Cost effectiveness of vaccination strategies in adults without a history of chickenpox

Systematic review of economic evaluations of varicella vaccination programmes

OBJECTIVES

This study carried out a systematic literature review of economic evaluations of varicella vaccination programmes from the earliest publication to the present day, including programmes in the workplace and in special risk groups as well as universal childhood vaccination and catch up programmes.

METHODS

Articles published from 1985 until 2022 were sourced from PubMed/Medline, Embase, Web of Science, NHSEED and Econlit. Eligible economic evaluations, which included posters and conference abstracts, were identified by two reviewers who scrutinised each other's selections at both title and abstract and full report stages. The studies are described in terms of their methodological characteristics. Their results are aggregated by type of vaccination programme and the nature of the economic outcome.

RESULTS

A total of 2575 articles were identified of which 79 qualified as economic evaluations. A total of 55 studies focused on universal childhood vaccination, 10 on the workplace and 14 on high risk groups. Twenty-seven studies reported estimates of incremental cost per quality-adjusted life year (QALY) gained, 16 reported benefit-cost ratios, 20 reported cost-effectiveness outcomes in terms of incremental cost per event or life saved and 16 reported cost-cost offset results. Most studies of universal childhood vaccination reported an increase in overall costs to health services, but often a reduction in cost from a societal perspective.

CONCLUSIONS

The evidence surrounding the cost-effectiveness of varicella vaccination programmes remains sparse with contrasting conclusions in some areas. Future research should particularly aim to encompass the impact of universal childhood vaccination programmes on herpes zoster among adults.

Serological Susceptibility to Varicella Among U.S. Immigration and Customs Enforcement Detainees

U.S. Immigration and Customs Enforcement (ICE) is responsible for detaining unauthorized aliens during immigration proceedings. During 2014 to 2015, adult ICE detainees at a California facility were invited to complete a survey concerning self-reported varicella history and risk factors. Participants underwent serological testing for varicella-zoster virus (VZV) IgG; susceptible individuals were offered varicella vaccination. Among 400 detainees with available serology results, 48 (12%) were susceptible to varicella. Self-reported varicella history was negatively associated with susceptibility (adjusted odds ratio = 0.16; 95% confidence interval [0.07, 0.35]). Among 196 detainees reporting a positive history, 95% had VZV IgG levels suggestive of varicella immunity. Among 44 susceptible detainees offered vaccination, 86% accepted. Given relatively high varicella susceptibility, targeted screening and vaccination among ICE detainees lacking a positive history might reduce varicella transmission risks.

Validity of medical record documented varicella-zoster virus among unvaccinated cohorts

BACKGROUND

A varicella diagnosis or verification of disease history by any healthcare provider is currently accepted for determining evidence of immunity by the Advisory Committee on Immunization Practices (ACIP).

OBJECTIVE

To examine the accuracy of medical record (MR) documented varicella history as a measure of varicella-zoster virus (VZV) immunity among unvaccinated individuals born after 1980. We also assessed methods to practically implement ACIP guidelines to verify varicella history using medical records.

STUDY DESIGN

As part of a larger cross-sectional study conducted at three Philadelphia clinics from 2004-2006, we recruited 536 unvaccinated patients aged 5-19 y (birth years: 1985-2001). Varicella history was obtained from three sources: parent/patient interview, any MR documentation (sick and well visits) and MR documentation of a sick visit for varicella. All participants were tested for VZV IgG. For each source and three age groups (5-9, 10-14, 15-19 y old), positive predictive value (PPV) was calculated. Specificity of varicella history was compared between different sources using McNemar's Chi-square.

RESULTS

Among participants aged 5-9, 10-14 and 15-19 y the PPV for any MR documentation and sick visit diagnosis were 96% and 100%, 92% and 97%, and 99% and 100%, respectively. The specificity for sick visit documentation was higher than any MR documentation and patient/parent recall among all age groups; however, these differences were only statistically significant when comparing sick visit documentation to parent/patient recall for 10-14 y olds.

