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In South Korea, the National Immunization Program has included one-dose varicella vaccination for 1-year-olds since 2005. This study examines the potential impact of introducing a two-dose varicella vaccination for children, along with zoster vaccination for adults, using either the zoster vaccine live (ZVL) or recombinant zoster vaccine (RZV). The investigation considered four strategies in a base case scenario. The first involved introducing zoster vaccination for 60-year-olds, with a 60 % coverage. The second strategy combined zoster vaccination with a second-dose varicella vaccination for 4-year-olds, with a 90 % coverage. An age-structured model spanning 50 years was employed, assuming a zoster vaccine catch-up campaign over the initial 5 years. Cost-effectiveness analyses were conducted, assessing incremental cost-effectiveness ratios (ICERs), incremental net monetary benefits (INMBs), and net loss under different ages at zoster vaccination (50, 60, 65, and 70 years) and varying willingness-to-pay (WTP) levels from ₩40 million ($34,998) to ₩84 million ($74,000). All strategies were cost-effective and significantly reduced herpes zoster (HZ) incidence, preventing approximately 3,077,000 to 7,609,000 cases, depending on the chosen strategy. The combined strategy prevented around 4,950,000 varicella and 653,000 HZ cases additionally. RZV outperformed ZVL by preventing twice as many HZ cases and offering greater QALY gains. However, ZVL was more cost-effective due to its lower cost. Probabilistic sensitivity analyses revealed that RZV became more cost-effective at higher WTP thresholds, exceeding ₩60.9 million ($53,193) in terms of ICER and ₩62.5 million ($54,591) for INMBs and net loss. The optimal age for zoster vaccination was 60 years concerning ICER but 50 years regarding INMB. Combining RZV with a two-dose varicella vaccination strategy reduced the disease burden and improved QALY more effectively, though ZVL remained more cost-effective at lower WTP levels. Decisions regarding vaccination policies should be balanced between the public health needs and WTP levels. [ABSTRACT FROM AUTHOR]

Background: The introduction of varicella vaccination has significantly reduced the burden of chickenpox in many countries, but outbreaks still occur in populations with high vaccination coverage. To address this, some countries, including the United States, Germany, and Japan, have adopted a two-dose varicella vaccination recommendation. Economic evaluations are crucial for assessing vaccine recommendations; however, there are limited studies exist in Asian countries. Thus, our study aimed to evaluate the cost-benefit of one-dose and two-dose varicella vaccination programs compared to no vaccination in South Korea, incorporating updated data on disease burden and costs. Methods: We utilized data from South Korea’s health databases to estimate varicella burden and vaccination records. Decision tree analysis was employed to compare costs and benefits of vaccination strategies over a ten-year period for the 2012 birth cohort. Sensitivity analyses were conducted to assess the impact of various variables. Results: Both one-dose and two-dose vaccination programs showed cost-benefit compared to no vaccination, with substantial societal cost savings. The one-dose program yielded a benefit-cost ratio (BCR) of1.43, while the two-dose program had a direct BCR of1.28. Sensitivity analyses confirmed the robustness of these findings. Conclusion: Our study demonstrates the economic benefits of varicella vaccination in South Korea, aligning with findings from other countries. While the second dose did not show additional cost savings compared to the one-dose program, other factors like disease severity and transmission dynamics should be considered. Implementing either a one-dose or two-dose varicella vaccination regimen in South Korea could lead to cost reductions and improved cost-effectiveness compared to no vaccination, emphasizing the importance of vaccination programs in reducing disease burden and enhancing public health outcomes.

