Varicella: epidemiological aspects and vaccination coverage in the Veneto Region

The clinical and economic costs associated with regional disparities in varicella vaccine coverage in Italy over 50 years (2020-2070)

Italy implemented two-dose universal varicella vaccination (UVV) regionally from 2003 to 2013 and nationally from 2017 onwards. Our objective was to analyze regional disparities in varicella outcomes resulting from disparities in vaccine coverage rates (VCRs) projected over a 50-year time-horizon (2020-2070). A previously published dynamic transmission model was updated to quantify the potential public health impact of the UVV program in Italy at the national and regional levels. Four 2-dose vaccine strategies utilizing monovalent (V) and quadrivalent (MMRV) vaccines were evaluated for each region: (A) MMRV-MSD/MMRV-MSD, (B) MMRV-GSK/MMRV-GSK, (C) V-MSD/MMRV-MSD, and (D) V-GSK/MMRV-GSK. Costs were reported in 2022 Euros. Costs and quality-adjusted life-years (QALYs) were discounted 3% annually. Under strategy A, the three regions with the lowest first-dose VCR reported increased varicella cases (+ 34.3%), hospitalizations (+ 20.0%), QALYs lost (+ 5.9%), payer costs (+ 22.2%), and societal costs (+ 14.6%) over the 50-year time-horizon compared to the three regions with highest first-dose VCR. Regions with low first-dose VCR were more sensitive to changes in VCR than high first-dose VCR regions. Results with respect to second-dose VCR were qualitatively similar, although smaller in magnitude. Results were similar across all vaccine strategies.

Varicella seroepidemiology and immunization in a cohort of future healthcare workers in the pre-vaccination era

OBJECTIVES

The goal of this study was to establish the seroprevalence of positive antibodies against varicella and compliance with varicella vaccination in the pre-vaccination era.

METHODS

A cohort of 10 683 Italian students from Padua University Medical School (from 2004 to 2019) were enrolled and classified as unvaccinated, vaccinated once, or vaccinated twice against varicella, according to their vaccination certificate. The antibody titre was measured and the seroprevalence of positive subjects was determined. Subjects with negative or equivocal antibodies were invited for vaccination, and then the antibody titre was retested.

RESULTS

Unvaccinated students were mostly seropositive (95.6%), compared with vaccinated students who were less seropositive (68.0% after one dose and 78.6% after two doses) and had significantly lower antibody titres (p < 0.0001). The post-test vaccination had a positive response rate of 85.4%: 67.4% after one dose and 91.4% after two doses.

CONCLUSIONS

In the pre-vaccination era, only 3.3% of future healthcare workers were vaccinated against varicella (1.1% once and 2.2% twice). Vaccination or revaccination of negative and equivocal individuals could reduce the number of susceptible people. Implementation of varicella vaccine (two doses) in healthcare workers is of primary importance to reduce the risk of transmission.

Epidemiological and clinical characteristics and the approach to infant chickenpox in primary care

Chickenpox is not common in the first year of life (infant varicella) and there is a lack of data on its presentation, especially in primary care. A year-long observational study (July 2015-2016) carried out by a research network of primary care pediatricians throughout Spain.Two hundred and sixty-four pediatricians gathered data from 358 cases of clinically diagnosed chickenpox in infants. The illness was considered mild in 78% of infants < 7 months compared to 65% in those aged 7 to 12 months (p = 0.0144). Fever (46%) was present in 35% of children ≤ 6 months compared to 55% in older children (p = 0.0005). The number of skin lesions was > 50 in 35% of children ≤ 6 months old compared to 47% in > 7 months (p = 0.0273). From the 2% of hospitalized children 86% were younger than 7 months. Oral antiviral treatment was given in 33% of cases ≤ 6 months compared to 18% in older patients (p = 0.0023). Doubts about administering the chickenpox vaccine at a later date were expressed by 18% of pediatricians.Conclusion: Chickenpox is considered benign, having a mild effect on most infants. There is less clinical effect in infants ≤ 6 months although this age group is hospitalized more and is prescribed more antiviral treatment. There are doubts among pediatricians about the subsequent need for vaccination. What is Known: • Chickenpox is uncommon and of uncertain evolution in the first year of life • Hospital admissions for chickenpox are more frequent in the first year of life What is New: • The course of chickenpox in the first year of life is mild, especially in infants younger than 7 months despite the fact they are hospitalized more and are treated more frequently with antivirals. Antivirals are prescribed to 1 in 4 children with chickenpox under 12 months of age. • Almost 50% of pediatricians recommend a subsequent vaccination against chickenpox especially if it occurs in the first 6 months of life.

