The effect of vaccination on the epidemiology of varicella zoster virus

Epidemiological Characteristics of Varicella in Anhui Province, China, 2012-2021: Surveillance Study

BACKGROUND

Varicella is a mild, self-limited disease caused by varicella-zoster virus (VZV) infection. Recently, the disease burden of varicella has been gradually increasing in China; however, the epidemiological characteristics of varicella have not been reported for Anhui Province.

OBJECTIVE

The aim of this study was to analyze the epidemiology of varicella in Anhui from 2012 to 2021, which can provide a basis for the future study and formulation of varicella prevention and control policies in the province.

METHODS

Surveillance data were used to characterize the epidemiology of varicella in Anhui from 2012 to 2021 in terms of population, time, and space. Spatial autocorrelation of varicella was explored using the Moran index (Moran I). The Kulldorff space-time scan statistic was used to analyze the spatiotemporal aggregation of varicella.

RESULTS

A total of 276,115 cases of varicella were reported from 2012 to 2021 in Anhui, with an average annual incidence of 44.8 per 100,000, and the highest incidence was 81.2 per 100,000 in 2019. The male-to-female ratio of cases was approximately 1.26, which has been gradually decreasing in recent years. The population aged 5-14 years comprised the high-incidence group, although the incidence in the population 30 years and older has gradually increased. Students accounted for the majority of cases, and the proportion of cases in both home-reared children (aged 0-7 years who are not sent to nurseries, daycare centers, or school) and kindergarten children (aged 3-6 years) has changed slightly in recent years. There were two peaks of varicella incidence annually, except for 2020, and the incidence was typically higher in the winter peak than in summer. The incidence of varicella in southern Anhui was higher than that in northern Anhui. The average annual incidence at the county level ranged from 6.61 to 152.14 per 100,000, and the varicella epidemics in 2018-2021 were relatively severe. The spatial and temporal distribution of varicella in Anhui was not random, with a positive spatial autocorrelation found at the county level (Moran I=0.412). There were 11 districts or counties with high-high clusters, mainly distributed in the south of Anhui, and 3 districts or counties with high-low or low-high clusters. Space-time scan analysis identified five possible clusters of areas, and the most likely cluster was distributed in the southeastern region of Anhui.

CONCLUSIONS

This study comprehensively describes the epidemiology and changing trend of varicella in Anhui from 2012 to 2021. In the future, preventive and control measures should be strengthened for the key populations and regions of varicella.

Vaccination in children with immune-mediated disorders

OBJECTIVE

To present an updated review of recommendations for the vaccination of children with immune-mediated diseases, with an emphasis on rheumatic and inflammatory diseases.

SOURCE OF DATA

Studies published in the PubMed and Scielo databases between 2002 and 2022, Guidelines of Brazilian Scientific Societies, Manuals and Technical Notes of the Ministry of Health of Brazil, on current immunization schedules for special populations.

DATA SYNTHESIS

Immunosuppressive drugs and biological agents reduce the immunogenicity of vaccines and favor susceptibility to infections. The safety and efficacy of immunogens are important points for vaccination in children with immune-mediated diseases. The safety threshold of a vaccine applied to immunocompromised individuals can be reduced when compared to healthy individuals. Very often, the recommendations for the immunization of children with immune-mediated diseases follow the recommendations for immunocompromised patients. Vaccination against COVID-19, on the other hand, should ideally occur when the disease is stabilized and in the absence of a low degree of immunosuppression. The patients should be informed about the possibility that the immunization may fail during treatment with immunosuppressants. Specific vaccination schedules should be considered to ensure better protection.

CONCLUSIONS

Recent studies have allowed updating the recommendations on the safety and immunogenicity of vaccination in children with immune-mediated diseases, especially for live attenuated vaccines. There is a scarcity of data on the safety and efficacy of COVID-19 vaccines in patients, particularly pediatric patients, with rheumatic diseases. The completion of ongoing studies is expected to help guide recommendations on COVID-19 vaccines in this group of patients.

EULAR/PRES recommendations for vaccination of paediatric patients with autoimmune inflammatory rheumatic diseases: update 2021

OBJECTIVES

Recent insights supporting the safety of live-attenuated vaccines and novel studies on the immunogenicity of vaccinations in the era of biological disease-modifying antirheumatic drugs in paediatric patients with autoimmune/inflammatory rheumatic diseases (pedAIIRD) necessitated updating the EULAR recommendations.

METHODS

Recommendations were developed using the EULAR standard operating procedures. Two international expert committees were formed to update the vaccination recommendations for both paediatric and adult patients with AIIRD. After a systematic literature review, separate recommendations were formulated for paediatric and adult patients. For pedAIIRD, six overarching principles and seven recommendations were formulated and provided with the level of evidence, strength of recommendation and Task Force level of agreement.

RESULTS

In general, the National Immunisation Programmes (NIP) should be followed and assessed yearly by the treating specialist. If possible, vaccinations should be administered prior to immunosuppressive drugs, but necessary treatment should never be postponed. Non-live vaccines can be safely given to immunosuppressed pedAIIRD patients. Mainly, seroprotection is preserved in patients receiving vaccinations on immunosuppression, except for high-dose glucocorticoids and B-cell depleting therapies. Live-attenuated vaccines should be avoided in immunosuppressed patients. However, it is safe to administer the measles-mumps-rubella booster and varicella zoster virus vaccine to immunosuppressed patients under specific conditions. In addition to the NIP, the non-live seasonal influenza vaccination should be strongly considered for immunosuppressed pedAIIRD patients.

CONCLUSIONS

These recommendations are intended for paediatricians, paediatric rheumatologists, national immunisation agencies, general practitioners, patients and national rheumatology societies to attain safe and effective vaccination and optimal infection prevention in immunocompromised pedAIIRD patients.

