Vaccination against herpes zoster in developed countries: state of the evidence

Incidence and Burden of Herpes Zoster in Sweden: A Regional Population-Based Register Study

INTRODUCTION

Herpes zoster (HZ) is a painful disease that mainly affects individuals whose immune system has been weakened because of increasing age (> 50 years) or certain diseases or treatments. We estimated the complete burden of HZ.

METHODS

This population-based register study analysed healthcare data from the VEGA and Digitalis databases of Västra Götaland Region (VGR), Sweden. The VEGA database includes all patients in VGR, covering both hospital and primary care. The Digitalis records prescribed medications. The study population included patients aged ≥ 18 years with at least one registered primary or secondary HZ diagnosis (based on International Classification of Diseases [ICD] codes) between 2005 and 2021. Incidence rates (95% confidence intervals [CI]) were stratified by age, sex and diagnosis/analgesic prescription.

RESULTS

Overall HZ incidence increased from 2.5 (95% CI 2.4-2.6) in 2005 to 4.2 (95% CI 4.1-4.3) in 2021. The increase in incidence was rapid from 2005 to 2013, followed by a plateauing trend. From 2014-2019, the lifetime risk of HZ, excluding recurrent cases, was 36.5% (95% CI 35.5-37.4%). Municipal differences ranged from 34.4% (95% CI 32.5-36.4%) to 43.6% (95% CI 39.9-47.4%). Recurrence rates of HZ were 8.7% and 9.1% with follow-up periods of 5.5 and 10.5 years, respectively. Reported postherpetic neuralgia (PHN) cases increased five-fold over the study period. In 2019, 19% of all HZ patients developed HZ-related neuropathic pain; 13.6% had signs of persistent pain (> 90 days; i.e. PHN). An increased occurrence of cerebral and cardiovascular disease was observed in HZ patients. Among high-risk groups the occurrence of HZ peaked among those with inflammatory and autoimmune diseases.

CONCLUSION

HZ and PHN risk in Sweden is comparable to that in other European countries prior to implementing HZ national vaccination programs. Municipal differences suggest that the lifetime risk of HZ in Sweden is at least 36.5%.

CLINICAL TRIAL REGISTRATION

NCT Number ( www.

CLINICALTRIALS

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Herpes Zoster and Long-Term Risk of Cardiovascular Disease

Background We investigated the longitudinal association of herpes zoster (HZ), commonly known as "shingles," and long-term risk of stroke or coronary heart disease (CHD) among participants in 3 large US cohorts, the NHS (Nurses' Health Study), NHS II (Nurses' Health Study II), and HPFS (Health Professionals Follow-Up Study). Methods and Results Participants were 79 658 women in the NHS (2000-2016), 93 932 women in the NHS II (2001-2017), and 31 440 men in the HPFS (2004-2016), without prior stroke or CHD. Information on HZ, stroke, and CHD was collected on biennial questionnaires and confirmed by medical record review. Cox proportional hazards regression models were used to estimate multivariable-adjusted hazard ratios for stroke and for CHD according to years since HZ compared with never HZ. During >2 million person-years of follow-up, 3603 incident stroke and 8620 incident CHD cases were documented. History of HZ was significantly and independently associated with higher long-term risk of stroke and CHD. In pooled analyses, compared with individuals with no history of HZ, the multivariable-adjusted hazard ratios (95% CIs) for stroke were 1.05 (0.88-1.25) among those with 1 to 4 years since HZ, 1.38 (1.10-1.74) for among those with 5 to 8 years since HZ, 1.28 (1.03-1.59) among those with for 9 to 12 years since HZ, and 1.19 (0.90-1.56) among those with ≥13 years since HZ. For CHD, the corresponding multivariable-adjusted hazard ratios (95% CIs) were 1.13 (1.01-1.27) for 1 to 4 years, 1.16 (1.02-1.32) for 5 to 8 years, 1.25 (1.07-1.46) for 9 to 12 years, and 1.00 (0.83-1.21) for ≥13 years. Conclusions HZ is associated with higher long-term risk of a major cardiovascular event. These findings suggest there are long-term implications of HZ and underscore the importance of prevention.

