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OBJECTIVE To elucidate the trend and clinical spectrum of virologically diagnosed varicella patients after implementation of universal vaccination as a national immunization program in Japan. PATIENTS AND METHODS Study subjects were patients suspected of varicella, less than 15 years of age, who visited 14 pediatric clinics in the Nagoya VZV Study Group from September 2015 to August 2019. Practitioners collected patient samples and information such as backgrounds, clinical symptoms, and previous immunization status. All patients were confirmed as having varicella based on molecular diagnostic assays. RESULTS Varicella zoster virus (VZV) DNA was detected in swab samples from 506 (83.1%) of the 609 suspected patients. The 455 varicella patients for whom vaccination status was available were divided into two groups: 180 universal vaccination targets and 275 non-targets. Numbers of monthly varicella patients decreased gradually during the observation period. In the 2016/17 season, the seasonal epidemic of varicella became undetectable in the universal vaccination target group, and starting in the 2017/18 season, it was obscured even in the non-target group. The median age of patients was significantly lower in the universal vaccination target group (3 years) than the non-target group (7 years) (P

Objective The aim of this study was to elucidate vaccine effectiveness (VE) during varicella outbreaks in schools and nurseries in Japan. Methods An outbreak was defined as emergence of three or more cases of varicella within 21 days at the same institute. Clinical information such as varicella vaccination status, and history of varicella was collected. If a child had varicella during the outbreak, information about absences, fever, and disease severity was collected. Results From September 2018 to January 2020, four outbreaks were reported around our institute from three elementary schools and one nursery. A total of 676 children were analyzed in this study. Seventy-six children (11.2%) were unvaccinated, 309 (45.7%) had received one dose of vaccine, and 291 (43.0%) had received two doses. Most children in Pre-K2 (1–2 years old) to Pre-K6 (5–6 years old), who were the targets of the national immunization schedule, received two doses. Meanwhile, most children older than third grade received single dose. Seventy-five children (11.1%) had varicella. Varicella prevalence from Pre-K5 to the third grade was greater than 10%. The adjusted VEs of single- and two-dose of varicella vaccine were 57.8% and 89.0%. The number of days absent was significantly longer in unvaccinated children than single-dose recipients (P = 0.0145). Unvaccinated children had significantly more severe skin eruptions than single-dose recipients (P = 0.0046) and two-dose recipients (P = 0.0258). Conclusions Although VEs of single-dose varicella vaccination during outbreaks was not high, the VE of two-dose vaccination was similar to that in a previously reported case-control study.

Background In South Korea, one-dose varicella vaccination was introduced to the National Immunization Program in 2005, but varicella outbreaks have continued to occur. Therefore, a two-dose vaccination strategy is considered. Methods We developed an age-structured deterministic compartment model using Korean population projection data. The impact of adding a second dose of varicella vaccine on varicella and herpes zoster (HZ) epidemiology was assessed under four different vaccine effectiveness (VE) scenarios (base, moderate, lowest, highest) and the optimal timing of the second vaccine dose (18 months, 4, 5, or 6 years of age) was examined over the period 2020–2065. Results A two-dose vaccination schedule reduced the cumulative varicella incidence by > 90% compared to no vaccination, regardless of the VE. The additional reduction attributable to a second dose compared to a single dose was greatest (82%) with the lowest VE scenario. A second dose at 6 years of age reduced the varicella incidence at a population level, whereas a second dose at 18 months of age reduced the varicella incidence primarily in the target birth cohorts. Routine vaccination at the age of 18 months with a catch-up vaccination of 6-year-olds was the optimal strategy for birth cohort and population-level control. HZ incidence continued to increase under no vaccination scenario, which represents the effect of aging population. Under a two-dose scenario, the additional increase in HZ incidence attributable to the reduced exogenous boosting was small relative to a one-dose scenario and a further reduction in HZ cases was observed. Conclusion A two-dose varicella vaccination schedule would significantly reduce varicella and HZ incidence in the long term. A second dose at the age of 18 months with a catch-up vaccination of 6-year-olds would be optimal for controlling varicella in South Korea.