Introduction Studies on quadrivalent measles, mumps, rubella, and varicella (MMRV) vaccines have indicated a twofold increased relative risk of febrile convulsion (FC) after the first dose compared to MMR and V administered at the same medical visit (MMR+V). Areas covered This narrative review contextualizes FC occurrence after the first MMRV vaccine dose from a clinical perspective and outlines approaches to attenuate FC occurrence post-vaccination. Expert opinion While the relative FC risk increases after the first dose of MMRV compared to MMR+V vaccine in measles-naïve infants, the attributable risk is low versus the overall FC risk in the pediatric population triggered by other causes, like natural exposure to pathogens or routine vaccination. No increased risk of FC has been reported after MMRV co-administration with other routine vaccines compared to MMRV alone. Based on our findings and considering the MMRV vaccination benefits (fewer injections, higher coverage, better vaccination compliance), the overall benefit-risk profile of MMRV vaccine is considered to remain positive. Potential occurrence of FC in predisposed children (e.g. with personal/family history of FC) may be attenuated if they receive MMR+V instead of MMRV as the first dose. It is also important to monitor vaccinees for fever during the first 2 weeks post-vaccination.

Background: Despite the availability of a highly efficacious vaccine, varicella outbreaks are still being reported globally. In this study, we evaluated the real-world effectiveness of varicella vaccination among children between the ages of 1 and 18 years old during the period 2017 to 2019 in Qatar. Methods: A matched case–control study was conducted that included all reported varicella-infected children who visited the primary healthcare system in Qatar from January 2017 to December 2019. The cases were children under the age of 18 years who were clinically diagnosed with varicella. The controls were of the same age, who visited the Primary Health Care Corporation (PHCC) during 2017–2019 with a skin rash where varicella infection was ruled out. The data on varicella vaccination for each participant were obtained from the electronic database in the PHCC during the study period. Results: We included 862 cases of varicella and 5454 matched controls, with a median age of 8 years (IQR 3–12); 47.4% were female and almost 50% were of Qatari nationality. The year 2019 had the highest varicella infection count with a total of 416 cases. The cases were less likely to be vaccinated against varicella, with approximately a quarter (25.6%) of cases and 36.7% of the controls having either one or two doses of the vaccine (p < 0.001). Compared to not being vaccinated, a single dose vaccination showed a 56% reduction in the odds of varicella infection [OR 0.44, 95% CI: 0.34–0.55; p < 0.000], and a two-dose vaccination showed an 86% reduction in the odds of varicella infection [OR 0.13, 95% CI: 0.06–0.29; p < 0.000]. Conclusion: In this multicultural setting, a two-dose varicella vaccination shows reasonable protection against varicella infection. [ABSTRACT FROM AUTHOR]

Since the introduction of Universal Varicella Vaccination (UVV) in the Argentinean National Immunization Program in 2015, a significant decline in the incidence of varicella has been reported. This study aimed to estimate the economic impact of single-dose UVV in Argentina from 2015 to 2019. The economic impact was assessed based on the observed incidence of varicella in the post-UVV period and the number of cases avoided, obtained from a previously published study that used an Autoregressive Integrated Moving Average (ARIMA) model. The weighted average cost per case was calculated using local studies. The post-UVV cost reductions were calculated by multiplying the number of cases avoided from 2015 –2019 by the weighted average cost per case. Data were summarized yearly and by peak (September−November) periods for the target (1−4 years) and overall populations. We estimated avoided costs of United States dollars (USD) $65 million in the target population and $112 million in the overall population over 4 years following UVV introduction. We observed a trend toward greater reductions in costs over time, with substantial differences observed in peak periods. We estimated that the single-dose UVV program considerably reduced the economic burden of varicella in Argentina by avoiding direct and indirect costs associated with varicella management.