Epidemiological Characteristics of Varicella under Different Immunisation Strategies in Suzhou Prefecture, Jiangsu Province

Background: The varicella vaccine is excluded from the Chinese national immunisation programme but is included in the local expanded programme on immunisation (EPI) in the Suzhou Prefecture. This study investigated the epidemiological characteristics of the varicella cases during the implementation of different immunisation strategies in the Suzhou Prefecture, Jiangsu Province. Methods: In this study, we used descriptive statistics. Information on reported instances from 2012 to 2021 was first retrieved. Data on varicella cases were collected from the China Information System for Disease Control and Prevention (CISDCP). Similarly, information on vaccinated children was obtained from the Jiangsu Province Vaccination Integrated Service Management Information System (JPVISMIS). The census data in this study was procured from the Suzhou Bureau of Statistics. Results: From 2012 to 2021, a total of 118,031 cases of varicella were reported in Suzhou, and the average annual reported incidence was 91.35 per 100,000. The average yearly incidence after implementing the two-dose varicella vaccination decreased by 41.57% compared with the implementation of one dose. This study demonstrates two annual incidence peaks, a small peak between April and July and a prominent peak between October and January. It is also possible that this seasonal distribution is related to the geography of Suzhou. The average annual reported incidence between districts with a statistically significant difference (χ2 = 98.077, p < 0.05). The one-dose varicella vaccination coverage gradually increased from 55.34% in 2012 to 89.06% in 2021 and the two-dose varicella vaccination coverage gradually increased from 0.27% in 2012 to 82.17% in 2021. Conclusions: Administering the varicella vaccine in the local EPI has significantly decreased the incidence rate and the total number of cases. A two-dose vaccination schedule is still the best vaccination strategy for varicella vaccine effectiveness.

Comparing Prodrugs with Acyclovir for Treating Postherpetic Neuralgia among Herpes Zoster Patients: A Systematic Review and Meta-Analysis

Postherpetic neuralgia (PHN) is a common, painful, and long-term complication of herpes zoster (HZ). PHN increases the demand for healthcare services and, previous studies showed that patients who received antiviral agents were less likely to develop PHN. The objective of this study was to compare the efficacy of prodrugs and acyclovir in treating PHN among patients with HZ. The search included the PubMed, Medline, Embase, and Cochrane Center of Register of Controlled Trails databases through February 2022. Clinical trials and randomized controlled trials (RCTs) involving antiviral agent intervention for HZ patients diagnosed with PHN were eligible for inclusion. A meta-analysis was conducted to calculate pooled risk ratios (RRs) with 95% confidence intervals (CIs) with a fix-effect model. Five RCTs with 1147 HZ patients met our eligibility criteria. Our meta-analysis found that there was a significantly lower risk of PHN for members of the prodrugs group (famciclovir and valaciclovir) compared with those who received acyclovir (RR = 0.86, 95%, CI: 0.75 to 0.98, p = 0.03). The review of studies indicated that the efficacy of prodrugs was better than acyclovir for reliving PHN.

Detection of Circulating VZV-Glycoprotein E-Specific Antibodies by Chemiluminescent Immunoassay (CLIA) for Varicella-Zoster Diagnosis

Varicella and herpes zoster are mild symptoms-associated diseases caused by varicella–zoster virus (VZV). They often cause severe complications (disseminated zoster), leading to death when diagnoses and treatment are delayed. However, most commercial VZV diagnostic tests have low sensitivity, and the most sensitive tests are unevenly available worldwide. Here, we developed and validated a highly sensitive VZV diagnostic kit based on the chemiluminescent immunoassay (CLIA) approach. VZV-glycoprotein E (gE) was used to develop a CLIA diagnostic approach for detecting VZV-specific IgA, IgG, and IgM. The kit was tested with 62 blood samples from 29 VZV-patients classified by standard ELISA into true-positive and equivocal groups and 453 blood samples from VZV-negative individuals. The diagnostic accuracy of the CLIA kit was evaluated by receiver-operating characteristic (ROC) analysis. The relationships of immunoglobulin-isotype levels between the two groups and with patient age ranges were analyzed. Overall, the developed CLIA-based diagnostic kit demonstrated the detection of VZV-specific immunoglobulin titers depending on sample dilution. From the ELISA-based true-positive patient samples, the diagnostic approach showed sensitivities of 95.2%, 95.2%, and 97.6% and specificities of 98.0%, 100%, and 98.9% for the detection of VZV-gE-specific IgA, IgG, and IgM, respectively. Combining IgM to IgG and IgA detection improved diagnostic accuracy. Comparative analyses on diagnosing patients with equivocal results displaying very low immunoglobulin titers revealed that the CLIA-based diagnostic approach is overall more sensitive than ELISA. In the presence of typical VZV symptoms, CLIA-based detection of high titer of IgM and low titer of IgA/IgG suggested the equivocal patients experienced primary VZV infection. Furthermore, while no difference in IgA/IgG level was found regarding patient age, IgM level was significantly higher in young adults. The CLIA approach-based detection kit for diagnosing VZV-gE-specific IgA, IgG, and IgM is simple, suitable for high-throughput routine analysis situations, and provides enhanced specificity compared to ELISA.

Effect of the varicella vaccination implementation on the development of herpes zoster in children and adolescents

Herpes zoster (HZ) is an infectious disease caused by latent varicella-zoster virus reactivation. There are conflicting reports on the varicella vaccine's effect on the incidence of HZ in children and adolescents. This study aimed to determine the impact of the single dose of varicella vaccination on HZ prevalence during childhood and adolescence. The study included children and adolescents aged <18 years who presented to the dermatology outpatient clinic between 2005 and 2019 and were diagnosed with HZ. Considering that the universal vaccination program started to be implemented in Turkey in 2013, non-vaccinated cases in the prevaccination period, vaccinated cases in the postvaccination period, and non-vaccinated patients in the postvaccination period were compared in terms of HZ prevalence and demographic features. After the initiation of the varicella vaccination program, the prevalence of HZ was found to decrease by 24.7% in all. The HZ prevalence was significantly reduced in vaccinated children, while the rate of decrease in non-vaccinated children was low (58.6% and 16.4%, respectively). The median age of the non-vaccinated cases in the postvaccination period (10 [min 0.5-max 17] years) was significantly higher compared to the other groups (p < 0.001). The number of cases aged <2 years was the highest in the vaccinated group (p < 0.001). Administration of a single dose of varicella vaccine was insufficient to decrease the prevalence of HZ <18 years of age. In the post-vaccination period, the frequency of HZ in unvaccinated cases increased in adolescence. In vaccinated children, HZ seems to develop at an earlier age.