The present study summarizes evidences of the impact that varicella vaccination (VV) introduction and coverage can have on varicella attributable hospitalization rates.A retrospective observational study was carried out by considering hospital discharge records and VV coverage at 24 months collected from 2003 to 2018 by the Italian Ministry of Health. All hospitalizations records reporting an ICD-9 CM 052.X code as the principal diagnosis or any of the five secondary diagnoses were considered as related to varicella. The hospitalization rate reduction was evaluated by calculating average annual percent change (AAPC) through joint-point analysis.Hospitalization rates showed a decreasing trend by age: children1 year of age were the most affected group in each Italian administrative region (42.5/100,000 per year), whereas lower incidence rates were found in older age groups (23.8/100,000 in 1-5 years old and4.0/100,000 in the following groups). Varicella hospitalization rates decreased significantly after the introduction of VV (3.4 vs. 2.7 per 100,000; p 0.001). During the first five years after the introduction of vaccination, hospitalization rates showed a statistically significant decrease especially among infants1 year of age (AAPC -35.0%; p 0.001) and 1-5 years old (AAPC -35.2%; p 0.01). Total percentage changes were -80.0% and -86.7%, in the age class1 year old and 1-5 years old, respectively.All the previously reported findings confirm that hospitalization rates are strictly related to both the vaccination coverage and the number of years since the introduction of the vaccination. VV confirms to be an important step in public health strategies and the introduction of universal vaccination, with high vaccination coverage, should be considered as an extremely powerful tool to reduce the risk of complications.

Varicella vaccination is important in prevention of childhood infection. Aim of this cross-sectional study was to survey attitudes and determinants of support or refusal of varicella vaccination in parents and in paediatric healthcare professionals, mainly health visitors in Hungary prior to the introduction of this vaccine in National Immunization Program in 2019.Between October 2018 and February 2019, 1042 parents and 198 healthcare professionals completed a self-administered anonymous questionnaire regarding sociodemographic background, knowledge and attitudes towards varicella vaccination, and reasons for non-vaccination.From the participating parents 53.3% have vaccinated at least one of their children. Vaccination rate was significantly higher in families with3 children, living in the capital, among those who have seen complications of varicella and among parents with university degree. Most important positive determinant was recommendation of the vaccine by healthcare professionals: 77.8% of parents accepted vaccination when recommended by the paediatrician, despite the cost of the vaccine, whereas only 17.3% of parents vaccinated their children when the vaccine was not recommended by paediatrician. Most important reasons for non-vaccination was finding the vaccine unnecessary, concerns regarding side effects, and not believing in the vaccine's effectiveness. Among paediatric healthcare professionals, support rate of universal varicella vaccination was 76.3%. Support rate was higher among those who have seen complications of varicella more often and those who consider varicella a severe infection. Reasons of professionals who do not support universal varicella vaccination were similar to those of vaccine hesitant parents. Practice of intentional exposure of non-immune child to infected ones still exist.Educational programs are needed for parents and health visitors to address concerns regarding vaccination. Paediatricians are the most trusted source of information for parents hence they have a significant responsibility and parents likely follow their recommendations.

Routine childhood immunization using two doses of the varicella vaccine was introduced in Japan in October 2014. In this study, we analyzed the data extracted from national varicella surveillance, including pediatric sentinel surveillance from 2000 to 2017 and hospitalized varicella surveillance from the 38th week of 2014 to the 37th week of 2017. Compared with the 2000-2011 baseline data, the number of varicella cases per sentinel decreased substantially by 76.6% overall and by 88.2% among children aged 1-4 years in 2017. Of 997 hospitalized patients, we found a decreasing trend in the number of cases among children aged5 years. We also found a decreasing trend in the number of cases with complications among children aged 1-4 years. Data on the self-reported transmission sites in 35.5% (354/997) of the hospitalized varicella patients showed that transmission of varicella zoster virus (VZV) occurred frequently in household, at school for young children, in the workplace for adults, and at hospital for all age groups. Data from 29.0% (289/997) of the hospitalized patients with a self-reported source of infection showed that transmission of VZV occurred from a patient with herpes zoster (HZ) in 30.4% (88/289) of cases. Our data demonstrate a substantial decrease in the number of varicella cases in young children following introduction of routine childhood vaccination program with two-dose varicella vaccination in Japan. These data highlight the unique aspects of transmission sites across age groups and the important role of HZ cases in disease circulation.

