Estimating the number needed to vaccinate to prevent herpes zoster-related disease, health care resource use and mortality

Updated Public Health Impact and Cost Effectiveness of Recombinant Zoster Vaccine in Canadian Adults Aged 50 Years and Older

OBJECTIVES

The aim of this study was to update previously estimated public health impact and cost effectiveness of recombinant zoster vaccine (RZV) for the prevention of herpes zoster (HZ) in Canadians aged ≥50 years using longer-term RZV efficacy and waning data and real-world coverage and completion.

METHODS

A multicohort Markov model was used to conduct a cost-utility analysis comparing RZV with no HZ vaccination among Canadians aged ≥50 years. Real-world data were used for first-dose coverage (17.5%) and second-dose completion (65%). Vaccine efficacy and waning data were applied from up to 8-year follow-up from the ZOE-50 and ZOE-70 clinical trials. Incremental costs and benefits were calculated using a lifetime horizon from the healthcare payer (base case) and societal perspectives. A discount rate of 1.5% was applied to costs and quality-adjusted life-years (QALYs).

RESULTS

The model estimated that RZV would prevent 303,835 HZ cases, 83,256 post-herpetic neuralgia (PHN) cases, 39,653 other complications, and 99 HZ-related deaths compared with no HZ vaccination. Incremental cost-effectiveness ratios (ICERs) were estimated to be $27,486 and $22,097 per QALY (2022 Canadian dollars [CAN$]) from the healthcare payer and societal perspectives, respectively. The base-case ICER was most sensitive to a lower percentage of initial HZ cases with PHN. Almost all probabilistic sensitivity analysis simulations (98.1%) resulted in ICERs

CONCLUSIONS

RZV is expected to remain a cost-effective option for Canadian adults aged ≥50 years when using longer-term RZV efficacy and waning estimates, although the estimated public health impact was smaller than in the previous analysis (due to lower coverage/completion estimates).

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Grants

• GlaxoSmithKline Biologicals

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Affiliation(s)

Sydney George GSK, Mississauga, ON, Canada.
Justin Carrico RTI Health Solutions, Research Triangle Park, NC, USA
Katherine A Hicks RTI Health Solutions, Research Triangle Park, NC, USA
Dessi Loukov GSK, Mississauga, ON, Canada
Cheryl Ng GSK, Singapore, Singapore
Jessica Regan GSK, Mississauga, ON, Canada
Nikolaos Giannelos GSK, Wavre, Belgium

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The Number Needed to Vaccinate (NNV) against herpes zoster: a systematic review with meta-analysis

OBJECTIVES

The number needed to vaccinate (NNV) quantifies the effectiveness of vaccination programs. We summarised the published data on NNV against herpes zoster to inform vaccination policies.

METHODS

We systematically identified studies based on a priori established and registered methods. The main outcomes were the NNV against herpes zoster infection, hospitalisation and mortality. Where appropriate, we conducted meta-analyses using inverse variance, random-effects models, pooling estimated NNV with associated 95% confidence interval (CI). Statistical heterogeneity between pooled estimates was calculated using the I² statistic.

RESULTS

Out of 229 unique citations, we included eight nonrandomized studies. Among 50+ year-olds, the NNV against herpes zoster infection using the recombinant subunit vaccine was 11 (95%CI 8-14; I² = 0%; 3 studies) and variable (I² = 94.4%; 7 studies) using live attenuated vaccine, ranging from 10 (95%CI 1-19) to 58 (95%CI 49-67). Among 65+ year-olds, the NNV against herpes zoster infection using the recombinant subunit vaccine was 12 (95%CI: 9-15; I² = 0%; 2 studies) and variable (I² = 98.5%; 4 studies) using live attenuated vaccine, ranging from 14 (95%CI 5-23) to 75 (95%CI 66-84). The NNV against herpes zoster hospitalisation among 65+ year-olds using the live attenuated vaccine was 280 (95%CI 209-352; I² = 0%; 2 studies). There was a paucity of data to inform other meta-analyses.

