Hospital-based herpes zoster diagnoses in Denmark: rate, patient characteristics, and all-cause mortality

A systematic review and meta-analysis of herpes zoster risk in adults with immunocompromised conditions and autoimmune diseases in Asia-Pacific

Asia-Pacific (APAC) faces an increasing burden of herpes zoster (HZ) over time. The risk of HZ and its complications are increased in immunocompromised (IC) patients and those with autoimmune diseases (AID). Our study aimed to synthesize evidence on the epidemiological burden of HZ and its complications among the general adult population and patients with IC/AID conditions in APAC. Following a systematic literature review, we performed meta-analyses for outcomes where ≥3 studies met the inclusion criteria. Of the 271 articles identified, 75 were included for meta-analysis. We found a high burden of HZ and its complications (i.e., postherpetic neuralgia, HZ ophthalmicus), particularly among individuals with IC/AID conditions in APAC. Patients with IC/AID conditions had significantly increased HZ risk and a higher proportion of HZ recurrence than the general adult population. These findings may inform clinical practice and public health decisions regarding HZ prevention, including HZ vaccination strategies, among the IC/AID population in APAC.

The effect of recombinant zoster vaccine on patients with chronic obstructive pulmonary diseases: A multi-institutional propensity score-matched cohort study

Although the recombinant zoster vaccine (RZV) has demonstrated efficacy in reducing the risk of herpes zoster (HZ) for individuals aged 50 years and older, its effectiveness in patients with chronic obstructive pulmonary disease (COPD) remains uncertain. This study was conducted to assess the effect of RZV on the risk of HZ in COPD patients. A multi-institutional propensity score-matched retrospective cohort study was conducted using the TriNetX Research network, including individuals aged 40 years or older with COPD from January 1, 2018, to December 31, 2022. Patients with a history of HZ or prior zoster vaccination were excluded. The primary outcome was HZ occurrence, with secondary outcomes including severe and nonsevere HZ. After propensity score matching, each 17 431 patients receiving RZV and unvaccinated patients were included. The vaccinated group had a significantly lower risk of HZ compared to the unvaccinated group (HR, 0.62; [95% confidence intervals] 95% CI, 0.51-0.75, p < 0.01). Similar risk reductions were observed for nonsevere HZ (HR, 0.61; 95% CI, 049-0.75, p < 0.01) and severe HZ (HR, 0.53; 95% CI, 0.38-0.73, p < 0.01). Further subgroup analyses demonstrated consistent risk reductions across age (50-59, 60-69, 70-79, and ≥80 years), sex, and comorbidities, except for individual aged 40-49 years. This study confirms the effectiveness of RZV in reducing HZ risk in patients with COPD aged 50 years and older, supporting its administration in this population. However, vaccination rates remain low, highlighting the need for improved vaccination strategies in this high-risk group. Efforts to enhance vaccine uptake are warranted to reduce HZ morbidity.

The Incidence of Herpes Zoster Complications: A Systematic Literature Review

INTRODUCTION

The objective of this work was to summarize the incidence of herpes zoster (HZ) complications in different populations.

METHODS

Systematic literature review of PubMed, Embase, and Virtual Health Library records between January 1, 2002 and October 20, 2022 using search strings for HZ, complications, and frequency measurements.