Studies on quadrivalent measles, mumps, rubella, and varicella (MMRV) vaccines have indicated a twofold increased relative risk of febrile convulsion (FC) after the first dose compared to MMR and V administered at the same medical visit (MMR+V). This narrative review contextualizes FC occurrence after the first MMRV vaccine dose from a clinical perspective and outlines approaches to attenuate FC occurrence post-vaccination. While the relative FC risk increases after the first dose of MMRV compared to MMR+V vaccine in measles-naïve infants, the attributable risk is low versus the overall FC risk in the pediatric population triggered by other causes, like natural exposure to pathogens or routine vaccination. No increased risk of FC has been reported after MMRV co-administration with other routine vaccines compared to MMRV alone. Based on our findings and considering the MMRV vaccination benefits (fewer injections, higher coverage, better vaccination compliance), the overall benefit-risk profile of MMRV vaccine is considered to remain positive. Potential occurrence of FC in predisposed children (e.g. with personal/family history of FC) may be attenuated if they receive MMR+V instead of MMRV as the first dose. It is also important to monitor vaccinees for fever during the first 2 weeks post-vaccination. Children under 5 years of age can sometimes have convulsions when they get a fever during illness or after vaccination. These are called febrile convulsions, and, in most cases, they leave no lasting damage, and the child outgrows them. After a combined vaccine against four childhood illnesses (measles, mumps, rubella, and varicella) became available, concerns appeared that measles-naïve children who received a first dose of this vaccine had a higher risk of febrile convulsions than children vaccinated with two separate vaccines (one against measles, mumps, and rubella, and one against varicella) administered during the same medical visit. However, this risk is low: during the first or the second week after the first vaccine dose, 1 additional child out of approximately 2500 children who receive the combined vaccine will have a febrile convulsion compared to those receiving 2 separate vaccines. In comparison, febrile convulsions due to any cause will appear in 1 out of 25 children younger than 5 years, and in 1 out of 43 children with measles. The combined vaccine has certain advantages over separate vaccines: children receive fewer injections and are more likely to be fully vaccinated against all four diseases. Children who had febrile convulsions before, or with a close relative who had febrile convulsions could be at higher risk of febrile convulsions after the first dose of the combined vaccine. Provided the informed consent from their parents or legal guardians, these children must receive separate vaccines, while all other children may receive the combined vaccine. [ABSTRACT FROM AUTHOR]

Background: Despite the availability of a highly efficacious vaccine, varicella outbreaks are still being reported globally. In this study, we evaluated the real-world effectiveness of varicella vaccination among children between the ages of 1 and 18 years old during the period 2017 to 2019 in Qatar. Methods: A matched case–control study was conducted that included all reported varicella-infected children who visited the primary healthcare system in Qatar from January 2017 to December 2019. The cases were children under the age of 18 years who were clinically diagnosed with varicella. The controls were of the same age, who visited the Primary Health Care Corporation (PHCC) during 2017–2019 with a skin rash where varicella infection was ruled out. The data on varicella vaccination for each participant were obtained from the electronic database in the PHCC during the study period. Results: We included 862 cases of varicella and 5454 matched controls, with a median age of 8 years (IQR 3–12); 47.4% were female and almost 50% were of Qatari nationality. The year 2019 had the highest varicella infection count with a total of 416 cases. The cases were less likely to be vaccinated against varicella, with approximately a quarter (25.6%) of cases and 36.7% of the controls having either one or two doses of the vaccine (p < 0.001). Compared to not being vaccinated, a single dose vaccination showed a 56% reduction in the odds of varicella infection [OR 0.44, 95% CI: 0.34–0.55; p < 0.000], and a two-dose vaccination showed an 86% reduction in the odds of varicella infection [OR 0.13, 95% CI: 0.06–0.29; p < 0.000]. Conclusion: In this multicultural setting, a two-dose varicella vaccination shows reasonable protection against varicella infection.

Tracking vaccination coverage is a critical component of monitoring a vaccine program. Three different surveillance systems were used to examine trends in varicella vaccination coverage during the United States vaccination program: National Immunization Survey-Child, National Immunization Survey-Teen, and immunization information systems (IISs). The relationship of these trends to school requirements and disease decline was also examined. Among children aged 19-35 months, ≥1 dose of varicella vaccine increased from 16.0% in 1996 to 89.2% by the end of the 1-dose program in 2006, stabilizing around at least 90.0% thereafter. The uptake of the second dose was rapid after the 2007 recommendation. Two-dose coverage among children aged 7 years at 6 high-performing IIS sites increased from 2.6%-5.5% in 2006 to 86.0%-100.0% in 2020. Among adolescents aged 13-17 years, ≥2-dose coverage increased from 4.1% in 2006 to 91.9% in 2020. The proportion of adolescents with history of varicella disease declined from 69.9% in 2006 to 8.4% in 2020. In 2006, 92% of states and the District of Columbia (DC) had 1-dose daycare or school entry requirements; 88% of states and DC had 2-dose school entry requirements in the 2020-2021 school year. The successes in attaining and maintaining high vaccine coverage were paramount in the dramatic reduction of the varicella burden in the United States over the 25 years of the vaccination program, but opportunities remain to further increase coverage and decrease varicella morbidity and mortality. [ABSTRACT FROM AUTHOR]