CONCLUSION

Evidence on the NNV against herpes zoster is scarce. Vaccination with the recombinant subunit herpes zoster vaccine may be more effective than with the live attenuated vaccine in preventing infection among 50+ year-olds. More studies are needed for a stronger evidence base for decision-making.

The potential population-based impact of an HPV vaccination intervention in Colorado

Background

Human papillomavirus (HPV) infection is the most common cause of cervical cancer and can be prevented with vaccination, but HPV vaccination rates remain low. An intervention to improve health care provider communication about vaccination has been shown to increase HPV vaccination rates in an initial trial in Colorado, where about 160 cases of cervical cancer are diagnosed each year.

Methods

Census data were combined with Colorado cancer and immunization registry data to identify clinics in locations that would most benefit from implementation of this intervention to improve HPV vaccination rates. ArcGIS Pro was used to map cervical cancer incidence, immunization rates, population data, and location of clinics participating in practice‐based research networks (PBRNs). Results from the provider communication intervention trial and published estimates of the number needed to vaccinate to prevent a case of cervical cancer were used to predict the number of cervical cancer cases prevented based on increased vaccination due to the intervention.

Results

Ninety‐eight Colorado PBRN clinics were analyzed. For the 10 clinics with the highest predicted number of cervical cancer cases prevented, 5218 additional patients would be vaccinated and 43 cervical cancer cases prevented with implementation of the intervention. If implemented in all 98 clinics, the intervention would lead to 20 490 additional patients vaccinated (range 7‐658/clinic) and 171 cases of cervical cancer prevented (range 0.05‐5.48/clinic).

Conclusions

Geographic data from cancer and immunization registries can inform the dissemination of evidence‐based practices like the provider communication intervention for HPV vaccination to maximize impact on public health.

Public Health Impact and Cost-Effectiveness of Non-live Adjuvanted Recombinant Zoster Vaccine in Canadian Adults

OBJECTIVES

In Canada, incidences of herpes zoster (HZ) and postherpetic neuralgia (PHN) are increasing, posing a significant burden on the healthcare system. This study aimed to determine the public health impact and cost effectiveness of an adjuvanted recombinant zoster vaccine (RZV) compared to no vaccination and to the live attenuated vaccine (ZVL) in Canadians aged 60 years and older.

METHODS

A multi-cohort Markov model has been adapted to the Canadian context using recent demographic and epidemiologic data. Simulations consisted of age-cohorts annually transitioning between health states. Health outcomes and costs were discounted at 1.5% per year. The perspective of the Canadian healthcare payer was adopted. A coverage of 80% for the first RZV and ZVL dose and a compliance of 75% for the second RZV dose were assumed.

RESULTS

RZV was estimated to be cost effective compared with no vaccination with an incremental cost-effectiveness ratio (ICER) of $28,360 (Canadian dollars) per quality-adjusted life-year (QALY) in persons aged ≥ 60 years, avoiding 554,504 HZ and 166,196 PHN cases. Compared with ZVL, RZV accrued more QALYs through the remaining lifetime and an increase in costs of approximately $50 million resulting in an average ICER of $2396. Results were robust under deterministic and probabilistic sensitivity analyses. HZ incidence rate and persistence of vaccine efficacy had the largest impact on cost effectiveness.

CONCLUSIONS

The cost-utility analysis suggested that RZV would be cost effective in the Canadian population compared with no vaccination and vaccination with ZVL at a willingness-to-pay threshold of $50,000.