Varicella zoster virus vaccines: an update

Varicella zoster virus (VZV) is the etiological agent of varicella, a highly infectious, self-limiting disease with serious complications. The decline in cell-mediated immunity (CMI) that occurs with aging or immunodepression causes a reactivation of the latent VZV as herpes zoster (HZ). Prevention of VZV through varicella vaccination strategies allows to avoid the primary infection in newborns and susceptible subjects. Available monovalent and combined VZV vaccines are effective, safe and generally well tolerated. Universal varicella vaccination has significantly impacted on incidence, complications and deaths related to this disease. Prevention of HZ through vaccination is a priority to avoid the significant burden of its incidence and complications. Currently two HZ vaccines are available. The recombinant zoster vaccine (RZV), approved by the FDA in 2017 and Zoster Vaccine Live (ZVL) licensed in the United States by the FDA in 2006. The advisory committee on immunization practices (ACIP) preferentially recommends RZV. ZVL remains an option for prevention of HZ in immunocompetent adults aged ≥60 years, although the CMI tends to wane a few years after vaccination.

Susceptibility for varicella and factors associated with immunity among pregnant women in a tertiary care hospital in Sri Lanka- a cross-sectional study

BACKGROUND

Varicella during pregnancy can lead to serious maternal and fetal consequences. Although an effective vaccine is available it is not incorporated in to the routine vaccination programs in most of the Asian countries. Objectives of the study were to determine the susceptibility to varicella and factors associated with immunity, among a group of pregnant women attending to a tertiary care hospital in Sri Lanka.

METHODS

A hospital based descriptive cross sectional study was carried out at De Soyza maternity Hospital, Colombo. A sample of 385 pregnant women was selected. Data were collected through an interviewer administered questionnaire; presence of varicella IgG in blood was assessed by a validated commercial ELISA (Enzyme Linked Immunosorbant Assay.

RESULTS

The sample had a mean age of 28.5 years and majority was educated beyond General Certificate of Education (GCE) Ordinary Level. We found that 34% of study population was susceptible for the infection. A past history of varicella had a 89.5% positive predictive value and 53.1% negative predictive value for varicella immunity. Varicella sero-positivity was only associated with a lower educational level and number of childhood household members more than four. There was no association of sero-positivity with age.

CONCLUSION

This study demonstrates that a significant proportion of pregnant women of the study population are varicella-susceptible. Pre-pregnancy screening and preventive strategies including vaccination should be evaluated. History of past varicella infection could be a useful screening tool to exclude patients for vaccination.

Implementing Universal Varicella Vaccination in Europe: The Path Forward

Varicella is a common vaccine-preventable disease that usually presents as a mild disorder but can lead to severe complications. Before the implementation of universal varicella vaccination (UVV) in some European countries, the burden of varicella disease was broadly similar across the region. Despite this, countries adopted heterogeneous varicella vaccination strategies. UVV is currently recommended in 12 European countries. Known barriers to UVV implementation in Europe include (1) a perceived low disease burden and low public health priority; (2) cost-effectiveness and funding availability; (3) concerns related to a shift in varicella disease and incidence of herpes zoster and (4) safety concerns related to measles, mumps, rubella and varicella-associated febrile seizures after the first dose. Countries that implemented UVV experienced decreases in varicella incidence, hospitalizations and complications, showing overall beneficial impact. Alternative strategies targeting susceptible individuals at higher risk of complications have been less effective. This article discusses ways to overcome the barriers to move varicella forward as a truly vaccine preventable disease.

Customs officers in relation to viral infections, tuberculosis, psittacosis and environmental health risk

Customs Service is a financial authority responsible for controlling the flow of importation and exportation goods in each country and for collecting the relevant taxes. Customs officers are considered as 'high-demand' and 'high-responsibility' governmental officials, which constitute members of multidisciplinary teams at the local, as well as international level and collaborate with different authorities, including medical officers. Despite limited data in the medical literature, customs officers are considered as a 'high-risk' occupational group for infections and environmental health risk. During the severe acute respiratory syndrome (SARS) and influenza A/H1N1 pandemic outbreaks in 2003 and 2009, respectively, customs officers had a fundamental front-line input in the establishment of the recommended at that time border measures. In Belgium in 1994, a psittacosis outbreak occurred in customs officers following their exposure to illegally imported parakeets. During the recent increased immigration proceedings, customs officers have been involved in detaining unauthorized populations for various infectious diseases, such as tuberculosis, varicella and measles. Occupational risk for customs officers also includes noise-induced hearing loss, exposure to diesel engine emission and stored tobacco and occupational stress due to their increased time-schedule and decision-making duties. In this review, we discuss customs officers' occupational risk towards environmental and infectious factors, including viral infections, tuberculosis and psittacosis.

[From the licensure of vaccines to the recommendation of the Standing Committee on Vaccination in Germany : criteria for the assessment of benefits and risks]

Vaccines are among the most effective preventive measures in modern medicine and have led to a dramatic decline and-for a few diseases-even to the elimination of severely infectious diseases. There are some particularities of the risk-benefit assessment of vaccines compared with that of therapeutic drugs. These include the fact that vaccines are applied to healthy individuals with the aim of preventing an infectious disease, while therapeutic drugs are administered to sick people to cure them of an already acquired disease. The acceptable level of risk associated with the application of a vaccine is therefore much lower. In addition, high vaccination coverage can lead to population-level effects (e.g., the indirect protection of unvaccinated individuals) that can confer additional benefits to the population overall. When a marketing authorization application (MAA) for a novel vaccine is evaluated, conclusions are made regarding its quality, safety, and efficacy, and a benefit-risk assessment is carried out accordingly. In contrast, when deciding on the introduction of a new vaccine into a national immunization program or on a recommendation for a specific risk-group, the focus is shifted to considerations of how a licensed vaccine can be best used in a population (e.g., which immunization strategy is most effective in preventing deaths or hospitalizations, or in reducing treatment costs for the health care system). Stringent assessment criteria have been developed that require a robust safety analysis before a new vaccine is administered to humans for the first time in pre-licensure studies. Similarly, criteria are applied for calculating the benefit-risk ratio at the time of the licensure of a new vaccine in addition to during the entire post-licensure period. However, when deciding if and how a licensed vaccine can best be integrated into an existing immunization program, additional criteria are applied that are different, yet complementary to those applied for granting a marketing authorization. These decisions require-in addition to considerations of vaccine quality, vaccine efficacy and safety-conclusions regarding population-level effects combined with an integrative analysis of the local context (e.g., local epidemiology, cost-effectiveness, and acceptance by the population). To serve these objectives, national authorities such as the Standing Committee on Vaccination in Germany (STIKO) have been established to integrate globally developed vaccines into the national context of immunization strategies.