This study evaluated different varicella vaccination strategies in Jiangsu province, China. A decision-tree Markov model was used to evaluate the cost effectiveness of various varicella vaccination strategies for children, including direct and selective vaccination (serotesting pre-vaccination). A cohort of one-year-old children was followed through 60 one-year Markov cycles. The parameter estimation was based on field work, the literature, and statistical yearbooks. We calculated the incremental cost-utility ratio (ICUR) using the saved quality-adjusted life year (QALY). One-way and probability sensitivity analyses were performed to assess uncertainty. Among 100,000 cohort members, one-dose and two-dose direct vaccination averted 8061 and 10,701 varicella cases, respectively, compared with no vaccination. Furthermore, compared with no vaccination, one-dose and two-dose direct vaccination saved one QALY at the ICUR of USD 21,401.33 and USD 35,420.81, respectively, at less than three times the per capita gross domestic product (USD 47,626.86) of Jiangsu. The ICURs of the one-dose and two-dose selective strategies versus no vaccination were USD 42,623.62 and USD 51,406.35 per QALY gained, respectively. The cost effectiveness results were most sensitive to the QALY loss of outpatients and vaccine prices. Thus, in Jiangsu, one-dose and two-dose direct varicella vaccination in children could be cost effective at the willingness to pay threshold of three times provincial GDP per capita from a societal perspective. The findings were sensitive to the vaccine price and health utility of varicella cases.

Currently available health economic models for varicella infection are designed to inform the cost-effectiveness of universal varicella vaccination (UVV) compared with no vaccination. However, in countries with an existing UVV program, these models cannot be used to evaluate whether to continue with the current varicella vaccine or to switch to an alternative vaccine. We developed a dynamic transmission model that incorporates the historical vaccination program to project the health and economic impact of changing vaccination strategies. We applied the model to Israel, which initiated UVV in 2008 with a quadrivalent vaccine, MMRV-GSK, and switched to MMRV-MSD in 2016. The model was calibrated to pre-vaccination incidence data before projecting the impact of the historical and future alternative vaccination strategies on the clinical burden of varicella. Total costs and QALYs lost due to varicella infections were projected to compare continuing with MMRV-MSD versus switching to MMRV-GSK in 2022. Over a 50-year time horizon, continuing with MMRV-MSD reduced varicella incidence further by 64%, reaching 35 cases per 100,000 population by 2072, versus a 136% increase in incidence with MMRV-GSK. Continuing with MMRV-MSD reduced cumulative hospitalization and outpatient cases by 48% and 58% (vs. increase of 137% and 91% with MMRV-GSK), respectively. Continuing with MMRV-MSD resulted in 139 fewer QALYs lost with total cost savings of 3% compared with switching to MMRV-GSK, from the societal perspective. In Israel, maintaining the UVV strategy with MMRV-MSD versus switching to MMRV-GSK is projected to further reduce the burden of varicella and cost less from the societal perspective.