CONCLUSION

Sick visit documentation of varicella in the MR is an accurate predictor of varicella seropositivity and useful for confirming disease history among unvaccinated persons (birth years: 1985-2001). This method is a practical way to verify varicella history using the ACIP guidelines.

Management and control of varicella on cruise ships: a collaborative approach to promoting public health

BACKGROUND

In most years varicella is the vaccine-preventable disease most frequently reported to Centers for Disease Control and Prevention (CDC) by cruise ships. Since 2005, CDC has received numerous isolated case reports of varicella among crew members and has investigated varicella outbreaks aboard vessels sailing into and from US seaports.

METHODS

CDC investigators reviewed electronic varicella case reports from 2005 to 2009 and outbreak reports from 2009 to characterize the response and control efforts implemented by cruise ships in accordance with CDC protocols. Outbreak reports from 2009 were manually reviewed for details of case identification, contact investigations, isolation and restriction of cases and contacts, respectively, and number of contacts administered varicella vaccine post-exposure by cruise lines.

RESULTS

During 2005 to 2009, cruise ships reported 278 cases of varicella to CDC among predominantly male (80%) crew members, three-quarters of whom were residents of Caribbean countries, Indonesia, the Philippines, or India, and whose median age was 29 years. Cases were more commonly reported during spring and winter months. During 2009, cruise ships reported 94 varicella cases among crew members of which 66 (70%) were associated with 18 reported varicella outbreaks. Outbreak response included isolation of 66 (100%) of 66 cases, restriction of 66 (26%) of 255 crew-contacts, and administration of post-exposure vaccine to 522 close contacts and other susceptible crew members per standard CDC recommendations.

DISCUSSION

Most cases reported to CDC during 2005 to 2009 were among non-US resident crew members. Overall, cruise lines sailing into North America have the onboard capability to manage varicella cases and outbreaks and appear responsive to CDC recommendations. Cruise lines should continue to implement CDC-recommended response protocols to curtail outbreaks rapidly and should consider whether pre-placement varicella immunity screening and vaccination of crew members is a cost-effective option for their respective fleet operations.

The health and economic burden of chickenpox and herpes zoster in Belgium

Varicella-zoster virus causes chickenpox (CP) and after reactivation herpes zoster (HZ). Vaccines are available against both diseases warranting an assessment of the pre-vaccination burden of disease. We collected data from relevant Belgian databases and performed five surveys of CP and HZ patients. The rates at which a general practitioner is visited at least once for CP and HZ are 346 and 378/100 000 person-years, respectively. The average CP and HZ hospitalization rates are 5·3 and 14·2/100 000 person-years respectively. The direct medical cost for HZ is about twice as large as the direct medical cost for CP. The quality-adjusted life years lost for ambulatory CP patients consulting a physician is more than double that of those not consulting a physician (0·010 vs. 0·004). In conclusion, both diseases cause a substantial burden in Belgium.

Validity of reported varicella history as a marker for varicella zoster virus immunity among unvaccinated children, adolescents, and young adults in the post-vaccine licensure era

OBJECTIVES

We assessed the validity of reported varicella history as a marker for varicella zoster virus immunity among unvaccinated persons 1 to 29 years of age, and we examined varicella disease characteristics associated with varicella zoster virus immunity among those reporting positive histories.

METHODS

We conducted a cross-sectional study at 7 community-based sites in Philadelphia, Pennsylvania, between June 2004 and May 2006 and recruited 1476 participants 1 to 29 years of age who had not been vaccinated against varicella. Sensitivity, specificity, and positive predictive value were determined by comparing self-reported or parent-reported varicella histories from a standardized study interview with varicella zoster virus immunoglobulin G serological results for each participant. We performed multivariate logistic regression analyses to determine which disease characteristics best predicted seropositivity.