RESULTS

The review included 124 studies, most conducted in the general population (n = 93) and on individuals with comorbidities (n = 41) ≥ 18 years of age. Most studies were conducted in Europe (n = 44), Asia (n = 40), and North America (n = 36). Postherpetic neuralgia (PHN) was the most studied neurological complication. Variable relative PHN incidence was found in the general population (2.6-46.7%) or based on diagnosis: immunocompromised (3.9-33.8%), depression (0-50%), and human immunodeficiency virus (HIV) (6.1-40.2%). High incidence rates were observed in hematological malignancies (HM) and solid organ malignancies (132.5 and 93.7 per 1000 person-years, respectively). Ocular complications were frequently reported with herpes zoster ophthalmicus (HZO). The relative incidence (incidence rate) of HZO in the general population was reported as 1.4-15.9% (0.31-0.35 per 1000 person-years). High relative incidence was observed in HIV (up to 10.1%) and HM (3.2-11.3%). Disseminated HZ was the most frequently reported cutaneous complication. The relative incidence of disseminated HZ was 0.3-8.2% in the general population, 0-0.5% in the immunocompetent, and 0-20.6% in patients with comorbidities. High relative incidence was reported in HM and solid organ transplant (up to 19.3% and 14.8%, respectively).

DISCUSSION

Most reported complications were neurological (n = 110), ocular (n = 48), and cutaneous (n = 38). Few studies stratified complications by age or gender (or both). Incidence appeared higher in select immunocompromised populations. Higher incidence was associated with older age in several studies; the general association with gender was unclear.

CONCLUSIONS

Variable incidence of HZ complications was reported by population subgroup. Further research is required to quantitatively analyze incidence by age, gender, and location.

Herpes Zoster Ophthalmicus: Presentation, Complications, Treatment, and Prevention

Herpes zoster (HZ) is caused by reactivation of latent infection of varicella zoster virus (VZV) in sensory (cranial, dorsal root) ganglia. Major risk factors for HZ are increasing age and immunosuppression. HZ ophthalmicus (HZO) is a subset of HZ with involvement of the ophthalmic division of the fifth cranial trigeminal nerve. Approximately 4-20% of patients with HZ develop HZO. Approximately 50% of patients with HZO develop ocular disease, among whom up to 25% develop chronic or recurrent disease. Common manifestations of ocular disease include conjunctivitis, keratitis, and uveitis, whereas optic neuropathy and retinitis are uncommon. Due to the potential for vision impairment, ocular involvement requires urgent ophthalmic consultation. Early recognition and timely treatment with antivirals may prevent ocular complications. HZO is preventable by vaccination against HZ. Vaccine efficacy/effectiveness studies have been largely conducted for HZ with few studies assessing HZO. Both the recombinant adjuvanted vaccine (RZV) and live-attenuated vaccine (ZVL) significantly reduce the incidence of HZ and HZO in older adults. RZV is more effective than ZVL. Data on the effectiveness of vaccines for prevention of recurrent disease in patients with HZO are limited; however, vaccination is recommended. Despite recommendations to vaccinate individuals likely to benefit from an HZ vaccine, coverage for adults remains suboptimal. Barriers to vaccination include patient beliefs about HZ or HZ vaccines, and factors related to healthcare providers. In particular, the lack of a recommendation from their primary care physician is often cited by patients as a reason for remaining unvaccinated. By encouraging vaccination against HZ, physicians not only prevent HZ and HZO but also potential vision loss due to HZO.Graphical abstract available for this article.

The Burden of Herpes Zoster on Hospital Admissions: A Retrospective Analysis in the Years of 2015-2021 from the Abruzzo Region, Italy