• One-dose UVV introduction in 2015 significantly reduced clinical burden of varicella in Colombia. • This study showed a direct benefit of UVV in children aged 1–4 years of age (target population). • We also observed indirect benefits of herd immunity in the overall population. • Long-term follow up is needed to understand the full impact on varicella-related mortality. In 2015, one-dose universal varicella vaccination (UVV) was introduced in the Colombian National Immunization Program targeting children aged 12 months, expanding to a two-dose program in 2019. This study aimed to examine the effect of one-dose UVV on the burden of varicella in Colombia. A retrospective study was conducted using national databases to estimate incidence and mortality for the target (1–4 years old), non-target (less than 1 and 5 years and older) and overall (all age groups) populations from the pre-UVV period (January 2008–June 2015) to the post-UVV period (July 2015-December 2019). A time-series analyses with ARIMA modeling was used to project expected varicella incidence and mortality in the absence of UVV in the post-UVV period. UVV impact was estimated by comparing predicted and observed values, providing point estimates and prediction intervals (PI). Overall vaccination coverage rate was over 90 % from 2016-2019. Following UVV introduction, mean annual incidence rates reduced from 743.6 to 676.8 per 100,000 in the target population and from 203.2 to 198.1 per 100,000 in the overall population. Our study estimated a reduction in varicella incidence from 2017, with the highest reduction of 70.5 % (95 % PI: 78.2-54.2) and 54.8 % (95 % PI: 65.0-36.4) observed in 2019 for the target and the overall populations, respectively. The ARIMA model estimated UVV in Colombia to have prevented 198,236 varicella cases from 2015 to 2019. Mortality reduced in the overall population from 0.8 per 1,000,000 to 0.5 per 1,000,000 and from 1.3 per 1,000,000 to 0.5 per 1,000,000 in the target population, in the pre-UVV and post-UVV periods, respectively. However, these differences were not statistically significant. Our study showed a significant reduction in varicella incidence after implementation of a one-dose UVV program in Colombia, increasing over time. Further assessment is needed to evaluate the impact of a two-dose UVV program in Colombia. [ABSTRACT FROM AUTHOR]

One-dose universal varicella vaccination (UVV) was introduced in the Argentinian National Immunization Program in July 2015. This study examined the impact of one-dose UVV on varicella incidence and mortality in Argentina. Incidence and mortality data were obtained from official databases for pre-UVV (January 2008–June 2015) and post-UVV (July 2015–December 2019) periods. Time series analyses with autoregressive integrated moving average (ARIMA) modeling predicted varicella incidence and mortality in absence of UVV in the target (aged 1–4 years) and overall population. Predicted and observed values post-UVV were compared to estimate UVV impact. Mean annual incidence rates per 100,000 reduced from 1999 (pre-UVV) to 1122 (post-UVV) in the target population and from 178 to 154 in the overall population. Significant declines in incidence were observed, reaching reductions of 83.9% (95% prediction interval [PI]: 58.9, 90.0) and 69.1% (95% PI: 23.6, 80.7) in the target and overall populations, respectively, during peak months (September-November) post-UVV. Decreasing trends in mortality rate from 0.4 to 0.2 per 1,000,000 population were observed. Over the last four years, one-dose UVV has significantly reduced varicella burden of disease in Argentina. Continuous efforts to improve vaccination coverage rates and long-term follow-up are needed to better understand the benefits of the UVV program. [ABSTRACT FROM AUTHOR]

Introduction: Postinfectious acute cerebellar syndromes show a wide spectrum of acute severity and can occur with acute febrile illness or vaccine receipt. Varicella has historically been the most common cause, associated with up to 25% of cases in large cohorts. This study aimed to describe the spectrum of syndromes in a setting with high varicella vaccine coverage. Method: Data were collected on children initially identified as "suspected encephalitis" subsequently designated "not-encephalitis" at participating children's hospitals in the Paediatric Active Enhanced Disease Surveillance (PAEDS) network, Australia, as part of the Acute Childhood Encephalitis study. A comprehensive descriptive analysis was undertaken on prospectively identified, national series of children with postinfectious acute cerebellar syndromes from 2013 to 2018. Cases were classified using a previously validated severity score, and the outcome was assessed at 12 months using the Liverpool Outcome Scale score. Results: A total of 20 cases (65% were vaccinated for varicella) were included, of which 70% were subcategorized as acute cerebellar ataxia (ACA), 20% acute cerebellitis (AC), and 10% acute fulminant cerebellitis (AFC). An acute febrile illness was noted in 55% and none were related to varicella or were temporally related to varicella vaccination or other childhood vaccines. A subset (total of 7 children) followed up at 12 months all showed reduced Liverpool Outcome Scale scores. Discussion: The study provides an overall description of this uncommon spectrum of neurologic syndromes and shows the infrequency of varicella zoster virus as a cause in a vaccinated population. [ABSTRACT FROM AUTHOR]