Cost-effectiveness analysis of a vaccination program for the prevention of herpes zoster and post-herpetic neuralgia in adults aged 50 and over in Germany

Herpes zoster (HZ; shingles) is a common viral disease that affects the nerves and surrounding skin causing a painful dermatomal rash and leading to debilitating complications such as, mainly, post-herpetic neuralgia (PHN). Currently, there is no effective treatment for HZ and PHN. The objective of this study was to assess the cost-effectiveness of a HZ vaccination program in Germany. An existing Markov Model was adapted to the German healthcare setting to compare a vaccination policy to no vaccination on a lifetime time-horizon, considering 2 scenarios: vaccinating people starting at the age of 50 or at the age of 60 years, from the perspective of the statutory health insurance (SHI) and the societal perspective. According to the perspective, vaccinating 20% of the 60+ German population resulted in 162,713 to 186,732 HZ and 31,657 to 35,793 PHN cases avoided. Corresponding incremental cost-effectiveness ratios (ICER) were 39,306 €/QALY from the SHI perspective and 37,417 €/QALY from a societal perspective. Results for the 50+ German population ranged from 336,468 to 394,575 HZ and from 48,637 to 56,087 PHN cases avoided from the societal perspective. Corresponding ICER were 39,782 €/QALY from a SHI perspective and 32,848 €/QALY from a societal perspective. Sensitivity analyses showed that results are mainly impacted by discount rates, utility values and use of alternative epidemiological data.The model indicated that a HZ vaccination policy in Germany leads to significant public health benefits and could be a cost-effective intervention. The results were robust and consistent with local and international existing literature.

How and why researchers use the number needed to vaccinate to inform decision making--a systematic review

BACKGROUND

The number needed to vaccinate (NNV) is a measure that has been widely used in the scientific literature to draw conclusions about the usefulness and cost-effectiveness of various immunization programmes. The main objective of this review is to examine how and why the NNV has been used and reported in the published literature.

METHODS

Electronic databases were searched and records were screened against the eligibility criteria by two independent authors. We included papers that reported and interpreted NNV.

RESULTS

We identified 27 studies, the designs including observational studies, economic analyses, systematic reviews, and commentaries. The NNV has been used in the literature to describe three main themes: potential benefits of vaccination programmes, cost-effectiveness, and economic analyses, and modelling studies to compare different vaccination strategies.

CONCLUSIONS

NNV has been used in a wide variety of ways in the literature, yet there are no defined thresholds for what is a favourable NNV. Furthermore, the generalizability of the NNV is usually limited. Further work is required to determine the most appropriate use of this measure.

Is herpes zoster vaccination likely to be cost-effective in Canada?

OBJECTIVES

To synthesize the current literature detailing the cost-effectiveness of the herpes zoster (HZ) vaccine, and to provide Canadian policy-makers with cost-effectiveness measurements in a Canadian context.

METHODS

This article builds on an existing systematic review of the HZ vaccine that offers a quality assessment of 11 recent articles. We first replicated this study, and then two assessors reviewed the articles and extracted information on vaccine effectiveness, cost of HZ, other modelling assumptions and QALY estimates. Then we transformed the results into a format useful for Canadian policy decisions. Results expressed in different currencies from different years were converted into 2012 Canadian dollars using Bank of Canada exchange rates and a Consumer Price Index deflator. Modelling assumptions that varied between studies were synthesized. We tabled the results for comparability.

SYNTHESIS

The Szucs systematic review presented a thorough methodological assessment of the relevant literature. However, the various studies presented results in a variety of currencies, and based their analyses on disparate methodological assumptions. Most of the current literature uses Markov chain models to estimate HZ prevalence. Cost assumptions, discount rate assumptions, assumptions about vaccine efficacy and waning and epidemiological assumptions drove variation in the outcomes. This article transforms the results into a table easily understood by policy-makers.

CONCLUSION

The majority of the current literature shows that HZ vaccination is cost-effective at the price of $100,000 per QALY. Few studies showed that vaccination cost-effectiveness was higher than this threshold, and only under conservative assumptions. Cost-effectiveness was sensitive to vaccine price and discount rate.

A cocoon immunisation strategy against pertussis for infants: does it make sense for Ontario?