(1) Background: Herpes zoster (HZ) is a disease caused by the reactivation of the Varicella Zoster Virus (VZV). Clinical reactivation, herpes zoster, takes place in 10-20% of subjects who contracted the primary infection, with a higher risk of developing zoster increasing proportionally with age, especially after 50 years of age. HZ is a common clinical problem, particularly among patients aged over 50 years and immunocompromised patients. Immunocompromised patients and adults could present an atypical and more severe course. In addition, they are at greater risk of complications. For this reason, it is important to understand the real burden of the disease and to identify the subjects who are at higher risk of HZ and its complications, also to direct preventive strategies at the right targets. The aim of the present study is to analyze HZ-related hospitalization trends in Abruzzo in the period of 2015-2021. (2) Methods: Data related to hospital admissions were extracted from the hospital discharge records (HDRs) of the whole region, considering all admissions during the years of 2015-2021. The trends in hospital admissions and length of stay were evaluated and analyzed. (3) Results: A total of 768 hospital discharges with a diagnosis of herpes zoster were registered in Abruzzo during the 7-year study period. During the study period, an increasing trend was observed from the year 2015 to the year 2017, ranging from 8.19 cases/100,000 to 11.5 cases/100,000 (APC (Annual percentage change) +20.8%; 95%CI -2.3; 47.6). After the year 2017, a significantly decreasing trend was observed, reaching 5.46 cases/100,000 in the year 2021 (APC -18.4%; 95%CI -31.5; -12.0). Across the entire study period, an average annual percentage change (AAPC) of -7.0% (95%CI -13.0; -1.3) was observed. (4) Conclusions: Despite the trend of a reduction in hospitalizations, this study highlights that HZ continues to have a great impact on public health. So, it is important to update recommendations for the use of the already available HZ vaccine and to implement new strategies to increase awareness of the prevention of the disease.

Hospitalizations of patients with herpes zoster in Poland during 2012-2021: A population-based study

INTRODUCTION

The varicella-zoster virus (VZV) is an infectious agent that causes both chickenpox and herpes zoster/shingles (HZ). This infection can take various clinical forms, result in permanent complications, and be a marker of immunosuppression, e.g. in the course of a neoplastic disease. The aim of this study is to analyze epidemiological trends in hospitalization and hospital mortality rate among HZ patients in Poland (2012-2021).

METHODS

Our study is a population-based, retrospective analysis of hospital discharge records of patients with HZ. Data were obtained from the National Institute of Public Health in Poland, and they covered the period from 2012 to 2021. All hospitalization records with primary or secondary ICD-10 B02 code diagnosis were included in the study.

RESULTS

We analyzed the total number of 23,432 hospital discharge records of HZ patients in 2012-2021. The study group consisted of 22,169 (94.6 %) hospitalization records of first-time diagnosis of HZ in hospitalized patients: 9,309 males (42 %) and 12,860 females (58 %). In this group, 70.3 % were patients over 60 years old. The mean and median age was 64 and 69 years, respectively. The mean annual first-time hospitalization rate for HZ was estimated to be 5.8 per 100,000 person-years (95 % CI: 4.8-6.7 per 100,000 person-years). The hospitalization rate for HZ was similar during 2012-2019. There was a significant decrease in hospitalizations in 2020-2021 in comparison with the previous years (R2 = 0.42, p < 0.05). Women showed a higher hospitalization rate than men (p < 0.001). Urban residents had a higher hospitalization rate than rural residents (p < 0.001). In the analyzed period, 246 deaths were recorded (1.1 % of all hospitalized HZ patients) -119 males and 127 females.

CONCLUSIONS

The HZ-related number of hospitalizations and mortality in Poland are relatively low, but HZ is still a significant health problem. Risk factors include female gender, older age and residence in urban areas.

Decline in hospitalization rates for herpes zoster in Italy (2003-2018): reduction in the burden of disease or changing of hospitalization criteria?

BACKGROUND

Herpes Zoster (HZ) is a very demanding disease caused by the reactivation of latent Varicella Zoster Virus. The main aim of this study was to estimate the burden of the HZ hospitalizations in Italy from 2003 to 2018 evaluating temporal trends.

METHODS

Retrospective population-based study analyzing Hospital Discharge Records. Hospitalization records reporting the ICD-9 CM 053.X code in the principal diagnosis or in any of the five secondary diagnoses were considered as cases. Trends of hospitalization rates have been evaluated by Joinpoint analyses.