The temporal impact of aging on the burden of herpes zoster

Background

The risk of Herpes Zoster (HZ) increases with age and various studies have also demonstrated an increasing HZ incidence globally. Simultaneously, the global trend of an aging population has placed a greater burden on the healthcare system. This study aims to estimate the potential burden of HZ over time accounting for the increasing trends of both HZ incidence and global aging.

Methods

A recent systematic review on HZ incidence identified studies that evaluated the temporal effects of HZ incidence. Data from the identified studies were extracted to estimate the trend of HZ incidence in the ≥65-year-old age cohort. The incidence rates were estimated up to the year 2030 using two scenarios: a linear extrapolation and a last observation carried forward. Three countries were chosen to perform the analysis on: Australia, Japan and the United States.

Results

The incidence data from the three countries showed an average annual increase between 2.35 and 3.74% over the time period of the studies selected. The elderly population for the US, Japan and Australia are expected to increase by 55, 10 and 53% respectively by the year 2030 compared to the levels in 2015. Under the first scenario between 2001 and 2030, the number of annual incident cases of HZ in those aged ≥65 years is expected to increase by +343% (293,785 to 1,303,328), +176% (158,616 to 437,867) and +376% (18,105 to 86,268) in the US, Japan and Australia respectively while those for the second scenario are +150%, +83% and +223% respectively. In the US alone, the estimated annual cost of HZ-related cases in the ≥65 age cohort is approximately 4.74 Billion US$ in 2030.

Conclusions

The increasing incidence of HZ coupled with the demographic trends (i.e., aging population and greater life expectancy) in many countries are likely to imply a rising economic burden of HZ on already constrained healthcare budgets.

Cost of shingles: population based burden of disease analysis of herpes zoster and postherpetic neuralgia

Background

Around 30% of the population will experience herpes zoster (HZ), 10% of whom develop postherpetic neuralgia (PHN). Together, these illnesses produce a significant economic burden to the healthcare system.

Methods

Administrative healthcare data collected over the period of April 1^st 1997 to March 31^st 2014 were analyzed to determine the healthcare system burden of HZ using direct medical costs. Episodes of HZ were identified using international classification of disease (ICD) codes. Trends in age-adjusted (AA) HZ-rates were analyzed by piecewise-regression. Total annual and per-episode costs were determined for drug treatment, medical care, and hospitalizations within each year.

Results

The incidence of HZ increased by 49.5% from 1997/98 to 2013/14. Piecewise-regression of AA-rates revealed a steady AA-rate of 4.7 episodes/1000 person-years (PY) from 1997/98 to a breakpoint in 2008/09, after which rates began to increase reaching 5.7 episodes/1000 PY in 2013/14.

Drug costs rose significantly (p <0.03) from $89.77/episode (95% CI: $82.96, $96.59) to $127.34/episode (95% CI: $117.24, $137.44). Medical costs increased (p <0.0001) from $57.98/episode (95% CI; $55.26, $60.70) to $78.84/episode (95% CI; $74.08, $83.61). Hospitalization rates declined from 3.10% in 1997/98 to 1.36% in 2011/12, resulting in cost dropping from $397/episode (95% CI; $284, $511) to $195/episode (95% CI; $129, $260).

Total annual costs of HZ and PHN were $1,997,183 in 2011/12, 4.7% lower than the 1997/98 costs of $2,095,633.

Conclusion

A significant increase in annual number of HZ cases was observed, driven largely by demographic factors. A 21% increase in the AA-incidence reveals changes in HZ rates beyond those expected by population shifts.

The large increase in incidence of HZ, with rising per episode medical and prescription costs were offset by dramatic drops in hospitalization rates, the net effect of which has been to hold the total costs relatively constant. However, the decrease in hospitalization rates slowed over the last half of the study, settling at 1.3% in the last 4 study years. The likely future of HZ burden is one of rising costs, primarily driven by the demographic shifts of an increasing and aging population.

Factors associated with age of onset of herpes zoster ophthalmicus

PURPOSE

The aim of this study was to evaluate factors associated with the age of onset of herpes zoster ophthalmicus (HZO) in the era of varicella vaccination.

METHODS

A retrospective series of 400 subjects with a diagnosis of HZO, and an analysis of public health databases. Variables studied included the age at onset, period of disease onset (1996-2004 and 2005-2012), sex, smoking habits, diabetes status, autoimmunity, and immunosuppressed status. Community data were gathered from the Oklahoma Outpatient Surgery Discharge Public Use Data File and the United States Census' American Community Survey data set.

RESULTS

The mean onset age was significantly lower for 2005 to 2012 as compared with 1996 to 2004 among females (mean decrease, 9.3 years; 95% confidence interval, 4.6-13.9 years; P < 0.0001), but the mean onset age was similar between the 2 periods among males (P = 0.640). Whereas 32.3% of the patients with zoster were <60 years old in 1996 to 2004, compared with 44.8% in the 2005 to 2012 period (χ test: P = 0.017). In the multivariate model, smokers were found to have disease onset 11.5 (95% confidence interval, 6.9-16.1) years younger than nonsmokers.

CONCLUSIONS

The proportion of younger patients with HZO increased, whereas the institutional and community data sets demonstrate a downward shift of the average age of onset of HZO among females. This may be an effect of widespread childhood varicella vaccination. Immunosuppression and smoking were also associated with a younger age of onset of HZO. This has implications for clinical care of patients at risk for developing HZO, as well as public health and vaccination policies.

Epidemiology of pediatric herpes zoster after varicella infection: a population-based study

BACKGROUND

There are limited population-based data regarding pediatric herpes zoster (HZ).

METHODS

Children aged <12 years with varicella infections between 2000 and 2006 were identified from a national population-based database and followed-up for a diagnosis of HZ until December 2008. Since a routine varicella vaccination program was started in 2004, vaccinated children without medically attended varicella were identified between 2004 and 2006, and followed-up for a diagnosis of HZ until December 2008.

RESULTS

Of 27 517 children with medically attended varicella, 428 developed HZ. The incidence of HZ was 262.1 per 100 000 person-years. Of 25 132 vaccinated children without medically attended varicella, 106 developed HZ. The incidence of HZ was 93.3 per 100 000 person-years. The mean duration from varicella to HZ was 4.12 years. Children diagnosed with varicella at aged <2 years had a higher incidence (P < .001) and shorter duration (P = .04) than those diagnosed aged ≧2 years. Children diagnosed with varicella aged ≥2 but <8 years had a significantly increased incidence of HZ after than before the vaccination program (relative risk = 1.85 at 3 years of follow-up, P = .03). Children with varicella infections had a significantly greater risk of HZ than vaccinated children without a history of varicella (relative risk = 2.31 at 4 years of follow-up, P < .001).