Cross-sectional study on hospitalizations related to herpes zoster in an Italian region, 2008-2016

INTRODUCTION

To assess the burden of herpes zoster (HZ) by analyzing HZ-related hospital admissions.

METHODS

We conducted a population-based descriptive cross-sectional study on all hospitalizations for HZ among the resident population admitted to all public and accredited private hospitals in the Veneto Region (north-east Italy) during the years 2008-2016. HZ hospitalizations were identified from the International Classification of Diseases codes in the hospital discharge records.

RESULTS

During the period considered, we identified 3566 HZ-associated admissions, 194 (5.4%) of which were readmissions within 30 days. A complicated HZ diagnosis was mentioned for 44.4% of the patients admitted once and for 65.9% of those admitted twice. In the sample as a whole, 27.0% of patients had at least one comorbidity. Overall, our analysis revealed a gradual increase in hospitalizations with age for both genders, reaching a hospitalization rate for the population over 80 years old of 51.2 × 100,000 for males and 52.8 × 100,000 for females. The average hospitalization rate for HZ-related conditions during the years 2008-2016 was 7.7 per 100,000 population. Postherpetic neuralgia was diagnosed in 8.2% of hospitalizations, with no difference between the genders. The estimated overall cost of HZ-related conditions was approximately €2.7 million a year.

CONCLUSIONS

This study suggests that the burden of HZ and its impact on quality of life are of critical relevance to public health decision-making.

Impact of vaccination programs against measles, varicella and meningococcus C in Italy and in Tuscany and public health policies in the last decades

The World Health Organization (WHO) has established specific targets for control, elimination or eradication of some vaccine preventable infectious diseases, which were periodically updated. In Italy, WHO recommendations have been endorsed and implemented over time, through the national and regional health prevention plans. The aim of the study was to assess the impact of the immunization practices against measles, varicella and Neisseria meningitidis type C (Men C) in Italy and in Tuscany Region, during the last decades, by analyzing national and regional surveillance databases. Benefits of vaccination strategies were discussed from different points of view (clinical, epidemiological, economic, ethical, social and communicative). The implementation of measles, varicella and Men C vaccination, caused a considerable decrease of incidence rates over the years in Italy and in Tuscany too. However, in the last years, notifications of measles and Men C cases in subjects not targeted by immunization campaigns, in Italy and in Tuscany, are a cause for concern for public health and for the achievement of the elimination goals. Achieving and maintaining high vaccine coverage guarantees a decrease in the incidence of serious diseases and their clinical and economic consequences, but it is necessary to strengthen surveillance system of infectious diseases in order to monitor epidemiological trends. Moreover, outreach campaigns are necessary to raise awareness in the general population and create the culture of prevention with the same nationwide health goals for all.

[Decrease in the incidence of chickenpox in the Community of Madrid after universal childhood immunization. Years 2001-2015]

OBJECTIVE

Varicella vaccine was recommended in the Community of Madrid (CM) at 15months of age between November 2006 and December 2013. The objective was to describe the impact of vaccination on the incidence of varicella in the CM during the period 2001-2015.

DESIGN

A descriptive study of cases of varicella reported to the Sentinel Physician Network of the CM and the cases recorded in the Minimum Basic Data Set at hospital discharge was carried out. Total incidence of cases and of hospital admissions were calculated, as well as specific incidence by age and sex.

RESULTS

The incidence was 94.0% lower between 2012 and 2013 than between 2001 and 2003. Between 2014 and 2015 the incidence was 61.8% higher than between 2012 and 2013. The highest incidence was observed in children aged 0 to 4years except for 2010-2014, which was exceeded by the incidence in children aged 5 to 9. The trend in hospital admissions was also decreasing, with the highest incidence in children aged 0 to 1year, followed by 1-4years.