Global herpes zoster incidence, burden of disease, and vaccine availability: a narrative review

Herpes zoster (HZ) is a neurocutaneous disease that causes significant morbidity worldwide. The disease is caused by the reactivation of the varicella-zoster virus (VZV), which leads to the development of a painful, vesicular rash and can cause complications such as post-herpetic neuralgia and vision loss. Globally, the incidence of HZ is increasing, and it incurs billions in cost annually to the healthcare system and to society through loss of productivity. With the advent of effective vaccines such as the live attenuated vaccine, Zostavax®, in 2006, and more recently the adjuvant recombinant subunit vaccine, Shingrix®, in 2017, HZ has become a preventable disease. However, access to the vaccines remains mostly limited to countries with developed economies, such as the United States and Canada. Even among countries with developed economies that license the vaccine, few have implemented HZ vaccination into their national immunization schedules due to cost-effectiveness considerations. In this review, we discuss the currently available HZ vaccines, landscape of HZ vaccine guidelines, and economic burden of disease in countries with developed and developing economies, as well as barriers and considerations in HZ vaccine access on a global scale.

Infections in the older population: what do we know?

The incidence of infections increases with age and results in a higher risk of morbidity and mortality. This rise is not mainly related to chronological age per se but has been linked mostly to individual factors such as immunosenescence; the presence of comorbidities; the occurrence of geriatric syndromes such as poor nutrition, polypharmacy, and cognitive disorders; and the presence of functional impairment concomitant with environmental, healthcare-related and microbiological factors such as the increasing risk of multidrug-resistant microorganisms. The geriatric concept of frailty introduces a new approach for considering the risk of infection; this concept highlights the importance of functional status and is a more comprehensive and multicomponent approach that may help to reverse the vulnerability to stress. The aim of this article is to provide some typical hallmarks of infections among older adults in comparison to younger individuals. The main differences among the older population that are presented are an increased prevalence of infections and potential risk factors, a higher risk of carrying multidrug-resistant microorganisms, an increase in barriers to a prompt diagnosis related to atypical presentations and challenges with diagnostic tools, a higher risk of under- and over-diagnosis, a worse prognosis with a higher risk of acute and chronic complications and a particular need for better communication among all healthcare sectors as they are closely linked together.

Effectiveness and cost-effectiveness of vaccination against herpes zoster in Canada: a modelling study

BACKGROUND

Two vaccines against herpes zoster are currently authorized for use in Canada: the recombinant subunit zoster vaccine and live attenuated zoster vaccine. We compared the effectiveness and cost-effectiveness of these 2 vaccines.

METHODS

We used a decision analytic static cohort model parametrized with Canadian epidemiologic and economic data. We performed the economic analysis from the health care system perspective, using a lifetime horizon and a 3% discount rate for costs and benefits. The primary outcome was the incremental cost per quality-adjusted life-year (QALY) gained, relative to no vaccination. We ran 30 000 simulations varying all model parameters, including vaccine costs, efficacy and waning.

RESULTS

The number needed to vaccinate (NNV) was higher for the live attenuated zoster vaccine than for the recombinant subunit zoster vaccine for all herpes zoster-related events at all ages. For example, in persons exactly 65 years old, for herpes zoster, median NNV was 21 (90% uncertainty interval [UI] 13-31) versus 8 (90% UI 6-18), and for postherpetic neuralgia, NNV was 64 (90% UI 33-93) versus 31 (90% UI 23-73). For the recombinant vaccine, the median cost-effectiveness ratios varied between cost-saving and $25 881 per QALY gained for adults aged 50 years or older. For the live vaccine, the cost-effectiveness ratios varied between cost-saving and $130 587 per QALY gained and were less than $45 000 per QALY gained only for those 65 to 75 years old. Given its higher efficacy, we estimated that the cost for the complete series of the recombinant vaccine could be $150 to $200 more than the cost of the live vaccine and still be considered cost-effective.

INTERPRETATION

Our model predicted that the recombinant subunit zoster vaccine is likely cost-effective in Canada for adults 60 years or older, and is likely more cost-effective than live attenuated zoster vaccine. These results have informed updated national and provincial recommendations on herpes zoster vaccination.

