. Also, secondary attack rates are much higher among children, probably because of fewer sanitary habits among this age group. Overall, waterborne outbreaks of viral disease have a greater impact among children than adults. To better quantify the impact on children, the literature hould be further reviewed for case studies of waterborne outbreaks where data are available on the resulting illness by age group. The EPA and/or Centers for Disease Control should attempt to collect these data as future outbreaks are documented.

Cost-effectiveness of hepatitis A-B vaccine versus hepatitis B vaccine for healthcare and public safety workers in the western United States

OBJECTIVE

To determine the cost-effectiveness of substituting hepatitis A-B vaccine for hepatitis B vaccine when healthcare and public safety workers in the western United States are immunized to protect against occupational exposures to hepatitis B.

PARTICIPANTS

A cohort of 100,000 hypothetical healthcare and public safety workers from 11 western states with hepatitis A rates twice the national average.

DESIGN

A Markov model of hepatitis A was developed using estimates from U.S. government databases, published literature, and an expert panel. Added costs of hepatitis A-B vaccine were compared with savings from reduced hepatitis A treatment and work loss. Cost-effectiveness was expressed as the ratio of net costs to quality-adjusted life-years (QALYs) gained.

RESULTS

Substituting hepatitis A-B vaccine would prevent 29,796 work-loss-days, 222 hospitalizations, 6 premature deaths, and the loss of 214 QALYs. Added vaccination costs of $5.4 million would be more than offset by $1.9 million and $6.1 million reductions in hepatitis A treatment and work loss costs, respectively. Cost-effectiveness improves as the time horizon is extended, from $232,600 per QALY after 1 year to less than $0 per QALY within 11 years. Estimates are most sensitive to community-wide hepatitis A rates and the degree to which childhood vaccination may reduce future rates.

CONCLUSION

For healthcare and public safety workers in western states, substituting hepatitis A-B vaccine for hepatitis B vaccine would reduce morbidity, mortality, and costs.

Cost effectiveness of hepatitis A/B versus hepatitis B vaccination for US prison inmates

Hepatitis B immunization is provided in many US prison systems. We examined the cost effectiveness of substituting bivalent hepatitis A/B vaccine in this setting, considering regional variation in hepatitis A risks and the potential for disease transmission by former prisoners. Where hepatitis A rates are >200, 100-200, and <100% the national average, declines in hepatitis A treatment costs would offset 137, 88, and 40% of the bivalent vaccine's added cost. In the three regions considered, cost effectiveness would be US$ <0, 2131, and 22,819 per life-year saved, respectively. Prison-based hepatitis A/B immunization would meet accepted standards of cost effectiveness throughout the US.

An economic assessment of pre-vaccination screening for hepatitis A and B

OBJECTIVE

The availability of a single vaccine active against hepatitis A and B may facilitate prevention of both infections, but complicates the question of whether to conduct pre-vaccination screening. The authors examined the cost-effectiveness of pre-vaccination screening for several populations: first-year college students, military recruits, travelers to hepatitis A-endemic areas, patients at sexually transmitted disease clinics, and prison inmates.

METHODS

Three prevention protocols were examined: (1) screen and defer vaccination until serology results are known; (2) screen and begin vaccination immediately to avoid a missed vaccination opportunity; and (3) vaccinate without screening. Data describing pre-vaccination immunity, vaccine effectiveness, and prevention costs borne by the health system (i.e., serology, vaccine acquisition, and administration) were derived from published literature and U.S. government websites. Using spreadsheet models, the authors calculated the ratio of prevention costs to the number of vaccine protections conferred.

RESULTS

The vaccinate without screening protocol was most cost-effective in nine of 10 analyses conducted under baseline assumptions, and in 69 of 80 sensitivity analyses. In each population considered, vaccinate without screening was less costly than and at least equally as effective as screen and begin vaccination. The screen and defer vaccination protocol would reduce costs in seven populations, but effectiveness would also be lower.