1-Dose varicella vaccination was recommended for children in Beijing before November 2012. To further control school-based outbreaks and decrease incidence, a 2-dose vaccination was implemented in 2013. We described the varicella epidemiology and assessed impact of the 2-dose vaccination in Haidian district, Beijing, 2007-2015.We examined the estimated incidence and disease characteristics of varicella during 2007-2015 and obtained the 1-dose vaccination coverage for children born during 2005-2013. Number of vaccine doses given was used to indirectly reflect the second-dose vaccination coverage. Overall and age-specific estimated incidences were compared between 2007-2012 and 2013-2015.A total of 23,497 cases were reported during 2007-2015. Of the 23,497 cases, 13,440 (57.20%) were male, and 68.40% were20years of age and 70.02% were students and children in kindergarten. The estimated incidence increased from 82 cases per 100,000 population in 2007 to 104 in 2011, before substantially decreasing from 86 in 2012 to 56 in 2015. The median age increased from 14years in 2007 to 18years in 2015. The 1-dose varicella coverage for children at ≥2years of age gradually increased from 74.21% in 2007 to 90.06% in 2015. Compared with 2007-2012, two-fold average vaccine doses were given during 2013-2015, and the overall estimated incidence declined by 34.4%, particularly in children aged 5-9years, with a significantly declined trend in children aged 1-9years and older adolescents aged 15-19years and non-significantly declined trend in adults aged ≥20years, but a significant increasing trend in infants.The overall incidence of varicella has decreased substantially in Haidian district since 2013, with largest decline in children aged 5-9years. The 2-dose varicella vaccination might not lead to increase in incidence in adults. Long-term surveillance is needed to fully evaluate the long-term impact of the 2-dose varicella vaccination.

Objective To evaluate the long-term safety and efficacy of varicella vaccination in children with juvenile idiopathic arthritis (JIA) treated with biologics. Methods We performed a prospective study with long term follow up. Six patients with JIA treated with biologics, received 2 doses of varicella vaccine. Before vaccination, JIA was stable on therapy and peripheral blood lymphocyte populations were within normal limits. After vaccination, children were followed for disease activity, infections and production of protective antibodies. Results There were no serious side effects after vaccination and no varicella infection. Disease activity remained stable. Five patients (83%) produced protective antibodies against varicella virus 6 weeks after the second vaccination. One patient with low level of protective antibodies got mild varicella infection 4 months after the second vaccination. Conclusion Varicella vaccination appears to be safe in our group of six JIA patients treated with biologics. Vaccination does not always protect against varicella infection.

Varicella vaccines available in Spain were marketed in 1998 and 2003 for non-routine use. Since 2006 some regions included universal varicella vaccination in their regional routine vaccination programs at 15-18 months of age. Regions without universal vaccination in toddlers, but instead with the strategy of vaccinating susceptible adolescents, reached different varicella vaccination coverage through private market. This study shows the correlation between severe varicella zoster virus infections requiring hospitalization and the varicella vaccination coverage by region. A total of 3009 hospital discharges related to varicella were reported in 2009-2010. The overall annual rate of hospitalization was 3.27 cases per 100,000. In children younger than 5 years old varicella hospitalization rate was 30.73 cases per 100,000. Varicella related hospitalizations were significantly lower in the regions with universal vaccination. In those regions without universal vaccination at 15-18 months of age, those with higher coverage in private market showed lower hospitalization rates.

The Brazilian childhood National Immunization Program (NIP) introduced live and attenuated varicella vaccination in a single dose, combined as tetraviral vaccine, at 15 months of age in the whole country, during September to December of 2013. The aim of this study was to report trends in incidence of childhood hospital admissions related to varicella and zoster in Brazil from 2003 to 2016, including the first three years after vaccine introduction.The number and incidence of hospital admission in patients aged less than 20 years in Brazilian public health system with an admission diagnosis of varicella and zoster from 2003 to 2016 were analyzed and pre (2003-2013) and post-vaccination periods (2014-2016) were compared. The data were obtained from DATASUS, a Brazilian government's open-access public health database system, and analyzed adjusting for secular trend and seasonality if a statistically significant change was found.During the study period, 69,791 admissions due to varicella and herpes zoster occurred in the children younger than 20 years. After adjusting for seasonality, the incidence of hospitalizations decreased from 27.33 to 14.33 per 100000 per year, which corresponds to a reduction of 47.6% (95% confidence interval 18.19-77.04%, p 0.001) in the vaccinated age group (1-4 years) in 2014-2016 compared to pre-vaccination period. The changes were not significant in the unvaccinated age groups.The hospitalizations due to varicella and herpes zoster were decreased by half early after the introduction of a single dose of tetraviral vaccine in NIP in the vaccinated children. Further studies may assess duration and intensity of this effect, as well as the indirect effect in the unvaccinated age groups.