Varicella is a common vaccine-preventable disease that usually presents in children as a mild infection; however, severe complications also occur. The burden of varicella is significant in the terms of incidence, complication, and hospitalization rate related to varicella and economic disease burden. Despite the evidence of overall positive effects of varicella vaccination, there are great differences in the implementation of varicella vaccination and in the uptake of the vaccine from country to country. Improving acceptance of varicella vaccination on the national and on the individual level would decrease the burden of the disease on the health of children and on health-care resources. In studies determining factors of parental acceptance of varicella vaccination questions specific for varicella vaccination were highlighted. Addressing these issues with open, evidence based communication is important to improve and maintain the trust of the public in varicella vaccination.

Varicella is a potentially serious infectious disease caused by Varicella-Zoster Virus (VZV). In Italy childhood varicella vaccine have gradually introduced into national immunization program since 2003 and from 2017 a two-doses schedule has been stated nationally for all newborns and has become compulsory for school attendance. VZV exposures among healthcare workers (HCWs) and patients can be really dangerous and expensive. According to Centers of Disease Control and Italian national immunization plan health care, institutions should verify that all HCWs have clear evidence of immunity to VZV and should ensure that susceptible subjects will receive 2 doses of VZV vaccine. Currently, the vaccination of HCWs is not compulsory in Italy and the risk of varicella infection among these subjects is not well known. We evaluated the clinical records of 840 HCWs (256 male and 584 female) who underwent the annual occupational screening, from 1st January to 31st August 2018. HCWs were divided into three subgroups according to their age: 18–30, 31–40, and over 40 years old. We compared the mean values of IgG-specific antibodies between the age group through analysis of variance (ANOVA). A total of 784 (93.33%) HCWs were protected for VZV IgG antibodies level. There wasn’t a significant difference between male and female while was found between age group (P

Background: The introduction of varicella vaccination has significantly reduced the burden of chickenpox in many countries, but outbreaks still occur in populations with high vaccination coverage. To address this, some countries, including the United States, Germany, and Japan, have adopted a two-dose varicella vaccination recommendation. Economic evaluations are crucial for assessing vaccine recommendations; however, there are limited studies exist in Asian countries. Thus, our study aimed to evaluate the cost-benefit of one-dose and two-dose varicella vaccination programs compared to no vaccination in South Korea, incorporating updated data on disease burden and costs., Methods: We utilized data from South Korea's health databases to estimate varicella burden and vaccination records. Decision tree analysis was employed to compare costs and benefits of vaccination strategies over a ten-year period for the 2012 birth cohort. Sensitivity analyses were conducted to assess the impact of various variables., Results: Both one-dose and two-dose vaccination programs showed cost-benefit compared to no vaccination, with substantial societal cost savings. The one-dose program yielded a benefit-cost ratio (BCR) of1.43, while the two-dose program had a direct BCR of1.28. Sensitivity analyses confirmed the robustness of these findings., Conclusion: Our study demonstrates the economic benefits of varicella vaccination in South Korea, aligning with findings from other countries. While the second dose did not show additional cost savings compared to the one-dose program, other factors like disease severity and transmission dynamics should be considered. Implementing either a one-dose or two-dose varicella vaccination regimen in South Korea could lead to cost reductions and improved cost-effectiveness compared to no vaccination, emphasizing the importance of vaccination programs in reducing disease burden and enhancing public health outcomes., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Young June Choe reports financial support was provided by SK Bioscience Co Ltd. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Author(s).)