CONCLUSIONS

Unless directed at vaccination candidates with the highest probability of immunity, pre-vaccination screening for hepatitis A and B immunity is not cost-effective. Balancing cost reduction with reduced effectiveness, screen and defer may be preferred for older travelers and prison inmates.

An economic assessment of pre-vaccination screening for hepatitis A and B

OBJECTIVE

The availability of a single vaccine active against hepatitis A and B may facilitate prevention of both infections, but complicates the question of whether to conduct pre-vaccination screening. The authors examined the cost-effectiveness of pre-vaccination screening for several populations: first-year college students, military recruits, travelers to hepatitis A-endemic areas, patients at sexually transmitted disease clinics, and prison inmates.

METHODS

Three prevention protocols were examined: (1) screen and defer vaccination until serology results are known; (2) screen and begin vaccination immediately to avoid a missed vaccination opportunity; and (3) vaccinate without screening. Data describing pre-vaccination immunity, vaccine effectiveness, and prevention costs borne by the health system (i.e., serology, vaccine acquisition, and administration) were derived from published literature and U.S. government websites. Using spreadsheet models, the authors calculated the ratio of prevention costs to the number of vaccine protections conferred.

RESULTS

The vaccinate without screening protocol was most cost-effective in nine of 10 analyses conducted under baseline assumptions, and in 69 of 80 sensitivity analyses. In each population considered, vaccinate without screening was less costly than and at least equally as effective as screen and begin vaccination. The screen and defer vaccination protocol would reduce costs in seven populations, but effectiveness would also be lower.

CONCLUSIONS

Unless directed at vaccination candidates with the highest probability of immunity, pre-vaccination screening for hepatitis A and B immunity is not cost-effective. Balancing cost reduction with reduced effectiveness, screen and defer may be preferred for older travelers and prison inmates.

Cost-Effectiveness of Hepatitis A/B Vaccine versus Hepatitis B Vaccine in Public Sexually Transmitted Disease Clinics

BACKGROUND

Many patients seen at U.S. sexually transmitted disease (STD) clinics are offered hepatitis B vaccination. Substituting hepatitis A/B vaccine would provide additional protection but increase costs.

GOAL

The goal was to estimate the cost effectiveness of hepatitis A/B versus B vaccination for 1,000,000 public STD clinic attenders.

STUDY DESIGN

A Markov model of hepatitis A outcomes was developed using published literature, U.S. government databases, and expert panel opinion. Added vaccination costs were compared with savings from reduced hepatitis A treatment. Net costs were compared with life-years saved and quality-adjusted life-years (QALYs) gained.

RESULTS

Substituting hepatitis A/B vaccine would prevent 2263 overt hepatitis A infections, 292 hospitalizations, 8 premature deaths, and the loss of 281 QALYs. Net health system costs would be $20,892 per life-year saved, or $13,397 per QALY gained.

CONCLUSION

Substituting hepatitis A/B for hepatitis B vaccine would reduce morbidity and mortality in a cost-effective manner.

Economic impact of a hepatitis A epidemic in a mid-sized urban community: the case of Spokane, Washington

Data reported here represent an effort to build on previous work regarding the costs of hepatitis A. We expand this work to include an estimation of the costs of hepatitis A on a community wide basis. In addition to calculating the costs of disease management and health care delivery, we include an analysis of additional child care costs, lost productivity, costs associated with outbreak management, and the impact on affected restaurants that required public notification and the administration of Immune Globulin to patrons. The work reported here is specific to Spokane county, Washington. The objective is to enable the Spokane Regional Health District to communicate to the community costs of managing an outbreak of hepatitis A and to inform implementation of a hepatitis A vaccination program on a community wide basis. The average cost (direct and indirect) per case for the entire sample is 2,683 dollars. The estimated total cost for the sample (145 cases) is approximately 370,193 dollars. Inpatient hospital care is the largest direct medical expense and lost productivity is a major indirect cost to the community. Lessons learned from undertaking this task include: (1) costs incurred are not immediately obvious, (2) without infrastructure in place, tracking costs is difficult, if not impossible, (3) potential for large expenditures is apparent, (4) estimates are consistent with those generated in previous studies, and (5) previous findings of vaccination of certain high-risk populations as a cost-efficient approach is corroborated.