CONCLUSIONS

There has been a significant decrease in the incidence of cases and of hospital admissions by varicella in all age groups after the recommendation to vaccinate at 15months of age, which is compatible with the effectiveness of a dose and its ability to produce immunity group. The withdrawal of this recommendation between 2014 and 2015 has led to an increase in the incidence.

A postmarket safety comparison of 2 vaccination strategies for measles, mumps, rubella and varicella in Italy

It is strategically important to monitor the safety profile of vaccination schedules in order to achieve and maintain high levels of coverage. We analyzed the cohort of individuals actively invited for measles, mumps, rubella and varicella (MMRV) vaccination in the Veneto region (north-east Italy) from 8/1/2013 to 7/31/2014, assessing the onset of adverse events (AE) relating to 2 different vaccination strategies for MMRV (MMR+V vs MMRV). During the vaccination session at 14 months old, parents were given a form for recording local and systemic reactions to vaccinations for 4 weeks afterwards. Overall, 12,288 forms were returned, and 84.6% of them were included in this analysis (5,130 relating to MMR+V and 5,265 to MMRV); 37.3% of the sample reported no AEs, with no difference between the 2 groups. Local reactions were more common in the MMR+V group (9.6% vs 2.9%; RR 3.33; 95% CI 2.79-3.98), while there was no difference in general reactions between the 2 groups (50% MMR+V vs 52% MMRV). The events most often reported were "fever <39.5°C," which was more frequently associated with the MMRV strategy (p<0.001), and "skin blotches and marks," which occurred more often in the MMR+V group (p<0.001). Reports of "fever ≥39.5°C" were equally distributed between the 2 groups. Sixteen cases of febrile seizures were reported (0.14% in the MMR+V group and 0.17% in the MMRV group). Similar safety profiles were identified for the 2 vaccination strategies. Although the method used to record reactions to vaccination demanded considerable resources, it enabled important information to be collected on parents' perception of the AEs occurring in response to their child's vaccination.

A systematic review of varicella seroprevalence in European countries before universal childhood immunization: deriving incidence from seroprevalence data

Surveillance systems for varicella in Europe are highly heterogeneous or completely absent. We estimated the varicella incidence based on seroprevalence data, as these data are largely available and not biased by under-reporting or underascertainment. We conducted a systematic literature search for varicella serological data in Europe prior to introduction of universal varicella immunization. Age-specific serological data were pooled by country and serological profiles estimated using the catalytic model with piecewise constant force of infection. From the estimated profiles, we derived the annual incidence of varicella infection (/100·000) for six age groups (<5, 5–9, 10–14, 15–19, 20–39 and 40–65 years). In total, 43 studies from 16 countries were identified. By the age of 15 years, over 90% of the population has been infected by varicella in all countries except for Greece (86·6%) and Italy (85·3%). Substantial variability across countries exists in the age-specific annual incidence of varicella primary infection among the <5 years old (from 7052 to 16 122 per 100 000) and 5–9 years old (from 3292 to 11 798 per 100 000). The apparent validity and robustness of our estimates highlight the importance of serological data for the characterization of varicella epidemiology, even in the absence of sampling or assay standardization.

Estimation of the burden of varicella in Europe before the introduction of universal childhood immunization

BACKGROUND

Varicella is generally considered a mild disease. Disease burden is not well known and country-level estimation is challenging. As varicella disease is not notifiable, notification criteria and rates vary between countries. In general, existing surveillance systems do not capture cases that do not seek medical care, and most are affected by underreporting and underascertainment. We aimed to estimate the overall varicella disease burden in Europe to provide critical information to support decision-making regarding varicella vaccination.

METHODS

We conducted a systematic literature review to identify all available epidemiological data on varicella IgG antibody seroprevalence, primary care and hospitalisation incidence, and mortality. We then developed methods to estimate age-specific varicella incidence and annual number of cases by different levels of severity (cases in the community, health care seekers in primary care and hospitals, and deaths) for all countries belonging to the European Medicines Agency (EMA) region and Switzerland.

RESULTS

In the absence of universal varicella immunization, the burden of varicella would be substantial with a total of 5.5 million (95% CI: 4.7-6.4) varicella cases occurring annually across Europe. Variation exists between countries but overall the majority of cases (3 million; 95% CI: 2.7-3.3) would occur in children <5 years. Annually, 3-3.9 million patients would consult a primary care physician, 18,200-23,500 patients would be hospitalised, and 80 varicella-related deaths would occur (95% CI: 19-822).