Purpose: A universal publicly funded chickenpox vaccination program was implemented in Alberta in 2002. We examine the epidemiology of medically attended shingles in Alberta from 1994 to 2010. Methods: Incident shingles cases (earliest health service utilizations for ICD-9 053 or ICD-10-CA B02) and their co-morbid conditions for the 12 months prior to shingles diagnosis were identified from the records of Alberta's universal, publicly funded health-care insurance system for 1994–2010. Shingles diagnostic codes at least 180 days after the first were classified as recurrent episodes. Denominators for rates were estimated using mid-year population estimates from the Alberta Health Care Insurance Plan Registry. Annual age- and sex-specific rates were estimated. We estimated the proportion of all cases that were hospitalized. We explored the pattern of rates for sex, age-group co-morbidity and year effects and their interactions. Results: Crude rates of shingles increased over the interval 1994–2010. Most persons had only a single episode of shingles; 4% of cases were hospitalized. Shingles rates were higher among females than males. While only 2% of shingles cases had one or more co-morbidities, this proportion was also higher for females than males. Prior to 2002, all age groups of both sexes experienced increasing annual rates of shingles. However, there was a sharp decline in the rate of shingles for both females and males under the age of 10 years for 2002–2010, the period in which there was publicly funded chickenpox vaccination. Conclusion: The declining rates of shingles among persons under the age of 10 years are consistent with an impact of the chickenpox vaccination program. The trend of increasing rates of shingles among older persons began prior to implementation of vaccination.

Characteristics of varicella-related hospitalizations in the mature varicella vaccination era, including the proportion vaccinated and the severity of disease, are not well described. We present the vaccination status, severity and reasons for hospitalization of the hospitalized varicella cases reported to the Los Angeles County Health Department from 2003 to 2011, the period which includes the last 4 years of the mature one-dose program and the first 5 years after introduction of the routine two-dose program. A total of 158 hospitalized varicella cases were reported overall, of which 52.5% were potentially preventable and eligible for vaccination, 41.8% were not eligible for vaccination, and 5.7% were vaccinated. Most hospitalizations (72.2%) occurred among healthy persons, 54.4% occurred among persons ≥20 years of age, and 3.8% of hospitalizations resulted in death. Our data suggest that as many as half of the hospitalized varicella cases, including half of the deaths, may have been preventable given that they occurred in persons who were eligible for vaccination. More complete implementation of the routine varicella vaccination program could further reduce the disease burden of severe varicella.

Highlights • Chickenpox history may enable cost-effective vaccination of susceptible individuals. • We tested the validity of reported chickenpox history in adolescents. • Vaccine would be wasted in most adolescents with a negative or uncertain history. • 6–9% of those with a positive chickenpox history would remain susceptible. • These data are needed to inform cost-effectiveness of proposed vaccine programmes., Introduction In the UK, primary varicella is usually a mild infection in children, but can cause serious illness in susceptible pregnant women and adults. The UK Joint Committee on Vaccination and Immunisation is considering an adolescent varicella vaccination programme. Cost-effectiveness depends upon identifying susceptibles and minimising vaccine wastage, and chickenpox history is one method to screen for eligibility. To inform this approach, we estimated the proportion of adolescents with varicella antibodies by reported chickenpox history. Methods Recruitment occurred through secondary schools in England from February to September 2012. Parents were asked about their child's history of chickenpox, explicitly setting the context in terms of the implications for vaccination. 247 adolescents, whose parents reported positive (120), negative (77) or uncertain (50) chickenpox history provided oral fluid for varicella zoster virus-specific immunoglobulin-G (VZV-IgG) testing. Results 109 (90.8% [85.6–96.0%]) adolescents with a positive chickenpox history, 52 (67.5% [57.0–78.1%]) with a negative history and 42 (84.0% [73.7–94.3%]) with an uncertain history had VZV-IgG suggesting prior infection. Combining negative and uncertain histories, 74% had VZV-IgG (best-case). When discounting low total-IgG samples and counting equivocals as positive (worst-case), 84% had VZV-IgG. We also modelled outcomes by varying the negative predictive value (NPV) for the antibody assay, and found 74–87% under the best-case and 84–92% under the worst-case scenario would receive vaccine unnecessarily as NPV falls to 50%. Conclusion Reported chickenpox history discriminates between varicella immunity and susceptibility in adolescents, but significant vaccine wastage would occur if this approach alone were used to determine vaccine eligibility. A small but important proportion of those with positive chickenpox history would remain susceptible. These data are needed to determine whether reported history, with or without oral fluid testing in those with negative and uncertain history, is sufficiently discriminatory to underpin a cost-effective adolescent varicella vaccination programme.