RESULTS

Overall, 99,036 patients were hospitalized with HZ in the 16-year period of the study, and 83,720 (84.5%) of these patients were over 50 years. Hospitalization rate was 10.4 per 100,000 persons/year with a significant decreasing trend from 13.9 in 2003-2006 to 7.8 in 2015-2018 (p < 0.001). Hospitalization rates showed a 20-fold higher risk among subjects aged over 80 years and 11-fold higher risk among 70-79-year-old subjects with respect to those aged less than 50 years. Over time, a statistically significant increase was observed for the case fatality rate (from 1.2 to 1.7%; p < 0.001) and the median length of stay (from 7 to 8 days; p < 0.001).

CONCLUSIONS

Zoster is a disease that causes hospitalization as relatively frequent complication and the observed reduced trend over time could be due to a restriction in hospitalization criteria instead of a reduced burden of disease. The decreasing trend should be carefully interpreted, since it could have an impact on promoting herpes zoster vaccination.

Incidence of acute complications of herpes zoster among immunocompetent adults in England: a matched cohort study using routine health data

BACKGROUND

Herpes zoster can cause rare but serious complications; the frequency of these complications has not been well described.

OBJECTIVES

To quantify the risks of acute non-postherpetic neuralgia (PHN) zoster complications, to inform vaccination policy.

METHODS

We conducted a cohort study among unvaccinated immunocompetent adults with incident zoster, and age-, sex- and practice-matched control adults without zoster, using routinely collected health data from the UK Clinical Practice Research Datalink (years 2001 to 2018). Crude attributable risks of complications were estimated as the difference between Kaplan-Meier-estimated 3-month cumulative incidences in patients with zoster vs. controls. We used Cox models to obtain hazard ratios for our primary outcomes in patients with and without zoster. Primary outcomes were ocular, neurological, cutaneous, visceral and zoster-specific complications. We also assessed whether antivirals during acute zoster protected against the complications.

RESULTS

In total 178 964 incident cases of zoster and 1 799 380 controls were included. The absolute risks of zoster-specific complications within 3 months of zoster diagnosis were 0·37% [95% confidence interval (CI) 0·34-0·39] for Ramsay Hunt syndrome, 0·01% (95% CI 0·0-0·01) for disseminated zoster, 0·04% (95% CI 0·03-0·05) for zoster death and 0·97% (95% CI 0·92-1·00) for zoster hospitalization. For other complications, attributable risks were 0·48% (95% CI 0·44-0·51) for neurological complications, 1·33% (95% CI 1·28-1·39) for ocular complications, 0·29% (95% CI 0·26-0·32) for cutaneous complications and 0·78% (95% CI 0·73-0·84) for visceral complications. Attributable risks were higher among patients > 50 years old. Patients with zoster had raised risks of all primary outcomes relative to controls. Antiviral prescription was associated with reduced risk of neurological complications (hazard ratio 0·61, 95% CI 0·53-0·70).

CONCLUSIONS

Non-PHN complications of zoster were relatively common, which may affect cost-effectiveness calculations for zoster vaccination. Clinicians should be aware that zoster can lead to various complications, besides PHN.

Herpes Zoster in Solid Organ Transplantation: Incidence and Risk Factors

Background

Studies on herpes zoster (HZ) incidence in solid organ transplant (SOT) recipients report widely varying numbers. We investigated HZ incidence, severity, and risk factors in recipients of four different SOTs, with a follow-up time of 6-14 years.

Methods

Records of 1,033 transplant recipients after first heart (HTx: n = 211), lung (LuTx: n = 121), liver (LiTx: n = 258) and kidney (KTx: n = 443) transplantation between 2000 and 2014 were analyzed for VZV-PCR, clinical signs of HZ, and complications.