RESULTS

The sensitivity of reported varicella history was highest (81%-89%) among participants > or =10 years of age, whereas specificity was highest among participants 1 to 4 years of age (99%) and > or =20 years (88%). Reported varicella history was highly predictive of seropositivity (>95%) only among participants > or =15 years of age. For participants 10 to 14 years of age, parental reports of a generalized itchy rash with 1 of the following were highly predictive of seropositivity: varicella transmission to another household member or being raised in a household with no other children. Among participants < or =9 years of age, no combination of disease characteristics was both highly predictive of seropositivity and common.

CONCLUSIONS

The validity of reported varicella history varies according to age, and a reported history is no longer highly predictive of seropositivity among cohorts born since 1994 (participants < or =9 years of age). Universal varicella vaccination, regardless of history, for these children should be considered, as should simplified criteria for varicella zoster virus immunity among unvaccinated persons born before 1994.

Cost-effectiveness of varicella vaccination programs: an update of the literature

Varicella is one of the most common infectious diseases in childhood, caused by the varicella zoster virus. Although vaccines are available, there are only a few countries with an early-childhood vaccination program. Most countries mainly focus on vaccination of high-risk groups, such as susceptible healthcare workers. One of the main concerns with a routine early-childhood vaccination program is a potential (temporal) increase of the incidence of herpes zoster among elderly adults. In this review, we focus on the cost-effectiveness of varicella vaccination and on the methodology used in the health-economic studies. In particular, we focus on the perspective adopted, type of model used, the modeled effect on herpes zoster, the vaccine efficacy and price, and on the value of time lost by infection. The vast majority of studies show vaccination of high-risk groups - including susceptible adolescents - to be cost saving. Routine early-childhood vaccination programs are always cost saving if indirect costs of production losses are included, or cost effective, as long as the potential negative effects on zoster are not taken into account. We note that most studies included in the review used old vaccine prices and a single dose of the varicella vaccine, whereas multiple doses are now becoming the standard. Despite that, those aspects limit the timeliness of our review and we believe that the current work does provide useful insights in the cost-effectiveness of varicella vaccination.

The cost-effectiveness of mycophenolate mofetil as firstline therapy in active lupus nephritis

OBJECTIVES

Systemic lupus erythematosus (SLE) is an autoimmune disorder that can affect any system of the body. Involvement of the kidneys, lupus nephritis (LN), affects up to 50% of SLE patients during the course of their disease, and is characterized by periods of active disease (flares) and remission. For more severe nephritis, an induction course of immunosuppressive therapy is recommended. Options include intravenous cyclophosphamide (IVC) or mycophenolate mofetil (MMF), followed by a maintenance course, typically of azathioprine. The objective of this study is to determine which therapy results in better quality of life (QoL) for patients and which represents best value for money for finite health service resources.

METHODS

A patient-level simulation model is developed to estimate the costs and quality-adjusted life-years (QALYs) of a patient treated with IVC or MMF for an induction period of six months. Efficacy, QoL, resource use and cost data are extracted from the literature and standard databases and supplemented with expert opinion where necessary.

RESULTS

On average, the model predicts MMF to result in improved QoL compared with IVC. MMF is also less expensive than IVC, costing pound 1600 (euro 2400; US$ 3100) less over the period, based on 2005 NHS prices. The major determinant and cost driver of this result is the requirement for a day-case procedure to administer IVC. Sensitivity analysis shows an 81% probability that MMF will be cost-effective compared with IVC at a willingness to pay of pound 30,000 (euro 44,700; US$ 58,500) per QALY gained.

CONCLUSION

MMF is likely to result in better QoL and be less expensive than IVC as induction therapy for LN.