Germany introduced routine varicella (V) vaccination in 2004. Due to a slightly increased risk of febrile convulsions after first-dose application of combined measles-mumps-rubella-varicella (MMRV) vaccine separate first-dose vaccinations with MMR and monovalent V vaccine were recommended in September 2011.We compared V and MMR vaccinations in paediatric practices from two surveillance regions (Munich and Würzburg) one year before and after the change in the recommendation.A total of 1405/326 monthly reports were provided by a monthly average of 79/14 practices participating in Munich/Würzburg. V first-dose vaccinations (monovalent V or MMRV vaccine) declined by 12% in Munich (from 10.1 to 8.9 vaccinations per month and practice; p0.005) and by 4% in Würzburg (from 9.9 to 9.5; p=0.620), respectively. First-dose vaccinations for MMR (MMR or MMRV vaccine) did not change significantly in both regions.Acceptance of V vaccination depends in part on the use of combination vaccine.

Varicella vaccines available in Spain were marketed in 1998 and 2003 for non-routine use. Since 2006 some regions decided to include varicella vaccination in their regional routine vaccination programmes at 15-18 months of age. Other regions chose the strategy of vaccinating susceptible adolescents. This study shows the trends in severe varicella zoster virus infections through the analysis of the hospital discharges related to varicella and herpes zoster in the general population from 2005 to 2010 in Spain. A total of 11,125 hospital discharges related to varicella and 27,736 related to herpes zoster were reported during the study period. The overall annual rate of hospitalization was 4.14 cases per 100,000 for varicella and 10.33 cases per 100,000 for herpes zoster. In children younger than 5 years old varicella hospitalization rate significantly decreased from 46.77 in 2005 to 26.55 per 100,000 in 2010. The hospitalization rate related to herpes zoster slightly increased from 9.71 in 2005 to 10.90 per 100,000 in 2010. This increase was mainly due to the significant increase occurring in the >84 age group, from 69.55 to 97.68 per 100,000. When gathering for regions taking into account varicella vaccine strategy, varicella related hospitalizations decreased significantly more in those regions which included the vaccine at 15-18 months of age as a routine vaccine comparing with those vaccinating at 10-14 years old. No significant differences were found in herpes zoster hospitalization rates regarding the varicella vaccination strategy among regions. Severe varicella infections decreased after implementation of varicella vaccination in Spain. This decrease was significantly higher in regions including the vaccine at 15-18 months of age compared with those vaccinating susceptible adolescents.

Background In November 2005, Australia introduced a publicly funded single dose of varicella vaccine for children aged 18-months. We describe the impact of this program on varicella hospitalisations in Queensland and provide the first assessment of single-dose varicella vaccine effectiveness in Australia since the program commenced. Methods Age-standardised varicella hospitalisation rates were calculated for 2000–2014 and pre- and post-public funding period rates compared. Case-control studies were conducted to investigate the association between vaccine receipt and both varicella hospitalisations and uncomplicated varicella emergency department presentations. Cases were matched to controls from a population-based register by date of birth and state of residence. Vaccine effectiveness was calculated as (1 – odds ratio) × 100%. Results Compared to the pre-funded period (2000–2003), age-standardised varicella hospitalisation rates declined by more than 70% in 2011–2014 with varicella principal diagnosis rates declining from 5.7 to 1.6 per 100,000 population per year. Varicella vaccine effectiveness at preventing hospitalisation with a principal diagnosis of varicella among children aged 19-months to 6-years was 81.9% (95% confidence interval: 61.8–91.4%), while for emergency department presentations among children aged 19-months to 8-years it was 57.9% (95% confidence interval: 48.5–65.5%). Conclusions In Australia, the single-dose varicella vaccination program has substantially reduced varicella morbidity. The single-dose varicella vaccine schedule is moderately-to-highly effective against hospitalisation, but appears less effective against emergency department presentations.