CONCLUSIONS

Varicella disease burden is substantial. Most cases occur in children <5 years old but adults require hospitalisation more often and are at higher risk of death. This information should be considered when planning and evaluating varicella control strategies. A better understanding of the driving factors of country-specific differences in varicella transmission and health care utilization is needed. Improving and standardizing varicella surveillance in Europe, as initiated by the European Centre for Disease Prevention and Control (ECDC), is important to improve data quality to facilitate inter-country comparison.

Preparing to introduce the varicella vaccine into the Italian immunisation programme: varicella-related hospitalisations in Tuscany, 2004-2012

A universal immunisation programme against varicella in the form of the measles-mumps-rubella-varicella (MMRV) vaccine for toddlers aged 13-15 months was introduced in Tuscany in July 2008. An assessment of the impact of this programme on varicella-related hospitalisations 4 years after its introduction could further support its adoption at a national level. The hospitalisation data were analysed in two periods: pre-vaccination (2004-2007) and vaccination period (2009-2012). The high coverage of the vaccines (84% in 2012) resulted in a significant decline in notifications, from 33,114 (2004-2007) to 13,184 cases (2009-2012), and also of hospitalisations, from 584 (pre-vaccination period) to 325 (vaccination period). The hospitalisation rate was 4.1 per 100,000 (95% confidence intervals (CI): 3.4-4.7) before the introduction of vaccination, which dropped to 2.2 per 100,000 (95% CI: 1.7-2.7) in the vaccination period (hospitalisation risk ratios: 0.54; 95% CI:  0.472-0.619). The reduction was most significant in the youngest age groups. The introduction of universal vaccination has already led to a significant decline in hospitalisations due to varicella after just 4 years of implementation. Hospitalisation rates fell noticeably among younger individuals involved in the vaccination programme. The decrease in hospitalisation rate in the older age groups suggests a possible indirect protection.

Microbiology laboratory and the management of mother-child varicella-zoster virus infection

Varicella-zoster virus, which is responsible for varicella (chickenpox) and herpes zoster (shingles), is ubiquitous and causes an acute infection among children, especially those aged less than six years. As 90% of adults have had varicella in childhood, it is unusual to encounter an infected pregnant woman but, if the disease does appear, it can lead to complications for both the mother and fetus or newborn. The major maternal complications include pneumonia, which can lead to death if not treated. If the virus passes to the fetus, congenital varicella syndrome, neonatal varicella (particularly serious if maternal rash appears in the days immediately before or after childbirth) or herpes zoster in the early years of life may occur depending on the time of infection. A Microbiology laboratory can help in the diagnosis and management of mother-child infection at four main times: (1) when a pregnant woman has been exposed to varicella or herpes zoster, a prompt search for specific antibodies can determine whether she is susceptible to, or protected against infection; (2) when a pregnant woman develops clinical symptoms consistent with varicella, the diagnosis is usually clinical, but a laboratory can be crucial if the symptoms are doubtful or otherwise unclear (atypical patterns in immunocompromised subjects, patients with post-vaccination varicella, or subjects who have received immunoglobulins), or if there is a need for a differential diagnosis between varicella and other types of dermatoses with vesicle formation; (3) when a prenatal diagnosis of uterine infection is required in order to detect cases of congenital varicella syndrome after the onset of varicella in the mother; and (4) when the baby is born and it is necessary to confirm a diagnosis of varicella (and its complications), make a differential diagnosis between varicella and other diseases with similar symptoms, or confirm a causal relationship between maternal varicella and malformations in a newborn.

Factors influencing completion of multi-dose vaccine schedules in adolescents: a systematic review

BACKGROUND

Completion of multiple dose vaccine schedules is crucial to ensure a protective immune response, and maximise vaccine cost-effectiveness. While barriers and facilitators to vaccine uptake have recently been reviewed, there is no comprehensive review of factors influencing subsequent adherence or completion, which is key to achieving vaccine effectiveness. This study identifies and summarises the literature on factors affecting completion of multi-dose vaccine schedules by adolescents.