One-dose universal varicella vaccination (UVV) was introduced in the Argentinian National Immunization Program in July 2015. This study examined the impact of one-dose UVV on varicella incidence and mortality in Argentina. Incidence and mortality data were obtained from official databases for pre-UVV (January 2008–June 2015) and post-UVV (July 2015–December 2019) periods. Time series analyses with autoregressive integrated moving average (ARIMA) modeling predicted varicella incidence and mortality in absence of UVV in the target (aged 1–4 years) and overall population. Predicted and observed values post-UVV were compared to estimate UVV impact. Mean annual incidence rates per 100,000 reduced from 1999 (pre-UVV) to 1122 (post-UVV) in the target population and from 178 to 154 in the overall population. Significant declines in incidence were observed, reaching reductions of 83.9% (95% prediction interval [PI]: 58.9, 90.0) and 69.1% (95% PI: 23.6, 80.7) in the target and overall populations, respectively, during peak months (September-November) post-UVV. Decreasing trends in mortality rate from 0.4 to 0.2 per 1,000,000 population were observed. Over the last four years, one-dose UVV has significantly reduced varicella burden of disease in Argentina. Continuous efforts to improve vaccination coverage rates and long-term follow-up are needed to better understand the benefits of the UVV program.

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. 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. 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. 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. [ABSTRACT FROM AUTHOR]

Herpes zoster (HZ) is caused by reactivation of the varicella-zoster-virus (VZV). Childhood varicella vaccination, as recommended in Germany in 2004, may reduce the risk of HZ in vaccinated children but also virus circulation and thus the booster possibility of latent infected persons. In this context we analyzed age-specific trends in HZ epidemiology in Germany using data on HZ-associated outpatient consultations in participating sentinel sites and HZ-associated cases in all hospitals since 2005. We analyzed two separate time periods that differed in sentinel management and data integrity. For the period 2005–2010, we found a decrease in HZ-associated outpatient consultations in 1- to 4-year-olds (IRR = 0.72, 95%CI 0.63-0.81, p

Background: Despite high 1-dose vaccination coverage, breakthrough varicella infections still occur. Therefore, 2-dose vaccination is recommended to enhance the immune response to the virus. However, the reported incremental vaccine effectiveness (VE) of 2-dose vaccination varies widely among studies. Methods: To determine the overall effectiveness, immunogenicity and safety of one vs. two-dose varicella vaccination, we searched five databases for articles published during 1995–2017. Results: The incremental VE/efficacy of 2-dose vaccination was 79% (95% confidence interval [CI]: 56%−90%) in randomized controlled trials，63% (95% CI: 36%−79%) in cohort studies and 81% (95% CI: 65%−90%) in case-control studies. Regarding immunogenicity, the pooled standardized mean differences (SMD) of geometric mean titer (GMT) and the pooled relative risk (RR) of seroconversion for 2-dose vs. 1-dose vaccine were 562.44 (95% CI: 471.78–653.10) and 1.03 (95% CI: 1.02–1.04), respectively. Children who received second dose vaccination were at increased risk of grade 3 redness (RR: 4.93, 95% CI: 1.89 − 12.87) and swelling of any intensity (RR: 1.34, 95% CI: 1.08 − 1.66). Conclusions: Two-dose varicella vaccination resulted in higher levels of immunogenicity and provided superior protection than 1-dose vaccination. Safety profiles showed 2-dose vaccination was well tolerated but the incidence of grade 3 redness and of any intensity was significantly higher.

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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: children <1 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 and <4.0/100,000 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 infants <1 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 class <1 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. [ABSTRACT FROM AUTHOR]

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 with <3 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. [ABSTRACT FROM AUTHOR]