Cost-effectiveness of a pneumococcal conjugate immunisation program for infants in Switzerland

OBJECTIVE

To compare projected economic costs and health benefits associated with using pneumococcal conjugate heptavalent vaccine as routine immunisation in healthy children in Switzerland.

DESIGN

A cost-utility analysis was performed from both the societal as well as the sickness funds' perspective.

SETTING

Simulated birth cohorts of 80,000 children (the approximate size of a birth cohort in Switzerland) were followed from birth up to age of 5.

MAIN OUTCOME MEASURES

Reduction in disease burden, costs of vaccination, cost-utility ratio (cost per quality-adjusted life year (QALY)).

RESULTS

With a vaccine coverage of 70% vaccination of newborns only would avert 4 deaths, 8 cases of meningitis, 37 cases of other invasive pneumococcal disease, 150 cases of pneumococcal pneumonia and about 2700 cases of otitis media (OM) per year. The net cost of the vaccination program would be 22 Mio. CHF per year for society and about 19 Mio. CHF for the sickness funds. This results in a cost-utility ratio of 35,700 CHF (approximately 26,300 USD (1)) per QALY from the societal perspective and 39,300 CHF (28,900 USD) per QALY from the sickness funds' perspective. Additional catch-up vaccination of all infants <24 months in the years after vaccine introduction would result in additional benefits at a cost of 33,600 CHF per additional QALY gained. However, if the catch-up vaccination should include all children <60 months, each additional QALY would be gained at a very high cost (162,000 CHF per additional QALY).

CONCLUSIONS

Routine vaccination of healthy infants <2 years in Switzerland can reduce mortality and long term neurologic impairment resulting from invasive pneumococcal disease at a reasonable cost-utility ratio.

The cost effectiveness of hepatitis immunization for US college students

Hepatitis B immunization is recommended for all American children, and hepatitis A immunization is recommended for children who live in areas with elevated disease rates. Because hepatitis A and B occur most commonly in young adults, the authors examined the cost effectiveness of college-based vaccination. They developed epidemiologic models to consider infection risks and disease progression and then compared the cost of vaccination with economic, longevity, and quality of life benefits. Immunization of 100,000 students would prevent 1,403 acute cases of hepatitis A, 929 cases of hepatitis B, and 144 cases of chronic hepatitis B. Hepatitis B vaccination would cost the health system $7,600 per quality-adjusted life year (QALY) gained but would reduce societal costs by 6%. Hepatitis A/B vaccination would cost the health system dollar 8,500 per QALY but would reduce societal costs by 12%. Until childhood and adolescent vaccination can produce immune cohorts of young adults, college-based hepatitis immunization can reduce disease transmission in a cost-effective manner.

Cost-effectiveness of hepatitis A vaccination in children, adolescents, and adults

Hepatitis A is a major public health problem in the United States and other developed countries, largely because decreased natural immunity allows for increased susceptibility. To evaluate the cost-effectiveness of routine vaccination of children, adolescents, and certain high-risk adults against hepatitis A, economic analyses of hepatitis A vaccination were identified through searches of MEDLINE, EMBASE, and BIOSIS (February, 1992, to December, 2001) for studies, reviews, editorials, and letters from peer-reviewed journals published in English, French, German, Italian, or Spanish. Experts were also contacted. Articles conforming to accepted standards of quality for health-economic studies were used to compile data on vaccination of children, and results were synthesized in a narrative review. This review of economic analyses of vaccine use in several developed countries shows cost-effectiveness comparable with that of other vaccines in children and within accepted boundaries for adolescents and high-risk adults.