METHODS

Ten online databases and four websites were searched (February 2014). Studies with analysis of factors predicting completion of multi-dose vaccines were included. Study participants within 9-19 years of age were included in the review. The defined outcome was completion of the vaccine series within 1 year among those who received the first dose.

RESULTS

Overall, 6159 abstracts were screened, and 502 full texts were reviewed. Sixty one studies were eligible for this review. All except two were set in high-income countries. Included studies evaluated human papillomavirus vaccine, hepatitis A, hepatitis B, and varicella vaccines. Reported vaccine completion rates, among those who initiated vaccination, ranged from 27% to over 90%. Minority racial or ethnic groups and inadequate health insurance coverage were risk factors for low completion, irrespective of initiation rates. Parental healthcare seeking behaviour was positively associated with completion. Vaccine delivery in schools was associated with higher completion than delivery in the community or health facilities. Gender, prior healthcare use and socio-economic status rarely remained significant risks or protective factors in multivariate analysis.

CONCLUSIONS

Almost all studies investigating factors affecting completion have been carried out in developed countries and investigate a limited range of variables. Increased understanding of barriers to completion in adolescents will be invaluable to future new vaccine introductions and the further development of an adolescent health platform. PROSPERO reg# CRD42014006765.

Varicella in Europe-A review of the epidemiology and experience with vaccination

There is no consensus as regards the European varicella immunisation policy; some countries have introduced varicella vaccination in their routine childhood immunisation programs whereas others have decided against or are debating. With the aim of providing an overview of the epidemiology of varicella in Europe and addressing the different strategies and the experiences so far, we performed a review of epidemiological studies done in Europe from 2004 to 2014. Varicella is mainly a disease of childhood, but sero-epidemiological studies show regional differences in the proportion of susceptible adults. Hospitalisation due to varicella is not common, but complications and hospitalisation mainly affect previously healthy children, which underlines the importance of not dismissing varicella as a disease of little importance. The experience with universal vaccination in Europe shows that vaccination leads to a rapid reduction of disease incidence. Vaccine effectiveness is high and a protective herd effect is obtained. Experience with vaccination in Europe has not been long enough, though, to draw conclusions on benefits and drawbacks with vaccination as well as the capacity for national programs in Europe to maintain a sufficiently high coverage to prevent a change in age group distribution to older children and young adults or on the impact that varicella immunisation may have on the epidemiology of shingles.

Burden of varicella in Italy, 2001-2010: analysis of data from multiple sources and assessment of universal vaccination impact in three pilot regions

Varicella represents the most widespread vaccine-preventable childhood infectious disease in Italy. The purpose of this retrospective study was to assess the burden of varicella in Italy and in three regions that first implemented universal varicella vaccination. Four data sources were analysed: statutory notification data, the National Hospital Discharge Database, mortality data, and the vaccination coverage reached in Sicilia, Veneto and Apulia. The incidence rates per 100,000 population were calculated using the Italian resident population provided by the Italian Institute of Statistics in 2001-2010. In 2001-2010, the mean annual incidence of notifications of varicella was 150.7 cases per 100,000 population, reaching 948.6 cases per 100,000 population in the paediatric age group. The annual incidence declined to 102.6 per 100,000 population in 2010. During the period considered, 20,295 hospitalizations for varicella were observed. The mean annual incidence was 3.4 per 100,000 population, reaching a minimum of 2.5 per 100,000 in 2009 and 2010. Of the hospitalizations, 68.4% occurred in the paediatric age group. The median length of hospital stay was 4 days. During 2001-2003 and 2006-2010, 33 deaths were reported. In the three regions considered, vaccination coverage increased steadily, reaching 81.5% in Sicily, 79.4% in Veneto and 75.6% in Apulia in 2010. During the same period, hospitalization and notification rates decreased significantly. This study demonstrated that varicella continues to represent a relevant health problem in Italy, especially in the paediatric age group. Data obtained from the three Italian regions that first introduced universal vaccination demonstrated that vaccination reduces the incidence of varicella and hospitalization rates.