Results

HZ was diagnosed in 108 of 1,033 patients (10.5%): 36 HTx, 17 LuTx, 15 LiTx, and 40 KTx recipients. Overall HZ incidence rate after HTx (30.7 cases/1,000 person-years (PY)), LuTx (38.8 cases/1,000 PY), LiTx (22.7 cases/1,000 PY) and KTx (14.5 cases/1,000 PY) was significantly higher than in the general 50-70 year population. Multivariable analysis demonstrated age ≥50 years at transplantation (p = 0.038, RR 1.536), type of organ transplant (overall p = 0.002; LuTx p = 0.393; RR 1.314; LiTx p = 0.011, RR 0.444; KTx p = 0.034, RR 0.575), CMV prophylaxis (p = 0.043, RR 0.631) and type of anti-rejection therapy (overall p = 0.020; methylprednisolone p = 0.008, RR 0.475; r-ATG p = 0.64, RR1.194) as significant risk factors. Complications occurred in 33 of 108 (31%) patients (39% of HTx, 47% of LuTx, 20% of LiTx, 20% of KTx): post-herpetic neuralgia, disseminated disease, and cranial nerve involvement.

Conclusion

HZ incidence and severity in SOT recipients are most pronounced after heart and lung transplantation, in older patients, and when CMV prophylaxis is lacking.

Incidence of Hospitalizations and Emergency Department Visits for Herpes Zoster in Immunocompromised and Immunocompetent Adults in Ontario, Canada, 2002-2016

BACKGROUND

Immunocompromised adults are at .increased risk of herpes zoster (HZ) infection and related complications. We aimed to assess the incidence of hospital-attended HZ (ie, seen in hospital or emergency department) in immunocompromised populations and compare it to immunocompetent populations.

METHODS

We calculated incidence rates (IRs) of hospital-attended HZ in Ontario, Canada, between 1 April 2002 and 31 August 2016 in adults ≥18 years of age categorized as immunocompromised or immunocompetent. We repeated these analyses by type of immunocompromising condition and provided incidence rate ratios (IRRs) comparing to immunocompetent adults. We also calculated IRs and IRRs of HZ complications by immunocompromised status.

RESULTS

There were 135 206 incident cases of hospital-attended HZ during the study period. Immunocompromised adults accounted for 13% of these cases despite representing 3% of the population. The risk of hospital-attended HZ was higher for immunocompromised adults compared with immunocompetent adults (IRR, 2.9 [95% confidence interval {CI}, 2.9-3.0]) and ranged across type of immunocompromising conditions, from 2.6 (95% CI, 2.6-2.7) in those with a solid tumor malignancy to 12.3 (95% CI, 11.3-13.2) in those who had undergone hematopoietic stem cell transplant. The risk of any HZ complication was higher in immunocompromised adults (IRR, 3.6 [95% CI, 3.5-3.7]) and highest for disseminated zoster (IRR, 32.8 [95% CI, 27.8-38.6]).

CONCLUSIONS

The risk of hospital-attended HZ and related complications was higher in immunocompromised populations compared with immunocompetent populations. Our findings underscore the high-risk nature of this population and the potential benefits that may be realized through HZ vaccination.

Herpes zoster in older adults in Ontario, 2002-2016: Investigating incidence and exploring equity

Older adults are at increased risk of herpes zoster (HZ) and post-herpetic neuralgia (PHN) and HZ vaccines are available to help prevent infection. The objective of our study was to provide updated data on incidence of HZ and PHN related to clinical and demographic factors in older adults to inform immunization practices. We conducted a population-based, retrospective cohort study and included all cases of HZ seen in outpatient, emergency department, and hospital settings for adults aged 65 years and over between April 1, 2002 to August 31, 2016 in Ontario, Canada. We calculated the incidence of HZ and PHN, and estimated the proportion within each subgroup that developed PHN. We also assessed incidence by neighbourhood-level income quintile before and after the availability of vaccine for private purchase. The average annual incidence of HZ in any setting was 59.0 per 10,000 older adults, with higher incidence in outpatient as opposed to hospital settings. Incidence was higher in the oldest age groups, females, and those classified as immunocompromised or frail. Relative to the pre-vaccine era, the disparities in incidence of HZ by neighbourhood-level income increased, with higher rates of HZ and PHN seen in those residing in lower income quintiles. Additional prevention efforts should be targeted toward adults who are immunocompromised, frail, and those living in lower socioeconomic quintiles. Future work should assess the impact of the zoster vaccine program with a particular focus on equity in the publicly-funded era.