Pertussis deaths occur primarily among infants who have not been fully immunised. In Ontario, Canada, an adult booster dose was recently added to the publicly funded immunisation programme. We applied number-needed-to-treat analyses to estimate the number of adults that would need to be vaccinated (NNV) to prevent pertussis disease, hospitalisation and death among infants if a cocoon strategy were implemented. NNV=1/(P(M) X R) + 1/(P(F) X R), where P(M),P(F) (proportion of infants infected by mothers, fathers) were sourced from several studies. Rates of disease, hospitalisation or death (R) were derived from Ontario's reportable disease data and Discharge Abstract Database. After adjusting for under-reporting, the NNV to prevent one case, hospitalisation or death from pertussis was between 500-6,400, 12,000-63,000 and 1.1-12.8 million, respectively. Without adjustment, NNV increased to 5,000-60,000, 55,000-297,000 and 2.5-30.2 million, respectively. Rarer outcomes were associated with higher NNV. These analyses demonstrate the relative inefficiency of a cocoon strategy in Ontario, which has a well-established universal immunisation programme with relatively high coverage and low disease incidence. Other jurisdictions considering a cocoon programme should consider their local epidemiology.

Epidemiology and cost of herpes zoster and postherpetic neuralgia in Germany

After acquiring a varicella virus infection, the virus can reactivate and cause herpes zoster (HZ)--a painful skin rash. A complication of HZ is long-term persistence of pain after the rash has resolved (so-called postherpetic neuralgia, PHN). We aimed to describe the epidemiology of HZ/PHN and to estimate HZ/PHN-related costs in the German statutory health insurance (SHI) system (~85% of the total population). Treatment data of one large SHI was utilized, containing data on approximately 240,000 insured and their utilisation of services in 2004-2009. Identification of HZ- and PHN-cases was performed based on 'International Statistical Classification of Diseases' and specific medications using a control-group design. Incidences per 1,000 person-years (PY) and cost-of-illness for 1 year following HZ-onset considering the payer and societal perspective were calculated. All amounts were inflated to 2010 Euros. Population-figures were standardised and extrapolated to the total SHI-population in Germany in 2010. A mean annual incidence of 5.79 HZ-cases per 1,000 PY was observed, translating into an estimated 403,625 HZ-cases per year in the total SHI-population. Approximately 5% of HZ-cases developed PHN. One HZ-case caused on average euro 210 and euro 376 of costs from the payer and societal perspective, respectively. The development of PHN generated additional costs of euro 1,123 (euro 1,645 societal perspective). Total annual HZ/PHN-related costs were estimated at euro 182 million (euro 105 million) to society (payer). HZ and PHN place a considerable burden on the German SHI-system. Since HZ-vaccines will soon be available, a health-economic evaluation of these vaccines should be conducted.

Health economic evaluation of vaccination strategies for the prevention of herpes zoster and postherpetic neuralgia in Germany

BACKGROUND

Herpes zoster (HZ) is a self-limiting painful skin rash affecting mostly individuals from 50 years of age. The main complication is postherpetic neuralgia (PHN), a long-lasting pain after rash has resolved. A HZ-vaccine has recently been licensed in Europe for individuals older than 50 years. To support an informed decision-making for a potential vaccination recommendation, we conducted a health economic evaluation to identify the most cost-effective vaccination strategy.

METHODS

We developed a static Markov-cohort model, which compared a vaccine-scenario with no vaccination. The cohort entering the model was 50 years of age, vaccinated at age 60, and stayed over life-time in the model. Transition probabilities were based on HZ/PHN-epidemiology and demographic data from Germany, as well as vaccine efficacy (VE) data from clinical trials. Costs for vaccination and HZ/PHN-treatment (in Euros; 2010), as well as outcomes were discounted equally with 3% p.a. We accounted results from both, payer and societal perspective. We calculated benefit-cost-ratio (BCR), number-needed-to-vaccinate (NNV), and incremental cost-effectiveness ratios (ICERs) for costs per HZ-case avoided, per PHN-case avoided, and per quality-adjusted life-year (QALY) gained. Different target age-groups were compared to identify the most cost-effective vaccination strategy. Base-case-analysis as well as structural, descriptive-, and probabilistic-sensitivity-analyses (DSA, PSA) were performed.