The clinical and epidemiological evolution of varicella in Romania during 2004 and 2013

INTRODUCTION

Varicella, a vaccine preventable disease (VPD) is one of the most common communicable diseases in Romania. The objectives of our study were to describe the epidemiological evolution of varicella in Romania between 2004 and 2013 and the clinical characteristics of the cases admitted to NIID between 2011 and 2013.

MATERIALS AND METHODS

An epidemiological retrospective study was conducted by using the information reported quarterly by general practitioners and hospitals at the national level. There is no system for the surveillance of severe cases in Romania, so, to describe the clinical characteristics of varicella cases, a second retrospective study was developed, in which the patients hospitalized in the NIID, within the period 2011-2013, were included. Questionnaires were completed by using data from the clinical observation forms. Collected information included demographic, clinical and laboratory data, complications, date of onset and admission, length of stay, admission and discharge diagnosis. Data were processed and analyzed by using Microsoft Excel program.

RESULTS

A total of 504,844 cases were reported of at the national level between 2004 and 2013, with a mean incidence of 238.2/ 100,000 inhabitants. The most affected age group was 5-9 years old (incidence 1362.7/ 100,000 inhabitants). The study conducted in NIID, registered 353 patients hospitalized with varicella between 2011 and 2013. Most of the hospitalized cases (88.8%) were under 10 years old and many (72.6 %) attended a community. The majority of cases had rash (98.6%) and fever (79.9%). The main complications were pneumonia (46.2%), bacterial infection (16.1%) and encephalitis (2.5%).

DISCUSSIONS

Varicella is a very common disease in Romania, which may develop complications. A specific surveillance system should be introduced in order to provide accurate epidemiological, clinical and laboratory information to assess whether varicella is a public health problem in Romania and if the introduction of vaccination in NIP is recommended. However, given the large number of current cases in Romania, a solution may be a sentinel surveillance system type.

Sero-Prevalence of Antibodies against Varicella Zoster Virus in Children under Seven-Years Old in 2012 in Tehran, Iran

BACKGROUND

Varicella zoster virus (VZV) is a member of herpes family viruses, which causes varicella (chickenpox) after primary infection and herpes zoster (shingles) because of latent virus reactivation from dorsal root ganglia. Generally, prevalence of varicella antibodies increases with age. We aimed to compare the prevalence of anti-VZV antibody in children under seven years old, in order to obtain a preliminarily picture of general presence of these antibodies to design an immunization plan.

METHODS

In this cross-sectional study, performed from September 2011 to September 2012 in Tehran, Iran, 267 serum samples including sera from 7 month old infants, n= 87; 18 month old children, n= 86; and 6 year old children, n= 94 were assessed for the presence of specific IgG antibodies against VZV, using ELISA technique.

RESULTS

4.6% of 7 month, 12.8% of 18 month and 21.3% of 6-year-old children were seropositive. No relation was found between demographic variables (e.g. age and birth weight) and seropositivity in these age groups. VZV antibodies increased with age. Serum levels of varicella antibodies were elevated in 18 months old compared to 7 months old children, significantly (P < 0.001).

CONCLUSION

In view of the significant elevation of VZV antibodies in children from 7 months to 18 months of age and rate of seronegative children, our results support the necessity of varicella immunization between 7 and 18 months of age in order to prevent viral infection.

Impact of universal vaccination against varicella in Italy

In Italy, the introduction of Universal Varicella Vaccination (UVV) has been decided but postponed, as a national programme, until 2015, when data from Regions which have already implemented it will be available. Starting from 2003, eight Italian Regions (Basilicata, Calabria, Friuli Venezia Giulia, Apulia, Sardinia, Sicily, Tuscany and Veneto) have progressively introduced UVV, in their immunization programme, with different schedules in children aged 13-15 months and 5-6 years, currently a two-dose schedule is adopted by all Regions. In June 2013, an Interregional Group on Varicella Vaccination (IGVV) has been established in order to assess the effectiveness of varicella vaccination with standardized and shared tools. The aim of this study was to evaluate the impact of varicella vaccination on the incidence and hospitalizations due to varicella and its complications in the period 2003-2012 in order to support the Italian decision makers on the future national adoption. Preliminary data showed that a general reduction of incidence and hospitalization rates was observed in the study period, resulting in relevant savings for the National Health Service. Immunization coverage with first dose at 24 months of age was high in all Regions (84%-95%) in 2012. Adverse events due to varicella vaccines were rare and without permanent sequelae. Underreporting of varicella cases and delays in the administration of the first dose of varicella vaccines were the main critical issues. In conclusion, solid evidences in support of universal UVV arise from the experiences available today in Italy.