Immunizations for international travel

Many infections encountered by international travelers can be prevented by adherence to personal protective measures and appropriate vaccinations. This review outlined the incidence and importance of the major vaccine-preventable infectious diseases encountered by U.S. travelers, as well as the indications, contraindications, and side effects of available vaccines. Official proof of yellow fever vaccine often is required for entry into some countries. Based on endemic or epidemic infections at destinations, planned activities, and age and medical history of international travelers, other vaccines may be recommended. Many clinicians will be familiar with some of the infections and vaccines that may be used in travelers; other vaccines may be encountered infrequently and associated with significant risk of adverse effects. Since vaccines do not provide complete protection and some travel-related infections do not have vaccines available yet (e.g., malaria and dengue fever), physicians need to be vigilant concerning febrile illness in returning travelers.

Prevention of Viral Hepatitis

Despite the availability of vaccines against hepatitis A and B, acute viral hepatitis due to these agents continues to be among the most commonly reported notifiable infectious diseases in the United States. Currently available hepatitis A and B vaccines are highly immunogenic and well tolerated, but vaccine coverage needs to be expanded. Use of the hepatitis A vaccine in children age 2 years and older should be more widespread than is currently the case. Hepatitis A vaccine has been shown to be cost effective when given to children in regions with high attack rates and to patients with chronic hepatitis C. Routine newborn immunization against hepatitis B has been a successful approach to disease control and is among the most cost-effective interventions. Use of the hepatitis B vaccine for all sexually active individuals with more than one sex partner should be recommended for this sexually transmitted disease. The availability of a combined hepatitis A and B vaccine should facilitate vaccine coverage in those individuals at risk for both infections. For those hepatitis infections for which no vaccine is currently available, namely hepatitis C, D, and E, reducing exposure risk by modifying lifestyle behaviors is the only control measure available. Early education and counseling about high-risk behaviors for the acquisition of blood-borne hepatitis viruses needs to be expanded to young children and adolescents. The eventual eradication of hepatitis virus infections through universal immunization is plausible for those agents for whom human beings are the only host and effective vaccines have been developed. If hepatitis E is shown to be a zoonosis with an extensive reservoir in pigs, eradication of this agent may be very difficult.

Prescreening versus empirical immunization for hepatitis A in patients with chronic liver disease: a prospective cost analysis

OBJECTIVES

There are few prospective studies estimating the prevalence of hepatitis A in chronic liver disease patients. Furthermore, there are minimal cost-comparative data as to whether or not screening for hepatitis A exposure before immunization is an effective fiscal strategy. The objectives of this study were to determine the prevalence of prior hepatitis A infection and to perform a prospective cost analysis for hepatitis A immunization in patients with chronic liver disease.

METHODS

This is a prospective cohort study of 100 patients with chronic liver diseases. Patients were screened for potential risk factors for hepatitis A including history of jaundice, socioeconomic status, birth origin, and ethnic background. Each patient underwent testing for evidence of prior infection using an ELISA. Seronegative patients then went on to receive an immunization series. Cost analysis of vaccination without prescreening (universal strategy) was compared to cost analysis of prescreening and selective immunization of those without prior infection (selective strategy).

RESULTS

Fifty-three patients (53%) had serological evidence of prior hepatitis A infection (95% CI = 43-63%). Of the risk factors assessed, foreign birth was associated with prior hepatitis A exposure (p = 0.0002). Cost analysis revealed that prescreening for hepatitis A before vaccination was cost saving given the current prevalence.

CONCLUSIONS

The seroprevalence of hepatitis A in those with chronic liver diseases was 53%. Cost analysis revealed that screening for hepatitis A before immunization is cost saving, and this strategy should be applied to follow current vaccination guidelines.