Radiation therapy and the risk of herpes zoster in patients with cancer

BACKGROUND

The role and impact of radiation therapy (RT) on the development of herpes zoster (HZ) has not been well studied. The objective of this study was to investigate the association between RT and HZ.

METHODS

A propensity score-matched, retrospective cohort study was conducted using institutional cancer registry data and medical records from 2011 to 2015. The risk of developing HZ in the RT and non-RT groups was compared using a Cox proportional hazards model. Associations also were explored between the RT field and the anatomic location of HZ in patients who developed HZ after RT. The expected number of HZ events within the radiation field was calculated according to the RT received by each patient; then, this number was compared with the observed number of in-field events.

RESULTS

Of 17,655 patients, propensity score matching yielded 4350 pairs; of these, 3891 pairs were eligible for comparison. The cumulative incidence of HZ in the RT group (vs the non-RT group) during the first 5 years after the index date was 2.1% (vs 0.7%) at 1 year, 3.0% (vs 1.0%) at 2 years, 3.4% (vs 1.3%) at 3 years, 4.1% vs 1.7% at 4 years, and 4.4% vs 1.8% at 5 years. The RT group showed a significantly higher risk of HZ than the non-RT group (hazard ratio, 2.59, 95% CI, 1.84-3.66). In the 120 patients who developed HZ after RT, HZ events were observed significantly more frequently within the RT field than expected (74 vs 43.8 events; P < .001).

CONCLUSIONS

Patients with cancer who received RT showed a significantly higher risk of HZ, which was commonly observed within the radiation field.

The burden of herpes zoster disease in Norway

BACKGROUND

No national vaccination program against herpes zoster (HZ) is currently in place in Norway. We aimed to quantify the burden of medically attended HZ to assess the need for a vaccination program.

METHODS

We linked data from several health registries to identify medically attended HZ cases during 2008-2014 and HZ-associated deaths during1996-2012 in the entire population of Norway. We calculated HZ incidences for primary and hospital care by age, sex, type of health encounter, vaccination status, and co-morbidities among hospital patients. We also estimated HZ-associated mortality and case-fatality.

RESULTS

The study included 82,064 HZ patients, of whom none were reported as vaccinated against HZ. The crude annual incidence of HZ was 227.1 cases per 100,000 in primary healthcare and 24.8 cases per 100,000 in hospitals. Incidence rates were higher in adults aged ≥50 years (461 per 100,000 in primary care and 57 per 100,000 in hospitals), and women than in men both in primary healthcare (267 vs 188 per 100,000), and hospitals (28 vs 22 per 100,000). Among hospital patients, 47% had complicated zoster and 25% had comorbidities, according to the Charlson comorbidity index. The duration of hospital stay (median 4 days) increased with the severity of comorbidities. The estimated mortality rate was 0.18 per 100,000; and in-hospital case-fatality rate was 1.04%.

CONCLUSIONS

Medically attended HZ poses a substantial burden in the Norwegian healthcare sector. The majority of the zoster cases occurred among adults aged ≥50 years - the group eligible for zoster vaccination - and increased use of zoster vaccination may be warranted, especially among persons with co-morbidities.

Burden of herpes zoster in 16 selected immunocompromised populations in England: a cohort study in the Clinical Practice Research Datalink 2000-2012

OBJECTIVES

Herpes zoster (HZ) is caused by reactivation of varicella-zoster virus which remains latent in individuals after a varicella infection. It is expected that HZ will be more frequent in immunocompromised (IC) individuals than in immunocompetent (IC-free). This study assessed the incidence rate (IR) of HZ in individuals with a wide set of IC conditions and in IC-free individuals.