Effectiveness of vaccination against varicella in children under 5 years in Puglia, Italy 2006-2012

In Italy, between 2003 and 2010, 8/21 Regions recommended varicella routine vaccination (URV). The National Immunization Plan (PNPV) 2012-2014 scheduled the introduction of URV nationwide in 2015, following the results achieved by the eight Regions.   Puglia adopted varicella URV in 2006. This study describes epidemiology and costs of varicella in Puglia between 2003 and 2012. One-dose Vaccine Effectiveness (VE) against varicella of any severity and severe hospitalized cases in children was also evaluated. Vaccination coverage (VC) was estimated from the regional immunization registry. Incidence and hospitalization rates were calculated from computerised surveillance system for communicable diseases and hospital discharge registry (ICD9-CM codes: 052.x), respectively. URV impact was assessed by Incidence Rate Ratios (IIRs) and Hospitalization Risk Ratios (HRRs). Hospitalization costs were also evaluated. VE was estimated using the screening method, where PPV was VC in children aged &lt;72 months and PCV was the proportion of cases vaccinated among notified or hospitalized cases, respectively. One-dose VC in children aged ≤ 24 months increased from 49% in the birth cohort 2006 to 91.1% in the cohort 2010; 2-dose VC was 64.8% and 28.8% in the 2005 and 1997 cohort, respectively. Comparing pre and post-vaccination era, incidence declined from 122.5 ×100 000 in 2003-2005 to 13.7 in 2009-2012 (IRR = 0.11, 95% CI = 0.10-0.12), hospitalization rate from 3.9 ×100 000 to 1.1 (HRR = 0.29, 95% CI = 0.21-0.4), hospitalization costs from 319 000 Euros/year to 106 000. One-dose VE against varicella of any severity and severe hospitalized disease was 98.8% and 99%, respectively. Our findings strongly support varicella URV introduction into the Italian Essential Health Interventions, as scheduled by 2015.

A seroprevalence survey on varicella among adults in the vaccination era in Apulia (Italy)

In 2006, the Apulia Region (Italy) introduced universal routine vaccination (URV) against varicella disease. The coverage for one dose of varicella vaccine at 24 month of age reached 91.1% in 2010 birth-cohort. Vaccination coverage for the second dose at 5-6 years was 64.8% for the cohort 2005, and 28.8% for adolescents born in 1997. The aim of the present study is to evaluate the pattern of immunity/susceptibility to varicella in Apulian adults by a seroprevalence survey carried out 6 years after the introduction of URV. The study was carried out from May 2011 to June 2012 among blood donors of the Department of Transfusion Medicine of Policlinico General Hospital in Bari. Subjects were enrolled by a convenience sample. For each enrolled patient we collected a sample of serum of 5 ml. Anti-VZV IgG in collected sera were analyzed by chemiluminescence (CLIA). We enrolled 1769 subject; 1365 (77.2%) were male with a mean age of 38.4 ± 11.7 years. 93% (95% CI=91.7-94.1) of enrolled subject presented a titre of anti-VZV IgG >164 mIU/mL. GMT of anti-VZV IgG titre was 1063.4 mIU/ml and no difference was observed between different age group. According to our data, URV did not seem to have any impact on susceptibility among adults and in particular we did not note any cluster of susceptible subjects among young adults. Also in the vaccination era, we did not note that the average age of infection shifts among adults and then we could exclude an increase of case of complicated varicella related to the URV.

Varicella vaccine uptake and associated factors in children in Hong Kong

Varicella is a common and highly contagious childhood disease which impacts the public worldwide. Hong Kong children can only be vaccinated against the disease in private practice. The varicella vaccination rate of local children in preschool is uncertain. Therefore a cross-sectional kindergarten-based parent-administered questionnaire survey was conducted in Hong Kong during 2012. Twelve kindergartens were randomly selected from a complete school list from the Education Bureau of Hong Kong. In total, 1285/1538 (83·6%) parents consented to join the study and completed the questionnaires. The overall varicella infection rate was 19·5% and the uptake of varicella vaccination rate was 57·6%. Barriers against varicella vaccination were mostly due to parental uncertainties about the effectiveness of vaccine, lack of recommendations from doctors or government, and adverse side-effects of the vaccine. The government and healthcare professional bodies are strongly recommended to further enhance health education among healthcare professionals, encouraging their active promotion of varicella vaccination for their patients. Furthermore, health education through various stakeholders is crucial to enhance parental awareness of varicella, as well as the effectiveness and safety of varicella vaccine.