Varicella vaccines have been available for private purchase in Canada since 1998. Ontario introduced publicly funded varicella vaccination in 2004. We assessed the effects of private availability of varicella vaccines and subsequent implementation of a publicly funded vaccination program on varicella-related hospitalizations, emergency department (ED) use, and visits to physicians' offices in Ontario. Rates of hospitalizations, ED use, and office visits decreased 53% (95% CI, 48-58%), 43% (95% CI, 41-44%), and 45% (95% CI, 44-45%) after publicly funded vaccination, compared to only 9% (95% CI, 4-14%), 23% (95% CI, 22-24%), and 29% (95% CI, 28-29%) after private availability. Varicella vaccination is effective at reducing varicella-related health care use, with benefits extending beyond those who receive the vaccine. Publicly funded vaccination programs may be more effective than private vaccine availability.

The impact of a varicella vaccination program on disease in a large HMO population during 1996-1999 was assessed by multiple cross-sectional analyses of automated database records of vaccinations and varicella diagnoses for children (0-18 years). The cumulative proportion of the population vaccinated reached 73% among 2-year-olds, and 22% overall. An overall 49.7% reduction in varicella incidence was estimated to be attributable to an 18.5% point increase in the proportion of the population vaccinated.

Active surveillance for herpes zoster (HZ) was conducted for 2 years (2000–2001) in the Antelope Valley community of 312,000 residents among 290 public and private schools, daycares, and healthcare providers. The true ascertainment-adjusted HZ incidence rate is 307 per 100,000 person-years and 138 per 100,000 person-years among children

Accompanying varicella vaccination in children in Germany recommended with one (2004) and two (2009) doses, sentinel surveillance of varicella with a sample (n∼900) of private physicians was established in 2005. Physicians reported monthly aggregated data on all varicella cases and case-based on vaccinated patients, of whom skin lesion samples were laboratory investigated to identify varicella-zoster virus (VZV). We analyzed the impact of vaccination frequency on the number of cases and on laboratory results within the sentinel.Swabs were obtained with a Teflon tip and sent together with a case-based questionnaire to the reference laboratory. VZV wild-type and vaccine-type was identified by polymerase chain-reaction (PCR) and pyrosequencing methods. Case-based data and laboratory results were analyzed descriptively.From April 2005 to March 2014, of all monthly reported cases (n=111,456) 4789 were vaccinated and eligible for further analysis. No differences were found between laboratory investigated and not investigated cases (1017 vs. 3772) except that the proportion of cases vaccinated twice was higher in lab-cases (29.4% vs. 16.1%). PCR remained negative in 69.6% (197/283) of breakthrough-cases vaccinated twice, in comparison to 22.7% (147/649) breakthrough-cases vaccinated once. VZV was confirmed in 500 (81) patients with breakthrough varicella after one (two) vaccination(s); identification of VZV wild-type, vaccine-type, or no further differentiation was possible in 485 (72), 5 (6), and 10 (3) cases, respectively.Varicella breakthrough disease is rare in Germany and suspected clinical cases require laboratory confirmation. The lower confirmation rate of VZV after two vaccine doses suggests a better protection compared to one dose.

In 1974, a live varicella vaccine (Oka strain) was developed in Japan for the prevention of varicella. It has been commercially available since 1987 for the voluntary vaccination program, in which children over the age of 1 year with no history of previous varicella infection receive a single dose. From before approval up to the present, we have been carrying out long-term studies in healthy children at a regional hospital to assess the immunogenicity, safety, and efficacy of the varicella vaccine. This vaccine is very safe, and serious adverse reactions have not been observed since the year 2000 when it changed gelatin-free. In the past three studies, seroconversion was detected in around 95% of subjects by the immune adherence hemagglutination (IAHA) test, and this high rate was considered to indicate good immunogenicity. Breakthrough varicella is observed in approximately 20–30% of children who receive a single dose of the vaccine, but most cases are mild. Although recent vaccination has generally been effective, the IAHA test has shown that immunogenicity is somewhat lower than was previously demonstrated. The sensitivity of the IAHA test has been shown to be adequate when compared with the neutralization test, so the current testing system is sufficient for the maintenance of immunity levels. An additional vaccination increased the IAHA antibody level in subjects who failed to seroconvert after a single dose vaccination. According to another clinical study, additional varicella vaccination at 3–5 years after the initial vaccination achieved stronger immunogenicity. Because it is administered as part of the voluntary vaccination program, the varicella vaccination coverage rate has remained low in Japan, with no sign of a decrease in the number of varicella patients. We consider that implementation of routine varicella vaccination program based on the Preventive Vaccination Law would be the most effective approach for improvement of the coverage rate. Along with this, introduction of a two-dose schedule would also be desirable. In addition to decreasing the prevalence of characteristic breakthrough varicella infection, the vaccination coverage rate would also be expected to improve with a two-dose schedule due to an increase in opportunities for vaccination.