Impact of Out-of-Pocket Cost on Herpes Zoster Vaccine Uptake: An Observational Study in a Medicare Managed Care Population

Herpes zoster (HZ) vaccination is approved for adults aged 50+ for the prevention of HZ, but it is underutilized. The objective of this study was to evaluate the association between out-of-pocket cost and HZ vaccine utilization. Adults aged 65 or older enrolled for at least 12 months in Medicare Advantage/Part D (MAPD) and Medicare Part D only (PDP) plans from 1 January 2007 to 30 June 2014 were selected. Abandonment was defined as a reversed claim for HZ vaccine with no other paid claim within 90 days. Out-of-pocket costs used were actual amounts recorded in the claim. Overall, the HZ vaccine abandonment rate was 7.3%. Mean out-of-pocket costs were higher for individuals who abandoned versus those who did not ($88 (±$55) versus $80 (± $49)). Logistic regression indicated individuals with out-of-pocket costs of $80⁻$90 were 21% more likely (OR = 1.21, 1.16⁻1.27 95% CI), and those with out-of-pocket costs >$90 were 90% more likely (OR = 1.90, 1.85⁻1.96 95% CI) to abandon than those with out-of-pocket costs <$80. The models also suggested that socioeconomic, racial, and ethnic disparities in vaccine abandonment existed. Different vaccine targeting efforts and pharmacy benefit design strategies may be needed to increase use, improve adherence, and minimize disparities.

[Immunizing is not only a children's matter! : Why vaccinations are also important for adults]

Vaccinations belong to the ten most effective public health achievements worldwide. While immunization programms for children are installed in Europe, vaccinations for adults are not established. However, adult vaccination is extremely meaningful: increasing age means a higher susceptibility to infectious diseases, health problems and multimorbidity will increase. The burden of vaccine-preventable diseases is still high in Europe. Due to immunosenescence (older) adults are less protected against pathogens, antibody titers after vaccinations are lower and immunity lasts shorter. There is striking lack of data of adult vaccination rates and an international consensus regarding adult vaccination recommendations or guidelines are not available in Europe. In only six countries a comprehensive document describing recommended vaccinations for adults is available, among them Austria. The awareness of the importance of adult vaccination over the whole lifetime is not present to the necessary extent in Europe and has to be promoted.

Relationship between cell-mediated immunity to Varicella-Zoster virus and aging in subjects from the community-based Shozu Herpes Zoster study

Age-related declines in cell-mediated immunity (CMI) are associated with the incidence and severity of Herpes Zoster (HZ) infection. However, the level of Varicella-Zoster virus (VZV)-specific CMI associated with disease onset is unclear. This study aimed to examine factors associated with VZV-specific CMI, as measured by an interferon-gamma (IFN-γ) enzyme-linked immunospot (ELISPOT) assay, in a Japanese cohort. The study enrolled 365 subjects aged 60 years and over, all of whom were taking part in the Shozu Herpes Zoster (SHEZ) study and had undergone four sets of blood and intradermal reaction tests during a 3 year follow-up period. The VZV-specific immunity profile of each subject was assessed, and linear mixed effects models were constructed to analyze IFN-γ ELISPOT results in association with a combination of factors. The model that best explained the IFN-γ ELISPOT results was selected using the Akaike Information Criteria. The best-fit model consisted of age group as the only explanatory fixed-effect variable. The model showed that VZV-specific CMI, quantified as numbers of spots on the ELISPOT assay, among subjects aged 70-79 was on average 10.30 points lower than that among subjects aged 60-69. There was no statistically significant difference between subjects aged 70-79 and those aged 80-89. Age was the only factor significantly associated with the level of VZV-specific CMI, as measured by the IFN-γ ELISPOT assay. These results may represent an important step towards quantifying the relationship between VZV-specific CMI and the onset of HZ. J. Med. Virol. 89:313-317, 2017. © 2016 Wiley Periodicals, Inc.

Herpes zoster vaccine effectiveness and manifestations of herpes zoster and associated pain by vaccination status

Options for managing herpes zoster (HZ)-related pain and complications have limited effectiveness, making HZ prevention through vaccination an important strategy. Limited data are available on HZ vaccine effectiveness against confirmed HZ and manifestations of HZ among vaccinated persons. We conducted a matched case-control study to assess HZ vaccine effectiveness for prevention of HZ and other HZ-related outcomes and a cohort study of persons with HZ to compare HZ-related outcomes by vaccination status. Cases were identified through active surveillance among persons age ≥ 60 years with HZ onset and health-care encounters during 2010-2011 in Southeastern Minnesota. Controls were age- and sex-matched to cases. Data were collected by medical record review and from participants via interviews and daily pain diaries. 266 HZ case-patients and 362 matched controls were enrolled in the vaccine effectiveness studies and 303 case-patients in the cohort study of HZ characteristics by vaccination status. Vaccination was associated with 54% (95% CI:32%-69%) reduction in HZ incidence, 58% (95% CI:31%-75%) reduction in HZ prodromal symptoms, and 70% (95% CI:33%-87%) reduction in medically-attended prodrome. HZ vaccine was statistically significant effective at preventing postherpetic neuralgia (PHN) measured at 30 d after rash onset, 61% (95% CI: 22%-80%). Among persons who developed HZ, no differences were found by vaccination status in severity or duration of HZ pain after rash onset. In this population-based study, HZ vaccination was associated with >50% reduction in HZ, HZ prodrome, and medically-attended prodrome.