RESULTS

When vaccinating 20% of a cohort of 1 million 50 year old individuals at the age of 60 years, approximately 20,000 HZ-cases will be avoided over life-time. The NNV to avoid one HZ (PHN)-case was 10 (144). However, with a BCR of 0.34 this vaccination-strategy did not save costs. The base-case-analysis yielded an ICER of 1,419 (20,809) Euros per avoided HZ (PHN)-case and 28,146 Euros per QALY gained. Vaccination at the age of 60 was identified in most (sensitivity) analyses to be the most cost-effective vaccination strategy. In DSA, vaccine price and VE were shown to be the most critical input-data.

CONCLUSIONS

According to our evaluation, HZ-vaccination is expected to avoid HZ/PHN-cases and gain QALYs to higher costs. However, the vaccine price had the highest impact on the ICERs. Among different scenarios, targeting individuals aged 60 years seems to represent the most cost-effective vaccination-strategy.

Review of the United States universal varicella vaccination program: Herpes zoster incidence rates, cost-effectiveness, and vaccine efficacy based primarily on the Antelope Valley Varicella Active Surveillance Project data

In a cooperative agreement starting January 1995, prior to the FDA's licensure of the varicella vaccine on March 17, the Centers for Disease Control and Prevention (CDC) funded the Los Angeles Department of Health Services' Antelope Valley Varicella Active Surveillance Project (AV-VASP). Since only varicella case reports were gathered, baseline incidence data for herpes zoster (HZ) or shingles was lacking. Varicella case reports decreased 72%, from 2834 in 1995 to 836 in 2000 at which time approximately 50% of children under 10 years of age had been vaccinated. Starting in 2000, HZ surveillance was added to the project. By 2002, notable increases in HZ incidence rates were reported among both children and adults with a prior history of natural varicella. However, CDC authorities still claimed that no increase in HZ had occurred in any US surveillance site. The basic assumptions inherent to the varicella cost-benefit analysis ignored the significance of exogenous boosting caused by those shedding wild-type VZV. Also ignored was the morbidity associated with even rare serious events following varicella vaccination as well as the morbidity from increasing cases of HZ among adults. Vaccine efficacy declined below 80% in 2001. By 2006, because 20% of vaccinees were experiencing breakthrough varicella and vaccine-induced protection was waning, the CDC recommended a booster dose for children and, in 2007, a shingles vaccination was approved for adults aged 60 years and older. In the prelicensure era, 95% of adults experienced natural chickenpox (usually as children)-these cases were usually benign and resulted in long-term immunity. Varicella vaccination is less effective than the natural immunity that existed in prevaccine communities. Universal varicella vaccination has not proven to be cost-effective as increased HZ morbidity has disproportionately offset cost savings associated with reductions in varicella disease. Universal varicella vaccination has failed to provide long-term protection from VZV disease.

Update on herpes zoster vaccination: a family practitioner's guide

OBJECTIVE

To answer frequently asked questions surrounding the use of the new herpes zoster (HZ) vaccine.

SOURCES OF INFORMATION

Published results of clinical trials and other studies, recommendations from the Canadian National Advisory Committee on Immunization, and the US Advisory Committee on Immunization Practices; data were also obtained from the vaccine's Health Canada-approved product monograph.