Clinical and molecular aspects of the live attenuated Oka varicella vaccine

VZV is a ubiquitous member of the Herpesviridae family that causes varicella (chicken pox) and herpes zoster (shingles). Both manifestations can cause great morbidity and mortality and are therefore of significant economic burden. The introduction of varicella vaccination as part of childhood immunization programs has resulted in a remarkable decline in varicella incidence, and associated hospitalizations and deaths, particularly in the USA. The vaccine preparation, vOka, is a live attenuated virus produced by serial passage of a wild-type clinical isolate termed pOka in human and guinea pig cell lines. Although vOka is clinically attenuated, it can cause mild varicella, establish latency, and reactivate to cause herpes zoster. Sequence analysis has shown that vOka differs from pOka by at least 42 loci; however, not all genomes possess the novel vOka change at all positions, creating a heterogeneous population of genetically distinct haplotypes. This, together with the extreme cell-associated nature of VZV replication in cell culture and the lack of an animal model, in which the complete VZV life cycle can be replicated, has limited studies into the molecular basis for vOka attenuation. Comparative studies of vOka with pOka replication in T cells, dorsal root ganglia, and skin indicate that attenuation likely involves multiple mutations within ORF 62 and several other genes. This article presents an overview of the clinical aspects of the vaccine and current progress on understanding the molecular mechanisms that account for the clinical phenotype of reduced virulence.

Impact of universal vaccination on the epidemiology of varicella in Veneto, Italy

In 2005, universal varicella vaccination was introduced in the Veneto region, Italy. We examined trends in varicella incidence and hospitalization rates before and after vaccine introduction, and applied statistical models to assess vaccine effectiveness. Varicella incidence rates for 2000-2008 were calculated from the mandatory regional surveillance data and from a special surveillance system based on reports from a sample of family pediatricians that during the study period followed more than 40,000 children. To evaluate hospital admission rates, we analyzed the regional hospital discharge registry. The vaccine coverage rate was 6.8% in the 2004 birth-cohort and 78.6% in the 2008 cohort. Varicella incidence in 0-14 year-olds was 6136.8/100,000 person-years in 2000 and 4004.8 in 2008; hospitalization rates were 18.7 and 8.4. Incidence rates significantly decreased 2.5 years after beginning the universal vaccination, while hospitalization rates showed a significant decrease one year earlier. There was a remarkable decline of both varicella incidence and hospitalizations especially in 1-4 year-old children. This study confirms the positive impact of universal vaccination.

Varicella vaccination coverage in Bavaria (Germany) after general vaccine recommendation in 2004

Since 2004, general varicella vaccination has been recommended for all children 11-14 months of age in Germany. The objective of this study was to examine vaccination coverage in children and factors associated with parental acceptance during the first years after recommendation. In a regional surveillance area, cross-sectional parent surveys were conducted in 2006, 2007 and 2008 in random samples (n=600) of children aged 18-36 months; data were obtained for 372, 364 and 352 children, respectively. Parents were questioned on their child's varicella disease history, and on varicella vaccination status as recorded in the child's vaccination booklet. Overall coverage increased from 38% in 2006 to 51% in 2007 and stagnated at 53% in 2008; in susceptible children (without previous varicella disease until vaccination or time of survey) coverage was 42%, 61% and 59%, respectively. Recommendation by the paediatrician as reported by the parents increased from 48% (2006) to 57% (2007) and 60% (2008), and was the main independent factor associated with parental acceptance. In 32-35% of unvaccinated children parents had not yet decided whether to vaccinate against varicella. Additional programmes targeting paediatricians' and parents' acceptance of varicella vaccination are needed to achieve the WHO-defined goal of at least 85% coverage.

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.