Herpes zoster epidemiology, management, and disease and economic burden in Europe: a multidisciplinary perspective

Herpes zoster (HZ) is primarily a disease of nerve tissue but the acute and longer-term manifestations require multidisciplinary knowledge and involvement in their management. Complications may be dermatological (e.g. secondary bacterial infection), neurological (e.g. long-term pain, segmental paresis, stroke), ophthalmological (e.g. keratitis, iridocyclitis, secondary glaucoma) or visceral (e.g. pneumonia, hepatitis). The age-related increased incidence of HZ and its complications is thought to be a result of the decline in cell-mediated immunity (immunosenescence), higher incidence of comorbidities with age and social-environmental changes. Individuals who are immunocompromised as a result of disease or therapy are also at increased risk, independent of age. HZ and its complications (particularly postherpetic neuralgia) create a significant burden for the patient, carers, healthcare systems and employers. Prevention and treatment of HZ complications remain a therapeutic challenge despite recent advances. This is an overview of the multidisciplinary implications and management of HZ in which the potential contribution of vaccination to reducing the incidence HZ and its complications are also discussed.

Herpes zoster and postherpetic neuralgia in Catalonia (Spain)

The objective of the study was to analyze the descriptive epidemiology and costs of herpes zoster (HZ) and postherpetic neuralgia (PHN) in people aged ≥50 years in Catalonia (Spain). The incidence of HZ in Catalonia was estimated by extrapolating the incidence data from Navarre (Spain) to the population of Catalonia. The incidence of PHN was estimated according to the proportion of cases of HZ in the case series of the Hospital del Sagrado Corazón de Barcelona that evolved to PHN. Drug costs were obtained directly from the prescriptions included in the medical record (according to official prices published by the General Council of the College of Pharmacists). The cost of care was obtained by applying the tariffs of the Catalan Health Institute to the number of outpatient visits and the number and duration of hospital admissions. The estimated annual incidence of HZ was 31 763, of which 21 532 (67.79%) were in patients aged ≥50 years. The respective figures for PHN were 3194 and 3085 (96.59) per annum, respectively. The mean cost per patient was markedly higher in cases of PHN (916.66 euros per patient) than in cases of HZ alone (301.52 euros per patient). The cost increased with age in both groups of patients. The estimated total annual cost of HZ and its complications in Catalonia was € 9.31 million, of which 6.54 corresponded to HZ and 2.77 to PHN. This is the first Spanish study of the disease burden of HZ in which epidemiological data and costs were collected directly from medical records. The estimated incidence of HZ is probably similar to the real incidence. In contrast, the incidence of PHN may be an underestimate, as around 25% of patients in Catalonia attend private clinics financed by insurance companies. It is also probable that the costs may be an underestimate as the costs derived from the prodromal phase were not included. In Catalonia, HZ and PHN cause an important disease burden (21 532 cases of HZ and 3085 de PHN with an annual cost of € 9.31 million) in people aged ≥50 years, in whom vaccination is indicated.

Sociodemographic characteristics and chronic medical conditions as risk factors for herpes zoster: a population-based study from primary care in Madrid (Spain)

The objectives of this study were to estimate incidence density rates (IDR) of herpes zoster (HZ) and to analyze the association with sociodemographic characteristics and selected chronic medical conditions. The study cohort consisted of the adult population included in the Public Health System of the Autonomous Community of Madrid, Spain on 1/10/2009 (5 244 402 persons). Data source were electronic medical records from primary care between 1/10/2009-31/12/2012. Individual socioeconomic status (SES) was inferred by geocoding. Poisson regression analyses were stratified by sex, to identify factors associated with HZ. We identified 81 541 incident cases of HZ (61.7% in women and 46.5% in the group aged 60 and over). IDR was 4.11 per 1000 person-years in men and 5.95 in women. IDR were higher with age, in autochthonous population, those with lower SES and in patients with immunodeficiencies. After adjustment, higher incidence rate ratios were found with age, autochthonous origin, lower SES, and in patients with HIV-infection/AIDS (3.20, CI95% 2.90-3.53 in men and 2.98, CI95% 2.58-3.45 in women), and other immunodeficiencies (1.57, CI95% 1.41-1.75 and 1.65, CI95% 1.50-1.80). COPD, asthma, DM, ischemic heart disease, other cardiovascular diseases, and cancer were also associated with an increased incidence of HZ. We conclude that older, autochthonous patients with lower SES and with certain underlying medical conditions had a higher probability of suffering HZ. Electronic databases are useful for estimating the incidence of HZ, and for finding associations with sociodemographic and clinical characteristics. Identifying unrecognized risk factors for HZ, such as asthma or cardiovascular diseases, is crucial to interpret the epidemiology of HZ, to target vaccination programs and to monitor their effect.