CONCLUSIONS

This study demonstrates the population-based epidemiologic characteristics of pediatric HZ among those who contracted varicella. In the early postvaricella vaccination period, an increased HZ incidence was observed among children with varicella infection aged ≥2 years.

The impact of ten years of infant universal Varicella vaccination in Sicily, Italy (2003-2012)

INTRODUCTION

Universal varicella vaccination in Sicily was introduced in infant population since 2003, with a rapidly increasing coverage. Aim of the present study was to analyze changes in the epidemiology of varicella since the introduction of universal vaccination.

METHODS

The study was performed by analyzing Sicilian administrative/clinical data on varicella case notifications and hospitalizations from 2003 to 2012 (ICD-9-CM discharge diagnosis codes 052 and 052.×). MMR+V and V coverage were also calculated for each birth cohort. Moreover, blood samples drawn in 2013/2014 from general population stratified by age were tested for varicella antibodies.

RESULTS

From 2003 to 2012, 15 433 varicella cases were notified with a decreasing temporal trend (1.1/1000 population in 2003 to 0.1/1000 in 2012) (P < 0.001). In the same period, a total of 1145 patients were hospitalized with a diagnosis of varicella, with a 6-fold reduced risk of hospitalization over time (from 4.8 to 0.8/100 000 population per year; P < 0.001). Varicella vaccination coverage rates increased from 40% (2001 birth cohort) to 85% (2010 birth cohort), and inversely correlated with both notification and hospitalization rates (P < 0.001). Finally, 80.0% of subjects enrolled in the seroepidemiological survey were positive for varicella and seroprevalence increased significantly with age in both sexes (P < 0.001).

DISCUSSION

The results show the impact of infant universal varicella vaccination in Sicily. Noteworthy, notifications and hospitalizations for varicella have significantly decreased after the introduction of universal vaccination, confirming the effectiveness of the adopted strategy.

Prevention of shingles by varicella zoster virus vaccination

Herpes zoster is caused by reactivation from previous varicella zoster virus (VZV) infection, and affects millions of people worldwide. It primarily affects older adults and those with immune system dysfunction, most likely as a result of reduced or lost VZV-specific cell-mediated immunity. Complications include post-herpetic neuralgia, a potentially debilitating and chronic pain syndrome. Current treatment of herpes zoster and post-herpetic neuralgia involves antiviral agents and analgesics, and is associated with significant economic cost. Results from several clinical trials have determined that a live, attenuated VZV vaccine using the Oka/Merck strain (Zostavax) is safe, elevates VZV-specific cell-mediated immunity, and significantly reduces the incidence of herpes zoster and post-herpetic neuralgia in people over 60 years of age. Regulatory approval has recently been obtained and once launched, it is expected that this vaccine will significantly reduce the morbidity and financial costs associated with herpes zoster. Durability of vaccine response and possible booster vaccination will still need to be determined.

Seroprevalences of varicella-zoster virus, herpes simplex virus and cytomegalovirus in a cross-sectional study in Mexico

We estimated the seroprevalences of varicella-zoster virus (VZV), herpes simplex virus (HSV) and cytomegalovirus (CMV) in this cross-sectional database study. Serum samples collected during the National Health and Nutrition survey (ENSANUT 2006) were obtained from subjects aged 1-70 years between January and October 2010. Serological assays for the determination of antibodies against VZV, HSV and CMV were performed. The overall seroprevalences of VZV, HSV-1, HSV-2 and CMV were 85.8%, 80.9%, 9.9% and 89.2%, respectively. Seroprevalences of VZV, HSV-1 and CMV were comparable between males and females. For HSV-2, although the seroprevalence rate was higher in females when compared to males, this difference in seroprevalence was not statistically significant. Seroprevalence rates for VZV, HSV-1, HSV-2 and CMV increased with age (p-value<.0001). Differences in seroprevalence rate for VZV by socioeconomic status (SES) were significant (p-value<0001). Results of the serological analyses reported high VZV seroprevalence, indicating high transmission in the Mexican population with children and adolescents at risk of acquiring VZV. Global HSV-1 seroprevalence was high, especially in adults. HSV-1 and HSV-2 seroprevalences were consistently higher in women than men, particularly for HSV-2. CMV seroprevalence was higher in Mexico when compared to developed countries. Seroepidemiological data on VZV supports the fact that varicella vaccination may serve as an alternative effective solution to reduce transmission in the Mexican population. For CMV and HSV, since no vaccines are available, activities to reduce transmission are important to reduce the risk of complications and therefore need to be considered.

Zostavax : a subcutaneous vaccine for the prevention of herpes zoster

INTRODUCTION

Herpes zoster (HZ) occurs as a reactivation of dormant varicella zoster virus (VZV), and occurs more frequently in the aging population or the immunocompromised due to waning cell-mediated immunity. Up to 1 million cases of HZ are reported annually in the USA with an estimated 10 - 30% of the population being affected by shingles in their lifetime. HZ is a debilitating illness, and while mortality is low, morbidity remains a significant cause for concern with prevention efforts aimed at reducing VZV reactivation and its complications. The HZ vaccine was approved by the US Food and Drug Administration for individuals aged 50-years or older. However, the Center for Disease Control and Prevention's Advisory Committee for Immunization Practices recommends the vaccine in individuals aged 60-years or older.

AREAS COVERED

Recent literature investigating the efficacy and indications of live attenuated zoster vaccine.

EXPERT OPINION

Live attenuated zoster vaccine is safe and efficacious in preventing HZ and decreasing the morbidity associated with postherpetic neuralgia. The vaccine is FDA approved in individuals aged 50-years or older but further studies are warranted to investigate the vaccine's efficacy in immunosuppressed and immunocompromised patients.

Dynamic transmission modeling: a report of the ISPOR-SMDM Modeling Good Research Practices Task Force Working Group-5

The transmissible nature of communicable diseases is what sets them apart from other diseases modeled by health economists. The probability of a susceptible individual becoming infected at any one point in time (the force of infection) is related to the number of infectious individuals in the population, will change over time, and will feed back into the future force of infection. These nonlinear interactions produce transmission dynamics that require specific consideration when modeling an intervention that has an impact on the transmission of a pathogen. Best practices for designing and building these models are set out in this paper.