SETTING

A retrospective cohort study was conducted in England using data (January 2000 to March 2012) from the Clinical Practice Research Datalink with linkage to the Hospital Episodes Statistics.

PARTICIPANTS

A cohort of 621 588 individuals with 16 selected IC conditions and a gender/age-matched cohort of IC-free individuals were identified. The IC conditions included haematopoietic stem cell transplant (HSCT), solid organ transplant, malignancies, autoimmune diseases and users of immunosuppressive medications.

OUTCOMES

IR of HZ per 1000 person-years (PY) was estimated. Proportions of postherpetic neuralgia (PHN) and other HZ complications within 90 days of HZ onset were also estimated among patients with HZ. Risk factors for PHN in IC individuals with HZ were assessed by a multivariate regression model.

RESULTS

The overall IR of HZ in the IC cohort was 7.8/1000 PY (95% CI 7.7 to 7.9), increasing with age from 3.5/1000 PY (3.4-3.7) in individuals aged 18-49 years to 12.6/1000 PY (12.2-13.0) in individuals aged ≥80 years. This IR in the IC-free cohort was 6.2/1000 PY (6.1-6.3). The overall IR of HZ varied across IC conditions, ranging from 5.3 (5.1-5.5) in psoriasis to 41.7/1000 PY (35.7-48.4) in HSCT. The proportions of PHN and other HZ complications were 10.7% (10.2-11.1) and 2.9% (2.7-3.2) in the IC cohort, but 9.1% (8.7-9.5) and 2.3% (2.1-2.6) in the IC-free cohort, respectively.

CONCLUSION

IC population contributes to the public health burden of HZ in England. Vaccination might be the most preferable HZ preventive measure for the IC population.

Varicella-related Primary Health-care Visits, Hospitalizations and Mortality in Norway, 2008-2014

BACKGROUND

Norway does not currently implement universal varicella vaccination in childhood. We aimed to characterize health care burden of varicella in Norway in the prevaccine era.

METHODS

We linked individual patient data from different national registries to examine varicella vaccinations and varicella-coded primary care consultations, hospitalizations, outpatient hospital visits, deaths and viral infections of central nervous system in the whole population of Norway during 2008-2014. We estimated health care contact rates and described the epidemiology of medically attended varicella infection.

RESULTS

Each year approximately 14,600 varicella-related contacts occurred within primary health care and hospital sector in Norway. The annual contact rate was 221 cases per 100,000 population in primary health care and 7.3 cases per 100,000 in hospital care. Both in primary and hospital care, the highest incidences were observed among children 1 year of age: 2,654 and 78.1 cases per 100,000, respectively. The annual varicella mortality was estimated at 0.06 deaths per 100,000 and in-hospital case-fatality rate at 0.3%. Very few (0.2-0.5%) patients were vaccinated against varicella. Among hospitalized varicella patients, 22% had predisposing conditions, 9% had severe-to-very severe comorbidities and 5.5% were immunocompromised. Varicella-related complications were reported in 29.3% of hospitalized patients. Varicella zoster virus was the third most frequent virus found among 16% of patients with confirmed viral infections of central nervous system.

CONCLUSIONS

Varicella causes a considerable health care burden in Norway, especially among children. To inform the policy decision on the use of varicella vaccination, a health economic assessment of vaccination and mathematical modeling of vaccination impact are needed.

Prevaccination epidemiology of herpes zoster in Denmark: Quantification of occurrence and risk factors

BACKGROUND

Herpes zoster (HZ) is a vaccine-preventable disease caused by reactivation of the varicella-zoster virus. Unfortunately, formulation of recommendations on routine immunization is hampered by a lack of data on disease burden, since most countries do not record cases of HZ in the general population. We developed and validated an algorithm to identify HZ based on routinely collected registry data and used it to quantify HZ occurrence and risk factors in Denmark prior to marketing of the HZ vaccine.