Inactivated hepatitis A vaccine: immunogenicity, efficacy, safety and review of official recommendations for use

There is 10 years of marketing experience with the hepatitis A vaccine Havrix. It is highly immunogenic, provides lasting protection in healthy individuals and generates protective levels of antibodies in patients with chronic liver disease or impaired immunity. Postmarketing surveillance data have confirmed the outstanding safety profile of the vaccine. The timing of the booster dose is not critical to effectiveness, which has advantages for the protection of travelers to regions of high endemicity. The vaccine is effective in curbing outbreaks of hepatitis A and also when administered postexposure, due to rapid seroconversion and the long incubation period of the disease. In intermediate endemic regions, an epidemiological shift in hepatitis A infection has driven the development of universal preventive strategies to be added to the targeting of at-risk groups. Existing official recommendations and future directions for vaccine use are reviewed.

Empiric immunization versus serologic screening: developing a cost-effective strategy for the use of hepatitis A immunization in travelers

BACKGROUND

Older individuals and those born overseas are thought at increased risk of prior exposure and thus have naturally acquired immunity to hepatitis A. Whether these individuals or other groups of international travelers should be screened for acquired immunity or empirically immunized is not clear. Hepatitis A serology and risk factor data was obtained prospectively in patients presenting for hepatitis A immunization and used to develop a cost-effective strategy for the use of serologic screening and empiric immunization in our traveler population.

METHOD

Candidates for hepatitis A immunization were routinely screened for total hepatitis A serum antibody. Risk factor data including country of birth, travel history, and history of jaundice was collected. Cost-effectiveness was assessed by comparing the cost of serology to screen all patients plus cost to immunize those found to be seronegative with, the cost of empirically immunizing all patients.

RESULTS

Analyses were conducted comparing age, travel history, country of birth, and history of jaundice for significance in predicting seropositivity in a group of 115 subjects. Country of birth was statistically a significant predictor of positive results with 80.0% of foreign-born patients positive for total antibody against hepatitis A compared with 35.6% of patients born in the United States. Living outside of the United States (defined as greater than 30 days) was also correlated with a higher prevalence of hepatitis A positive serology. Age was not predictive for the group as a whole. A lower prevalence (24.3%) was noted in the group of US born individuals aged 30 to 60. Travel and prior history of jaundice failed to demonstrate significance.

CONCLUSIONS

Employing a simple cost-effectiveness equation using cost of serological testing, cost of vaccine, and prevalence of acquired immunity in the community, a strategy was developed. In our population it was cost-effective to screen all foreign-born individuals and those who had lived outside the United States.

Epidemiology and prophylaxis of viral hepatitis: a global perspective

BACKGROUND

Viral hepatitis with various forms of acute and chronic liver disease as potential and ultimately fatal sequelae presents a public health problem worldwide.

METHODS

Recent published reports on the global epidemiology and prophylaxis of viral hepatitis were reviewed.

RESULTS

With the advances in novel technologies, eight distinct types of hepatitis virus have been described: Hepatitis A, B, C, D, E, G, TT and SEN viruses. Hepatitis A and E viruses are transmitted by the fecal-oral route and do not induce a chronic carrier state. Due to major changes in epidemiology of hepatitis A virus their significance is more pronounced in areas of intermediate endemicity. Since the available hepatitis A vaccine is rather expensive, cost-benefit studies should be performed with emphasis on the area under consideration or specialized vulnerable groups. Parenterally transmitted hepatitis B and C viruses are major causes of chronic liver disease, including cirrhosis, hepatocellular carcinoma and end-stage liver failure. Hepatitis D virus is unable to replicate on its own, it requires an established hepatitis B virus infection to be able to replicate. Since its introduction, hepatitis B vaccine has been widely used leading to a significant decrease in HBV infection in countries with universal vaccination. Hepatitis G and TT viruses have been characterized within the latter part of the past decade but their significance as to the causation of human liver disease has yet to be elucidated. Likewise, the precise impact of the most recently described SEN virus isolated from patients with post-transfusion hepatitis awaits further studies.

CONCLUSIONS

In the course of this review, we present the situation and focus on research activities emphasizing epidemiology and prevention of the various forms of viral hepatitis.