Dynamic transmission modeling: a report of the ISPOR-SMDM Modeling Good Research Practices Task Force--5

The transmissible nature of communicable diseases is what sets them apart from other diseases modeled by health economists. The probability of a susceptible individual becoming infected at any one point in time (the force of infection) is related to the number of infectious individuals in the population, will change over time, and will feed back into the future force of infection. These nonlinear interactions produce transmission dynamics that require specific consideration when modeling an intervention that has an impact on the transmission of a pathogen. Best practices for designing and building these models are set out in this article.

Epidemiological characteristics and societal burden of varicella zoster virus in the Netherlands

Background

Varicella and herpes zoster are both caused by varicella zoster virus (VZV) infection or reactivation and may lead to complications associated with a (severe) societal burden. Because the epidemiology of VZV-related diseases in the Netherlands remains largely unknown or incomplete, the main objective of this study was to study the primary care incidence, associated complications and health care resource use.

Methods

We investigated the incidence of VZV complications in the Dutch general practitioner (GP) practices and pharmacies in a retrospective population-based cohort study (2004–2008) based on longitudinal GP data including free text fields, hospital referral and discharge letters from approximately 165,000 patients.

Results

The average annual incidence of varicella GP-consultations was 51.5 per 10,000 (95% CI 44.4-58.7) overall; 465.5 per 10,000 for 0–1 year-olds; 610.8 per 10,000 for 1–4 year-olds; 153.5 per 10,000 for 5–9 year-olds; 8,3 per 10,000 for >10 year olds. When only ICPC coded diagnoses were analyzed the incidence was 27% lower. The proportion of complications among varicella patients was 34.9%. Most frequently complications were upper respiratory tract infections. Almost half of the varicella patients received medication. The referral rate based on GP consultations was 1.7%. The average annual incidence of herpes zoster GP-consultations was 47.5 per 10,000 (95% CI 40.6-54.4). The incidence increased with age; 32.8 per 10,000 for <60 year-olds; 93.1 per 10,000 for 60–64 year-olds and 113.2 per 10,000 for >65 year olds. When estimating herpes zoster incidence only on ICPC coded information, the incidence was 28% lower. The complication rate of herpes zoster was 32.9%. Post herpetic neuralgia was seen most often. Of patients diagnosed with herpes zoster 67.8% received medication. The referral rate based on GP consultations was 3.5%.

Conclusions

For varicella the highest incidence of GP-consultations was found in 1–4 year-olds, for herpes zoster in the >65 years olds. The occurrence of complications was not age-dependent but varies per complication. When estimating incidence of VZV-related diseases in primary care, based on diagnostic codes only, one should be aware of a gross underestimation of the incidence. Our analysis may have important implications for the outcomes of upcoming cost-effectiveness analyses on VZV vaccination.

Population-based incidence of herpes zoster after introduction of a publicly funded varicella vaccination program

BACKGROUND

Past varicella infection (chicken pox) may reactivate into herpes zoster (shingles). Varicella vaccination leads to a reduction in cases of varicella that may in turn increase herpes zoster rates due to reduction in the immune boosting effect of exposure to varicella zoster virus against varicella reactivation. We assessed the impact of childhood varicella vaccination in Ontario, Canada on zoster incidence and healthcare visits, and established baseline zoster rates prior to zoster vaccine introduction.

METHODS

We used population-based, administrative databases to identify zoster incidence and healthcare use from April 1992 to March 2010.

RESULTS

After routine varicella vaccination, zoster incidence rates decreased 29% for children aged 0-9 and changed minimally for other ages. Age-standardized rates of hospitalizations during the study period declined by 53%, while outpatient rates declined by 9%. The annual zoster incidence for those 60 or older was 740 per 100,000.

CONCLUSIONS

In the early post-varicella vaccination period, incidence rates of medically attended herpes zoster did not increase for the overall population and decreased moderately for children 9 years and younger, the age group targeted for varicella vaccination.

The incidence of varicella and herpes zoster in Taiwan during a period of increasing varicella vaccine coverage, 2000-2008

The introduction and the widespread use of the varicella vaccine in Taiwan has led to a 75-80% decrease in the incidence of varicella in children. However the vaccine's long-term impact on the incidence of herpes zoster (HZ) has attracted attention. By controlling gender, underlying diseases, and age effects, a Poisson regression was applied on the 2000-2008 chart records of 240 000 randomly selected residents who enrolled in the Universal National Health Insurance. The results show that, as the vaccine coverage in children increases, the incidence of varicella decreases. However, the incidence of HZ increased even before the implementation of the free varicella vaccination programme in 2004, particularly in females. The increase in the incidence of HZ cannot be entirely and directly attributed to the widespread vaccination of children. Continuous monitoring is needed to understand the secular trends in HZ before and after varicella vaccination in Taiwan and in other countries.

Management and prevention of herpes zoster: A Canadian perspective

Varicella-zoster virus reactivation leads to herpes zoster - the main complication of which is postherpetic neuralgia (PHN). Rapid antiviral therapy initiated within 72 h of rash onset has been shown to accelerate rash healing, reduce the duration of acute pain and, to some extent, attenuate the development and duration of PHN. Other adjunctive therapies such as analgesics, antidepressants and some anticonvulsants are frequently required in the management of severe PHN. A live, attenuated zoster vaccine has been recently shown to significantly decrease herpes zoster incidence, PHN and the overall burden of illness when administered to adults older than 60 years of age. This new prophylactic modality has been reported to be cost-effective in the Canadian context, especially in the 60- to 75-year-old age group.

What types of contacts are important for the spread of infections?: using contact survey data to explore European mixing patterns

Knowledge of the determinants of infectious disease transmission is a public health priority as it allows the design of optimal control strategies for endemic or emerging infections. We analyse a detailed dataset on contact patterns across five European countries and use available serological profiles for varicella and parvovirus B19 infections to identify the types of contact that may be most relevant for transmission. We show that models informed by contact data fit well the observed serological profiles of both infections. We find that intimate types of contacts explain the pattern of acquisition of serological markers by age better than other types of social contacts. We observe similar patterns in each of the countries analysed, suggesting that there are consistent biological mechanisms at work.

Varicella susceptibility and transmission dynamics in Slovenia

BACKGROUND

A cross-sectional, age-stratified study was conducted to determine varicella-zoster seroprevalence and force of infection in Slovenia.

METHODS

3689 serum samples were tested for VZV IgG antibodies with an enzyme immunoassay. Semiparametric and parametric modelling were used to estimate the force of infection.