Assessing the introduction of universal varicella vaccination in the Netherlands

Although varicella is seen as a benign disease in the Netherlands, about 40,000 visits to a general practitioner (GP) are made, over 200 hospital admission occur, and 2.3 persons die on average each year. Most of this burden of disease can be prevented by universal varicella childhood vaccination. Ten years after the introduction of the single-shot, single-component varicella childhood vaccination in the USA, a major reduction in hospitalization, mortality, and burden of disease has been reported. Using our recently vaccine evaluation model for the introduction of a new vaccine in our national immunization program, we have analyzed the feasibility of universal varicella vaccination by replacing the measles-mumps-rubella (MMR) vaccine with a measles-mumps-rubella-varicella (MMRV) vaccine. After structuring and reviewing the available data, two major points of uncertainty remain: (1) the influence of universal childhood vaccination on the incidence of zoster later in life; (2) the cost-effectiveness ratio for the Dutch situation. Despite these uncertainties it is clear that universal childhood vaccination will prevent most of the varicella related GP-visits, hospitalizations, and deaths.

Cost-effectiveness of varicella vaccination of healthcare workers

OBJECTIVE

Although transmission of VZV is recognized as an important cause for morbidity in health care workers (HCWs), there is no general agreement on the recommended immunization policy. This study aimed to evaluate several of such prevention policies in economic terms.

SETTINGS

Analysis of the cost per avoided future varicella cases among HCWs in Israel.

METHODS

A cost-effectiveness analysis was performed by comparing the cost per avoided case of varicella among a theoretical cohort of 63,353 physician and nurses aged less than 45 years in Israel. Four policies were examined: (a) do nothing (status quo); (b) vaccination of susceptible workers using VZV serotesting; with (c) or without anamnestic history of chickenpox; and (d) presumptive mass vaccination of all eligible workers. A Markov-based model was developed using data from our recent seroepidemiological study in target population and from the literature.

RESULTS

Screening and vaccination of susceptible workers using anamnestic selection is expected to reduce future cases, within 20 years since vaccination, from 58.3 to 33.0 with an incremental cost of 23,713 US dollars per avoided cases. Using only serological tests to detect susceptible workers would prevent additional 5.7 cases with an incremental cost of 206,692 US dollars per avoided case. Vaccinating all HCWs without serotesting, raises the costs markedly, with almost identical effectiveness, resulting in an incremental cost of 10.4 million US dollars per avoided case. Sensitivity analyses do not alter the ranking of the options.

CONCLUSION

From the employer's perspective, routine varicella vaccination program for HCWs with or without selection of susceptible workers is extremely expensive compared to other high-cost practiced approaches. Substantial reduction in cost of vaccination may alter this conclusion.

Comparison of varicella history with presence of varicella antibody in refugees

OBJECTIVE

To compare history of varicella with presence of varicella antibody in refugees and to determine the number of unnecessary doses of varicella vaccine administered to refugee children > or =7 years of age.

METHODS

Cross-sectional study of refugees > or =7 years of age evaluated between July 2000 and October 2002 by the Refugee Health Assessment Program at Boston Medical Center. We recorded age, sex, region of origin, varicella history, and results of serologic testing for presence of varicella antibodies.

RESULTS

Eighty-eight percent of individuals with a positive history of clinical varicella had varicella antibody; 65% of those with negative history had varicella antibody. The positive predictive value of a history of clinical varicella was 88%. The negative predictive value of a negative history was 39%.

CONCLUSION

History of varicella was not a reliable predictor of presence or absence of varicella antibody in refugees. Strategies to protect individuals with negative histories of clinical varicella include immediate immunization or serotesting followed by immunization of susceptible individuals. Relying on positive histories of clinical varicella may leave some individuals susceptible to varicella and impede efforts to eliminate varicella in the US.

Cost containment analysis of childhood vaccination against varicella in Israel

OBJECTIVES

The low cost of safe and effective vaccines prompted a cost-containment evaluation of a nationwide vaccination campaign against varicella.

METHODS

A model incorporating demographic, epidemiologic and economic data from Israeli sources (supplemented by data from International literature) was constructed to estimate the decrease in morbidity and the consequent reductions in treatment costs and time-off work of a nationwide programme vaccinating children at 12 months.