The cost-effectiveness of vaccinating chronic hepatitis C patients against hepatitis A

OBJECTIVES

Although hepatitis A vaccination is recommended for persons with chronic liver disease, the cost-effectiveness of vaccinating patients with chronic hepatitis C virus has not been extensively studied. We evaluated its costs and benefits.

METHODS

A Markov model was used to assess cost-effectiveness from the health system and societal perspectives. Costs of hepatitis A screening and vaccination were compared with savings from reduced hepatitis A treatment and work loss to determine net costs of a "screen and vaccinate" strategy. Net costs were compared with longevity gains to assess cost-effectiveness.

RESULTS

Based on hypothetical cohorts of 100,000 patients, vaccination would reduce the number of hepatitis A cases 63-72%, depending on patient age. Screening and vaccination costs of $5.2 million would be partially offset by $1.5-$2.8 million reductions in hepatitis A treatment costs and $0.2-$1.0 million reductions in work loss costs. From the health system perspective, vaccination would cost $22,256, $50,391, and $102,064 per life-year saved for patients vaccinated at ages 30, 45, and 60 yr, respectively. Cost-effectiveness ratios improve when work loss prevention is considered. Results are most sensitive to hepatitis A infection and hospitalization rates, and the rate used to discount future benefits to their present values.

CONCLUSIONS

Hepatitis A vaccination of chronic hepatitis C patients would substantially reduce morbidity and mortality in all age groups examined. Consistent with other medical interventions for chronic hepatitis C patients, cost-effectiveness is most favorable for younger patients.

Valuation of symptomatic hepatitis a in adults: estimates based on time trade-off and willingness-to-pay measurement

BACKGROUND

The cost effectiveness of hepatitis A prevention is typically assessed by comparing vaccination costs with the number of life-years saved. This endpoint does not consider the benefits of preventing nonfatal yet symptomatic infections. Nearly as many days of healthy life are lost to hepatitis A morbidity as mortality.

OBJECTIVE

To investigate the value American adults place on preventing hepatitis A symptoms by using the willingness-to-pay and time trade-off metrics.

METHODS

We provided a written description of hepatitis A symptoms to 181 American adults, who judged the amounts of money and lifespan they would forego to avoid them. The description made no reference to the possibility of fatality, and respondents were asked not to consider costs of medical care and work loss. We investigated relationships between demographic characteristics and each metric, the relationship between the two metrics, and the test/re-test reliability of the metrics.

RESULTS

Respondents would pay a median of dollars US 2000 (inter-quartile range, dollars US 500 to 5000; 2001 values) for risk-free prevention of hepatitis A symptoms. Alternatively, they would forego a median of 28 days survival (inter-quartile range, 6 to 40 days) for cost-free prevention. There was modest correlation between willingness-to-pay and time trade-off responses (r = 0.24, p < 0.01), suggesting these metrics measure independent aspects of preference. Strong correlations between measures obtained 30 days apart support the test/re-test reliability of willingness to pay (r = 0.70, p < 0.01) and time trade-off (r = 0.73, p < 0.01) metrics. In multivariate analyses, higher household income (p = 0.02) predicted greater willingness to pay in dollars. Male gender (p < 0.01) predicted greater willingness to forego life expectancy for better health.

CONCLUSION

In our study population of US adults, most were willing to pay or trade life expectancy for a hypothetical preventative drug for hepatitis A symptoms. The amount respondents were willing to pay appears dependent on their income level while males are willing to trade more life expectancy than female respondents. The values expressed should be considered in assessments of hepatitis A prevention.

Cost analysis of two strategies for hepatitis A vaccination of hospital health-care personnel in an intermediate endemicity area

The aim of the study was to carry out a cost analysis to allow the comparison of the cost of two vaccination strategies against Hepatitis A in health-care personnel. A total of 423 health-care workers were recruited at one General Hospital of Madrid, Spain. Blood specimens were obtained for anti-HAV antibody determination. The prevalence of anti-HAV antibody was 40% (95% CI: 35-45) and it was directly correlated with age. Cost analysis determined that the critical value of prevalence for vaccination with HAV vaccine was 23%. In hospital health-care workers < or =30 years in age, vaccination with HAV vaccine (without screening) would be the less costly strategy. In those >30 years in age, it would be less costly to screen for anti-HAV antibody first and vaccinate those who are antibody-negative.