RESULTS

Overall, 85.6% of serum samples were seropositive. Age-specific prevalence rose rapidly in preschool children and over 90% of 8 years old tested positive for VZV. However, 2.8% of serum samples among women of childbearing age were seronegative. Semiparametric modelling yielded force of infection estimates of 0.182 (95% CI 0.158-0.206), 0.367 (95% CI 0.285-0.448) and 0.008 (95% CI 0.0-0.032) for age groups 0.5- < 6, 6-11 and >or=12 years, respectively, and 0.175 (95% CI 0.147-0.202), 0.391 (95% CI 0.303-0.480) and 0.025 (95% CI 0.003-0.046) for age groups 0.5- < 5, 5-9 and >or=10 years, respectively.

CONCLUSIONS

Regardless of the age grouping used, the highest transmission occurred in children in their first years of school.

Prevalence of varicella-zoster virus genotypes in Australia characterized by high-resolution melt analysis and ORF22 gene analyses

DNA sequence variation analysis has divided varicella-zoster virus (VZV; Human herpesvirus 3) into distinct geographical clades: European, Asian, African and Japanese. These genotypes are becoming increasingly prevalent within regions atypical to their original source and there has been the suggestion of recombination between genotypes. Seventy-eight clinical isolates from hospitalized patients with varicella were collected in New South Wales, the Northern Territory, Western Australia and Victoria from 2006 to 2009. The wild-type strains and the vaccine strain (vOka) were differentiated by single nucleotide polymorphism detection using high-resolution melt analysis of five target genes (ORF1, -21, -37, -60 and -62), and by DNA sequence analysis of a 484 bp region of ORF22. Phylogenetic analysis showed that 46 % (36/78) of the clinical isolates were European clade 1 (C/E1) strains, 21 % (16/78) were European clade 3 (B/E2) strains, 12 % (9/78) were Asian/African clade 5 (A/M1) strains, 10 % (8/78) were clade 4 (J2/M2), 6 % (5/78) were clade 2 (J/J) and 5 % (4/78) belonged to the novel clade VI. No significant association was shown between VZV genotype and region, age or gender. Although European strains were most common, the results suggest an increase in African/Asian, Japanese and clade VI genotypes circulating in Australia.

Modelling the impact of varicella vaccination on varicella and zoster

It has been suggested that the incidence of herpes zoster may increase due to lack of natural boosting under large-scale vaccination with the varicella vaccine. To study the possibility and magnitude of such negative consequences of mass vaccination, we built a mathematical model of varicella and zoster epidemiology in the Finnish population. The model was based on serological data on varicella infection, case-notification data on zoster, and new knowledge about close contacts relevant to transmission of infection. According to the analysis, a childhood programme against varicella will increase the incidence of zoster by one to more than two thirds in the next 50 years. This will be due to increase in case numbers in the 35 years age groups. However, high vaccine coverage and a two-dose programme will be very effective in stopping varicella transmission in the population.

Varicella zoster virus vaccines: effective, but concerns linger

Both varicella and herpes zoster (HZ) can cause severe disease in certain age groups. The cell-mediated immune (CMI) response to the varicella zoster virus (VZV) is critical in preventing a recurrence of VZV. The varicella vaccine has markedly decreased the morbidity and mortality associated with varicella, but concerns linger about the cost and frequency of vaccine administration and the long-term effects on both adult varicella and HZ epidemiology in the individual and in the population. Therapy for HZ with an antiviral is only partially effective. A zoster vaccine is now available that boosts the CMI immune reaction to VZV in individuals and has proven safe and partially effective in preventing both HZ and post-herpetic neuralgia. Concerns about the zoster vaccine include the costs of administration, the overall health-care costs to society, and the acceptance and implementation of the vaccine in the elderly. Because of altered immune responses to VZV as a result of universal varicella vaccination it becomes even more compelling in the future to have a zoster vaccine ready to boost the CMI response to a sufficient level to prevent HZ. The 2 vaccines are intertwined in the future epidemiology of VZV disease.

Herpes zoster and postherpetic neuralgia: past, present and future

OBJECTIVES

The history behind the current understanding of the varicella-zoster virus and its relationship to the pain conditions caused by shingles and postherpetic neuralgia are reviewed. The framework for the current conceptualization is Hope-Simpson's latency hypothesis. Data from recent work in virology, neuroanatomy and epidemiology are reviewed, as is work using varicella-zoster virus-infected animals. The recent data largely confirm Hope-Simpson's hypothesis and extend it significantly.

Herpes Zoster and Postherpetic Neuralgia: a review of the effects of vaccination

Herpes zoster (HZ) results from reactivation of varicella zoster virus which has been persistent but clinically latent in dorsal root and cranial nerve ganglia since primary infection, usually as a child, with varicella (chicken pox). HZ affects 20-30% of individuals during their lifetime and up to 50% of those > or =80 years old. Although serious life- or sight-threatening complications occur rarely, postherpetic neuralgia (PHN) is the most common complication. Both HZ and PHN are most common in the elderly. Declining cell-mediated immunity resulting from immune senescence appears to be the cause. Incidence of HZ is also high in individuals who are immunocompromised as a result of disease or its treatment. HZ also occurs in younger and fit individuals but is usually mild and complications are rare. Current management of HZ with antiviral drugs and analgesics attains quite good control of acute pain and skin rash but offers only partial protection against PHN. Other strategies studied to prevent PHN such as nerve blocks are relatively ineffective and clinically impractical. Although several drug classes are used to manage PHN, numbers needed to treat to obtain 50% pain reduction range from approx. 2.5-5 and adverse effects are common. The elderly population is growing and thus the number of HZ and PHN susceptible individuals is increasing. HZ and PHN are expensive in terms of suffering, loss of independence and healthcare costs. Significant numbers of the elderly with HZ require hospitalization. Short-term illness in the elderly can lead to long-term loss of independence. A live attenuated herpes zoster vaccine has been studied in a large number of subjects and shown to reduce incidence of HZ as well as incidence and severity of PHN. The safety profile of the vaccine is good, local soreness at the injection site being the only common adverse event. Health economics studies suggest that vaccination of adults about 60 years of age would be cost effective. Duration of protection following vaccination is the subject of ongoing surveillance, as is the potential benefit of vaccinating younger and sicker members of the population.