RESULTS

A policy of aiming to immunize a cohort of all 1-year-olds in Israel in the year 2002, for an annual cost of $1.10 million to the health services and $1.27 million to society (including lost work and transport costs), would reduce the number of cases of varicella during the lifetime of a cohort from 123,984 to 10,170 cases. This morbidity reduction would reduce national expenditures by $1.80 million in health service resources alone and by $24.5 million to society, mainly due to inaverted work absences. In addition an estimated 0.93 lives, representing 38.6 life years will be saved in the cohort.

CONCLUSIONS

Under an assumption of neutrality relating to the potential effects of vaccination on herpes zoster virus, our model based calculations show that a national varicella vaccination programme is likely to be cost saving, not only from a societal perspective but also from the narrower health service perspective.

Varicella in French adolescents and adults: individual risk assessment and cost-effectiveness of routine vaccination

Age-specific force of varicella infection, hospitalisation and death rates in non-immune persons were calculated using an age-based mathematical model and national data for France. A cost-effectiveness model was then applied to hypothetical cohorts of persons aged 15-45 years with a negative or uncertain history of varicella. Vaccination strategies with and without prior serotesting, and healthcare payer perspective and societal perspective were considered. A sensitivity analysis was performed. Vaccination prevented more than one third of all varicella-related deaths. With serotesting, compared with no intervention, the cost per case avoided and per year of life saved for subjects aged 15 years were 335 and 55,100 Euro, respectively. When work-loss costs were also included, savings were associated with screening and vaccination of subjects less than 30 years old. Without serotesting, the costs raised markedly, with an almost identical effectiveness, resulting in an unfavourable incremental cost-effectiveness. Based on medical costs, routine serotesting and varicella vaccination for French adolescents and young adults with a negative or uncertain history of varicella affords health benefits at a cost comparable to those of other very expensive therapies considered worthwhile. From the societal perspective, such screening and vaccination might save costs.

[Chickenpox outbreak in Herrera del Duque, Badajoz, Spain]

INTRODUCTION

Chickenpox is a worldwide disease with high morbidity but few complications, although complications can be sevre in immunocompromised individuals and healthy adults. The annual chickenpox rate declared to the National Notification Disease Surveillance System is approximately 5 cases per 1,000 inhabitants in Extremadura (Spain). The aim of this study was to identify and describe the characteristics and cost of an epidemic outbreak of chickenpox in Extremadura.

METHODS

Between November 2000 and March 2001, a descriptive study was performed. Cases of chickenpox were actively sought in a cohort of schoolchildren in Herrera del Duque (Badajoz). The protocols of the Monitoring Network of the Autonomous Community of Extremadura was used for case definition. Microbiological confirmation was performed by isolation of the virus and the presence of IgM and IgG markers in serum. We analyzed the direct and indirect tangible costs as well as the intangible costs of the outbreak.

RESULTS

Seventy-five cases were identified, of which 94.7% occurred in children aged between 1-9 years, mainly boys. The attack rate was 18.5 cases per 1,000 inhabitants and 68.2% occurred in children aged less than 10 years charing a home. The clinical course was benign, without hospital admissions or complications. A total of 71.6% of children aged between 3 and 8 years were susceptible. A possible temporary aggregation of cases in the school was analyzed and a relative risk of 5.01 (p < 0.0001) was obtained. The virus was isolated in the 4 vesicle samples studied and serology was positive (IgM) in the 9 serum samples studied. The total cost of the outbreak was of 927,21 e, with a mean of 12,53 e per case and 205 school days lost.

CONCLUSION

A chickenpox outbreack was confirmed in Herrera del Duque, with person-to-person transmission, affecting children aged between 1 and 9 years. The high susceptibility of the pupils, the characteristics of teaching, and the meetings prior to the carnivals played a determining role in the transmission of the epidemic. The estimated cost of this outbreak was 76% less than the cost that would have been generated by single-dose vaccination of the 75 individuals who contracted the disease.