Hepatitis A: old and new

The hepatitis A virus (HAV), a picornavirus, is a common cause of hepatitis worldwide. Spread of infection is generally person to person or by oral intake after fecal contamination of skin or mucous membranes; less commonly, there is fecal contamination of food or water. Hepatitis A is endemic in developing countries, and most residents are exposed in childhood. In contrast, the adult population in developed countries demonstrates falling rates of exposure with improvements in hygiene and sanitation. The export of food that cannot be sterilized, from countries of high endemicity to areas with low rates of infection, is a potentially important source of infection. After ingestion and uptake from the gastrointestinal tract, the virus replicates in the liver and is excreted into the bile. Cellular immune responses to the virus lead to destruction of infected hepatocytes with consequent development of symptoms and signs of disease. Humoral immune responses are the basis for diagnostic serologic assays. Acute HAV infection is clinically indistinguishable from other causes of acute viral hepatitis. In young children the disease is often asymptomatic, whereas in older children and adults there may be a range of clinical manifestations from mild, anicteric infection to fulminant hepatic failure. Clinical variants include prolonged, relapsing, and cholestatic forms. Management of the acute illness is supportive, and complete recovery without sequelae is the usual outcome. Research efforts during World War II led to the development of passive immunoprophylaxis. Pooled immune serum globulin is efficacious in the prevention and attenuation of disease in exposed individuals. More recently, active immunoprophylaxis by vaccination has been accomplished. Future eradication of this disease can now be contemplated.

Hepatitis A

Hepatitis A remains an important cause of community-acquired hepatitis in the United States and in the world. In recent years, improvements in personal hygiene and environmental sanitation have led to declines in overall hepatitis A infection rates in developed countries, although sporadic outbreaks still occur with similar rates of hospitalization and loss of work. Therapy remains supportive and prevention holds the key to elimination of widespread infection. Acute infection can be prevented or attenuated with IG or with inactivated, highly immunogenic vaccines. Elderly persons and those with advanced liver disease are at higher risk of the consequences of acute HAV, and they represent target populations for immediate vaccination. Challenges for the future include strategies for broad-based population vaccination, including cost-effective approaches.

The cost-effectiveness of hepatitis A vaccination in patients with chronic hepatitis C

Infection with hepatitis A virus (HAV) occasionally leads to acute liver failure and has a higher fatality rate in patients with chronic hepatitis C virus (HCV). Vaccination of patients with HCV against HAV is effective and well tolerated. This study examines the cost-effectiveness of HAV vaccination in North American patients with chronic HCV. A decision analysis model was constructed to compare 3 HAV vaccination strategies in adult patients with chronic HCV over a period of 5 years: (1) vaccinate no patients (treat none); (2) vaccinate only susceptible (anti-HAV negative) patients (selective); or (3) vaccinate all patients without prior testing of immune status (universal). Probabilities and direct costs were estimated from hospital data and the literature. The cost per patient for the 3 vaccination strategies were: treat none, $2.00; selective, $56.00; and universal, $82.00. For every 1,000,000 patients with HCV vaccinated over a 5-year period, the selective strategy prevented 128 symptomatic cases of HAV, 3 liver transplantations, and 3 deaths owing directly to HAV compared with the treat none strategy. In addition, the selective strategy costs an additional $427,000 per patient with HAV prevented, and $23 million per HAV-related death averted, compared with the treat none strategy. The results were most sensitive to the incidence of HAV infection; vaccination increased costs if the annual rate of infection was less than 0.56% (baseline, 0.01%). Vaccination of North American patients with chronic HCV against HAV infection is not a cost-effective therapy.