Varicella immunisation practice: Implications for provision of a recommended, non-funded vaccine

AIM

In Australia in 2003 a two-tiered immunisation schedule was introduced consisting of funded (National Immunisation Program) and non-funded but recommended vaccines (Best Practice Schedule), including varicella vaccine. The aim of this study was to examine immunisation practice when a vaccine is recommended but not funded by Government.

METHODS

A survey was sent to 600 randomly selected general practitioners (GPs) in South Australia between June and August 2005, prior to provision of Federal funding for varicella vaccine.

RESULTS

Although varicella was considered an important disease to prevent by 89% of GPs, only 25% of GPs always discussed the non-funded immunisation with parents at the time of a routine immunisation visit. Female GPs were more likely to discuss immunisation with recommended, non-funded vaccines than male GPs. Those who were supportive of varicella prevention were more likely to discuss immunisation with the non-funded vaccine. GPs who always provided information about the disease were more likely to have parents accept their advice about varicella vaccine (62.7%) than those who never provided information (40%). GPs reported parental refusal of varicella vaccine was due to the cost and perception that varicella is a mild disease.

CONCLUSIONS

The results of this study showed variability in prescribing practices for a non-funded vaccine. Recommending a vaccine without provision of funding may lead to 'mixed messages' for immunisation providers and parents with resultant low coverage. Funding a vaccine is likely to reduce variability in provision of the vaccine and improve coverage in the community.

Herpes zoster and postherpetic neuralgia: optimizing management in the elderly patient

Herpes zoster (HZ) results from reactivation of varicella-zoster virus (VZV) that has been persistent and clinically dormant in spinal ganglia or cranial sensory nerves since primary infection with VZV. The most common reason for reactivation is a decline in zoster-specific cell mediated immunity as a result of aging (immunosenescence). More than two-thirds of HZ cases occur in people >or=60 years of age. HZ incidence is higher in persons who are immunocompromised as a result of disease (e.g. malignancies such as lymphoma, HIV/AIDS, diabetes mellitus) or treatments such as chemotherapy and radiotherapy. HZ incidence is also increased by therapeutic immune suppression following organ transplantation and in patients taking high-dose corticosteroids. However, HZ may occur in otherwise healthy young people. Although serious and life-threatening complications sometimes occur, the most common complication is postherpetic neuralgia (PHN), which may persist for months or years and is significantly resistant to treatment despite substantial advances in the understanding of its pathological mechanisms. The medical and social costs of HZ and PHN are high, particularly in older patients. Prevention of PHN in patients with HZ is unsatisfactory although antiviral drugs reduce the duration of pain after HZ. A live attenuated vaccine has been shown to reduce the incidence of HZ and PHN as well as the burden of illness in subjects aged >or=60 years. In view of the increasing numbers of elderly persons in the population and the poor outcomes of PHN treatment, vaccination against HZ at approximately 60 years of age appears to be an appropriate strategy.

Herpes zoster-related hospitalizations and expenditures before and after introduction of the varicella vaccine in the United States

OBJECTIVE

With childhood varicella vaccination in the United States have come concerns that the incidence of herpes zoster may increase, because of diminishing natural exposure to varicella and consequent reactivation of latent varicella zoster virus. We wanted to estimate the rate of herpes zoster-related hospitalizations and the associated hospital charges before and during the promotion of varicella vaccination in the United States.

DESIGN

A retrospective study of patients from the Nationwide Inpatient Sample for the years 1993-2004 who were hospitalized due to herpes zoster infection.

METHODS

We searched for diagnoses of herpes zoster (using the International Classification of Diseases, Ninth Revision, Clinical Modification codes starting with 053) in all 15 diagnostic-code fields included for hospital discharges in the Nationwide Inpatient Sample during 1993-2004. We designed our analysis to examine the rates of severe illness due to herpes zoster that resulted in hospitalization, as measured by the rates of herpes zoster-related hospital discharges (HZHDs). The annual population-adjusted rate of HZHDs (per 10,000 US population) and the annual inflation-adjusted total charges for HZHDs were the primary outcomes. Secondary outcomes included mean charges for HZHDs and the distribution of total charges for HZHDs by expected primary payer. Varicella-related hospital discharges (VRHDs) were identified by use of similar diagnosis-based methods, which were described in our previous study.

RESULTS

Population-adjusted rates of HZHDs did not change significantly from the prevaccination years (1993-1995) through the initial 5 years of the varicella vaccination period. Beginning in 2001, however, the rate of HZHDs overall began to increase, and by 2004 the overall rate was 2.5 HZHDs (95% confidence interval, 2.38-2.62) per 10,000 US population, significantly higher than any of the rates calculated during the years prior to 2002. Hospital charges for HZHDs overall increased by more than $700 million annually by 2004; in particular, we found that the herpes zoster vaccine-eligible population (ie, persons aged 60 years or older) accounted for 74% of the total annual hospital charges in 2004. The annual rate of VRHDs and the associated hospital charges decreased significantly from 1993 through 2004, but the decrease in hospitalizations and charges for VRHDs was less than the increase in hospitalizations and charges for HZHDs.

CONCLUSIONS

As the rates of VRHDs and the associated charges have decreased, there has been a significant increase in HZHDs and associated charges, disproportionately among older adults. Herpes zoster vaccine may mitigate these trends for HZHDs.

The epidemiology of Varicella Zoster Virus infection in Italy

Background

The epidemiological importance of varicella and zoster and the availability of an efficacious and safe vaccine have led to an important international debate regarding the suitability of mass vaccination. The objective of the study was to describe the epidemiology of varicella and zoster in Italy and to determine whether there have been changes with respect to observations provided by an analogous study conducted 8 years ago, in order to define the most appropriate vaccination strategy.

Methods

A number of data sources were evaluated, a cross-sectional population-based seroprevalence study was conducted on samples collected in 2004, and the results were compared with data obtained in 1996.

Results

The data from active and passive surveillance systems confirm that varicella is a widespread infectious disease which mainly affects children. VZV seroprevalence did not substantially differ from that found in the previous study. The sero-epidemiological profile in Italy is different from that in other European countries. In particular, the percentage of susceptible adolescents is at least nearly twice as high as in other European countries and in the age group 20–39 yrs, approximately 9% of individuals are susceptible to VZV.

Conclusion

The results of this study can contribute to evaluating the options for varicella vaccination. It is possible that in a few years, in all Italian Regions, there will exist the conditions necessary for implementing a mass vaccination campaign and that the large-scale availability of MMRV tetravalent vaccines will facilitate mass vaccination.