Practical considerations in the pharmacological treatment of postherpetic neuralgia for the primary care provider

An estimated one million individuals in the US are diagnosed with herpes zoster (HZ; shingles) each year. Approximately 20% of these patients will develop postherpetic neuralgia (PHN), a complex HZ complication characterized by neuropathic pain isolated to the dermatome that was affected by the HZ virus. PHN is debilitating, altering physical function and quality of life, and commonly affects vulnerable populations, including the elderly and the immunocompromised. Despite the availability of an immunization for HZ prevention and several approved HZ treatments, the incidence of PHN is increasing. Furthermore, management of the neuropathic pain associated with PHN is often suboptimal, and the use of available therapeutics may be complicated by adverse effects and complex, burdensome treatment regimens, as well as by patients’ comorbidities and polypharmacy, which may lead to drug–drug interactions. Informed and comprehensive assessments of currently available pharmacological treatment options to achieve effective pain control in the primary care setting are needed. In this article, we discuss the situation in clinical practice, review currently recommended prevention and treatment options for PHN, and outline practical considerations for the management of this neuropathic pain syndrome, with a focus on optimal, individual-based treatment plans for use in the primary care setting.

Cost-effectiveness of vaccination against herpes zoster

Herpes zoster (HZ) is a common disease among elderly, which may develop into a severe pain syndrome labeled postherpetic neuralgia (PHN). A live-attenuated varicella zoster virus vaccine has been shown to be effective in reducing the incidence and burden of illness of HZ and PHN, providing the opportunity to prevent significant health-related and financial consequences of HZ. In this review, we summarize the available literature on cost-effectiveness of HZ vaccination and discuss critical parameters for cost-effectiveness results. A search in PubMed and EMBASE was performed to identify full cost-effectiveness studies published before April 2013. Fourteen cost-effectiveness studies were included, all performed in western countries. All studies evaluated cost-effectiveness among elderly above 50 years and used costs per quality-adjusted life year (QALY) gained as primary outcome. The vast majority of studies showed vaccination of 60- to 75-year-old individuals to be cost-effective, when duration of vaccine efficacy was longer than 10 years. Duration of vaccine efficacy, vaccine price, HZ incidence, HZ incidence and discount rates were influential to the incremental cost-effectiveness ratio (ICER). HZ vaccination may be a worthwhile intervention from a cost-effectiveness point of view. More extensive reporting on methodology and more detailed results of sensitivity analyses would be desirable to address uncertainty and to guarantee optimal comparability between studies, for example regarding model structure, discounting, vaccine characteristics and loss of quality of life due to HZ and PHN.

Herpes zoster surveillance using electronic databases in the Valencian Community (Spain)

BACKGROUND

Epidemiologic data of Herpes Zoster (HZ) disease in Spain are scarce. The objective of this study was to assess the epidemiology of HZ in the Valencian Community (Spain), using outpatient and hospital electronic health databases.

METHODS

Data from 2007 to 2010 was collected from computerized health databases of a population of around 5 million inhabitants. Diagnoses were recorded by physicians using the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM). A sample of medical records under different criteria was reviewed by a general practitioner, to assess the reliability of codification.

RESULTS

The average annual incidence of HZ was 4.60 per 1000 persons-year (PY) for all ages (95% CI: 4.57-4.63), is more frequent in women [5.32/1000PY (95% CI: 5.28-5.37)] and is strongly age-related, with a peak incidence at 70-79 years. A total of 7.16/1000 cases of HZ required hospitalization.

CONCLUSIONS

Electronic health database used in the Valencian Community is a reliable electronic surveillance tool for HZ disease and will be useful to define trends in disease burden before and after HZ vaccine introduction.