MAIN MESSAGE

Herpes zoster results from reactivation of the varicella-zoster virus; postherpetic neuralgia (PHN) is its most common and serious complication. The incidence of PHN after HZ is directly related to age, with 50% of affected individuals older than 60 years experiencing persistent and unrelieved pain. The live virus HZ vaccine reduces the incidence of HZ by about 50% and the occurrence of PHN by two-thirds, with vaccinated individuals experiencing attenuated or shortened symptoms. The vaccine is contraindicated in many immunocompromised patients and might not be effective in patients taking antiviral medications active against the HZ virus. Physicians should be aware of the different recommendations for these groups.

CONCLUSION

The HZ vaccine is a safe and effective preventive measure for reducing the overall burden and severity of HZ in older adults. The vaccine appears to be cost-effective when administered to adults aged 60 years and older.

A refresher on herpes zoster, current status on vaccination, and the role of the dermatologist

BACKGROUND

Herpes zoster (HZ) and postherpetic neuralgia (PHN) have a significant impact on quality of life. PHN is often chronic and difficult to treat. Dermatologists have always been involved in making the diagnosis of these conditions and, most recently, teaching the need for early antiviral therapy.

OBJECTIVE

With the introduction of a new vaccine, HZ and its difficult-to-treat complication PHN can be prevented or minimized. Preventive medicine is important and has been supported by dermatologists with sun safety programs. Patients receiving biologics are at increased risk of developing zoster.

CONCLUSION

Dermatologists should embrace zoster vaccination and recommend routine vaccination of immunocompetent individuals > age 60 years, as well as patients of any age who are starting immunosuppressants, including biologics. Given that individuals over age 50 years are at risk for PHN and studies have shown that the vaccine's immunogenicity and safety are maintained in individuals age 50 to 59 years, vaccination in this age group may be considered. Some dermatologists may consider vaccinating their own patients, but most will likely recommend that vaccination be performed by their patients' primary care physicians.

Herpes zoster in Germany: quantifying the burden of disease

BACKGROUND

Herpes zoster (HZ) is caused by a reactivation of the varicella-zoster-virus (VZV) and mainly affects individuals aged≥50 years. Vaccines have been licensed or are under development that can protect against HZ and its main complication postherpetic neuralgia (PHN). In Germany, the burden of disease caused by HZ is not well known. To support the decision making process related to a potential vaccination recommendation, we estimated annual HZ disease burden in people aged≥50 years in Germany by utilizing various data sources.

METHODS

We assessed for 2007 and 2008 HZ-outpatient incidence (number of cases per 1,000 person-years, PY) by utilizing the Association of Statutory Health Insurance Physicians (ASHIP) database, which contains nationwide routine outpatient data. For the same time period annual number of HZ-inpatients and HZ-associated deaths were identified by using the Federal Health Monitoring System (FHM). PHN-incidence and loss of quality-adjusted life years (QALYs) caused by HZ were calculated by multiplying number of identified HZ-patients with upper and lower limit estimates for proportion of HZ-cases developing PHN and HZ-related QALY, respectively.

RESULTS

For the study period we identified an annual average of 306,511 HZ-outpatients aged 50+, resulting in a HZ-incidence of 9.6/1,000 PY. A total 14,249 HZ-associated inpatients and 66 deaths were reported in both years on average. HZ-incidence increased by age from 6.21 in people 50-54 years to 13.19 per 1,000 PY in people aged≥90 years. Females were significantly more frequently affected than males in terms of outpatient HZ-incidence (11.12 vs. 7.8 per 1,000 PY), inpatient HZ-incidence (0.51 vs. 0.38 per 1,000 PY) and mortality (0.29 vs. 0.10 per 100,000 PY). PHN-incidence was estimated to range between 0.43 and 1.33 per 1,000 PY. Based on these figures, there were between 3,065 to 24,094 QALYs lost due to HZ in persons aged≥50 years in Germany per annum.

CONCLUSION

Our study provides important baseline estimates for HZ-related disease burden in Germany. HZ poses a considerable burden on the health care system in Germany both in terms of outpatient and inpatient services. Follow-up assessments of HZ disease burden are needed to monitor the impact of VZV-vaccinations in Germany.