METHODS

We included patients aged ≥40years with a first-time systemic Acyclovir, Valacyclovir, or Famciclovir prescription or a hospital-based HZ diagnosis in the Danish nationwide health registries during 1997-2013. In a validation substudy (n=176), we computed the proportion of persons with HZ among patients who redeemed antiviral prescriptions. In a cohort study, we computed age-specific rates of HZ (45,297,258 person-years). In a case-control study, we then computed odds ratios (ORs) for common chronic diseases and immunosuppressive factors among HZ cases (n=189,025) vs. matched population controls (n=945,111).

RESULTS

Medical record review confirmed HZ in 87% (95% confidence interval: 79-93%) of persons ≥40years who dispensed antivirals at doses recommended for HZ. HZ rates increased from 2.15/1000 person-years in 40-year-olds to 9.45/1000 person-years in 95-year-olds. Rates were highest in women. HZ was diagnosed during hospitalization among 3.5%. As expected, persons with severe immunosuppressive conditions had the highest ORs of HZ (between 1.82 and 4.12), but various autoimmune diseases, asthma, chronic kidney disease, and inhaled glucocorticoids were also associated with increased ORs (between 1.06 and 1.64).

CONCLUSION

This algorithm is a valid tool for identifying HZ in routine healthcare data. It shows that HZ is common in Denmark, especially in patients with certain chronic conditions. Prioritized vaccination of such high-risk patients might be an option in countries considering alternatives to universal vaccination.

Translation of the UK Pediatric Influenza Vaccination Programme in Primary Schools to 13 European Countries Using a Dynamic Transmission Model

Objectives: To simulate the impact of a pediatric influenza vaccination programme using quadrivalent live attenuated influenza vaccine (QLAIV) in Europe by applying coverage rates achieved in the United Kingdom during the 2014-2015 season and to compare the model outcomes to the UK results. Methods: We used a deterministic, age-structured, dynamic transmission model adapted to the demography, contact patterns and influenza incidence of 13 European countries, with a 10-year horizon. The reference strategy was the unchanged country-specific coverage rate, using quadrivalent inactivated vaccine (assumed efficacy against infection from 45% in 1-year-old children to 60% in healthy adults). In the evaluated strategy, 56.8% of 5-10-year-old children were additionally vaccinated with QLAIV (assumed efficacy 80%), as was the case in 2014-2015 in the United Kingdom's primary school pilot areas. Symptomatic influenza cases and associated medical resources (primary care consultations [PCC], hospitalization, intensive care unit [ICU] admissions) were calculated. The evaluated versus reference strategies were compared using odds ratios (ORs) for PCC in the target (aged 5-10-years) and non-target adult (aged >17 years) populations as well as number needed to vaccinate (NNV) with QLAIV to avert one PCC, hospitalization or ICU admission. Model outcomes, averaged over 10 seasons, were compared with published real-life data from the United Kingdom for the 2014-2015 season. Results: Over 13 countries and 10 years, the evaluated strategy prevented 32.8 million of symptomatic influenza cases (172.3 vs 205.2 million). The resulting range of ORs for PCC was 0.18-0.48 among children aged 5-10-years, and the published OR in the United Kingdom was 0.06 (95% confidence interval [0.01; 0.62]). In adults, the range of ORs for PCC was 0.60-0.91 (UK OR=0.41 [0.19; 0.86]). NNV ranges were 6-19 per averted PCC (UK NNV=16), 530-1524 per averted hospitalization (UK NNV=317) and 5298-15 241 per averted ICU admission (UK NNV=2205). Conclusions: Across a range of European countries, our model shows the beneficial direct and indirect impact of a paediatric vaccination programme using QLAIV in primary school-aged children, consistent with what was observed during a single season in the United Kingdom. Recommendations for the implementation of pediatric vaccination programmes are, therefore, supported in Europe.