Background A second dose of varicella vaccine was recommended for U.S. children in 2006. We investigated a suspected varicella outbreak in School District X, Texas to determine 2-dose varicella vaccine effectiveness (VE). Methods A varicella case was defined as an illness with maculopapulovesicular rash without other explanation with onset during April 1–June 10, 2011, in a School District X student. We conducted a retrospective cohort in the two schools with the majority of cases. Lesion, saliva, and environmental specimens were collected for varicella-zoster virus (VZV) PCR testing. VE was calculated using historic attack rates among unvaccinated. Results In School District X, 82 varicella cases were reported, including 60 from Schools A and B. All cases were mild, with a median of 14 lesions. All 10 clinical specimens and 58 environmental samples tested negative for VZV. Two-dose varicella vaccination coverage was 66.4% in Schools A and B. Varicella VE in affected classrooms was 80.9% (95% CI: 67.2–88.9) among 1-dose vaccinees and 94.7% (95% CI: 89.2–97.4) among 2-dose vaccinees in School A, with a second dose incremental VE of 72.1% (95% CI: 39.0–87.3). Varicella VE among School B students did not differ significantly by dose (80.1% vs. 84.2% among 1-dose and 2-dose vaccinees, respectively). Conclusion Laboratory testing could not confirm varicella as the etiology of this outbreak; clinical and epidemiologic data suggests varicella as the likely cause. Better diagnostics are needed for diagnosis of varicella in vaccinated individuals so that appropriate outbreak control measures can be implemented.

We carried out a matched case-control study to analyze the possible association between exposure to the children and the risk of suffering herpes-zoster in adulthood. Cases of herpes zoster in immunocompetent healthy patients aged ≥ 25 years seen in the dermatology department of the Sagrado Corazon Hospital in 2007-2008 were matched with four controls. Data were analyzed using conditional logistic regression. 153 cases and 604 matched controls were included. Contacts with children were significantly associated with a reduction in the risk of suffering herpes zoster in adulthood (adjusted OR 0.56 [0.37-0.85]). Herpes-zoster vaccination in immunocompetent people aged ≥ 50 years could counteract the possible negative effects of mass varicella vaccination in childhood on the epidemiology of herpes zoster in adults.

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.

The aims of this study were to investigate the epidemiology of varicella and evaluate the effect of varicella vaccination on the burden of varicella in Taiwan. The outpatient and hospitalization claims made to the National Health Insurance (NHI) in public and private vaccination areas were compared during 2000-2002. In 2002, the outpatient visit rates for 1- to 5-year-old children in public vaccination areas were 66-78% lower than their counterparts in private vaccination areas. The reduction in outpatient visit rate was the greatest among preschool children. The reductions also occurred in every age group including infants and adults. This study showed significant evidence of vaccine impact with a marked decline in clinical cases in the short term.

A deterministic realistic age-structured model was used to predict the impact of vaccination on the incidence of varicella and zoster. Unit costs, estimated from literature, were applied to the predicted health outcomes. Various vaccination programs were investigated and a sensitivity analysis was performed. Assuming no impact of vaccination on zoster, varicella vaccination is estimated to cost 45,000 dollars, 51,000 dollars and 18,000 dollars per life-year gained from the health payer's perspective for infant, infant with catch-up campaign, and preteen programs, respectively. From the societal perspective, mass infant varicella vaccination was estimated to be highly cost saving in Canada. Importantly, infant varicella vaccination could result in a short- to medium-term increase of zoster incidence and thus cause vaccination to be highly cost-ineffective (118,000 dollars per life-year gained) under the health payer's perspective. From a health payer's perspective the preteen vaccination is the only strategy that is deemed cost-effective. The cost-effectiveness of infant vaccination rests heavily on the unknown relationship between varicella and zoster.