Antibody response against varicella-zoster virus (VZV) is frequently assessed by whole-virus- (anti-VZV) or glycoprotein-based ELISAs. This study compared antibody concentrations measured by an assay quantifying anti-VZV glycoprotein E (anti-gE) and anti-VZV ELISA in 12–23-month-olds, receiving two varicella vaccine doses in a phase III trial (NCT02570126). Samples (pre- and 42 days post-each vaccination) initially tested with anti-VZV ELISA were re-tested with anti-gE ELISA. Of 1138 samples from 397 children, 757 were positive by anti-VZV (antibody concentration ≥25 mIU/mL) and 758 by anti-gE ELISA (≥97 mIU/mL). There were 375 double-negative and only 11 discrepant samples. The overall agreement was 99.03% (95% confidence interval: 98.28–99.52; McNemar p-value = 1). The ratio between antibody geometric mean concentrations (anti-gE/anti-VZV) for the 752 double-positive samples was 3.78 overall, 4.75 post-first, and 3.01 post-second vaccination. The anti-gE ELISA is a valid alternative for trials assessing antibody response to new varicella vaccines versus established ones, used as control. [ABSTRACT FROM AUTHOR]

Background: Solid organ transplant (SOT) recipients are a special group of patients who require comprehensive evaluation for preventable infectious diseases before transplantation. The main aim of our study was to investigate the number of heart, lung, and liver (HLL) transplant recipients who were evaluated for their immune status against measles, mumps, rubella (MMR), and varicella (VZV). As a secondary aim, we investigated whether pre‐transplant infectious disease consultation (IDC) improves vaccination rates. Methods: This study was an institution‐based retrospective analysis of HLL transplant recipients born in or after 1957 and evaluated at Mayo Clinic, FL Transplant Center between January 1st, 2016 and December 31st, 2017. Data collection was obtained from electronic medical records. The vaccination rates were compared by univariate analysis based on IDC and no ID consultation (NIDC). Results: One hundred and eighty‐seven (77%) of a total 242 patients received an IDC pre‐transplantation. Varicella IgG levels were screened in all 187 IDC candidates. Among the 187 IDC patients, mumps, measles, and rubella IgG serologies were performed in 9 (5%), 21 (11%), and 51 (27%), respectively. Among all 242 patients, vaccines given included 2 (0.8%) MMR, 10 (4.1%) varicella and 85 (35.12%) Zostavax. Univariate analysis revealed that Zostavax was given to 76 (40.6%) pre‐transplant IDC patients and only in 9 (16.7%) NIDC patients (P <.001). Conclusions: Despite the relatively high IDC rate, patients' screened numbers for MMR IgG levels were low. Results pointed out the need for MMR protocol‐driven serologic screening as well as for VZV and IDC prior to transplantation to increase vaccination rates. [ABSTRACT FROM AUTHOR]

Abstract Background In 2004, universal childhood varicella vaccination was introduced in Germany. We aimed to determine the age-specific prevalence of anti-varicella zoster virus (VZV) IgG-antibodies among children in the pre-varicella vaccine era in Germany, to identify factors associated with VZV seropositivity, and to assess the suitability of a commercially available ELISA for VZV seroepidemiological studies by comparing it with an in-house fluorescent antibody to membrane antigen test (FAMA) as the gold standard. Methods Serum samples of 13,433 children and adolescents aged 1–17 years included in the population-based German Health Interview and Examination Survey for Children and Adolescents (KiGGS; conducted 2003–2006) were tested for anti-VZV IgG by ELISA. All samples with equivocal ELISA results and a random selection of ELISA-negative and -positive samples were tested by FAMA. Statistical analyses were conducted using a weighting factor adjusting the study population to the total population in Germany. Seroprevalences were calculated as percentages (%) with a 95% confidence interval (CI). Odds ratios (OR) were computed by multivariate logistic regression to determine the association between socio-demographic factors and VZV seropositivity. Results The VZV seropositivity rate was 80.3% (95% CI: 79.3–81.3) in varicella-unvaccinated children and adolescents. VZV seropositivity rates differed significantly between age groups up to age 6 years, but not by gender. Of 118 retested serum samples with an equivocal ELISA result, 45.8% were FAMA-positive. The proportion of samples tested as false-negative in by ELISA varied by age group: 2.6% in children aged 1–6 and 9% in children aged 7–17 years. Multivariate analyses showed that age, having older siblings, and early daycare start were associated with seropositivity in preschoolers; migration background reduced the chance of VZV seropositivity in schoolchildren (OR: 0.65; 0.43–0.99) and adolescents (OR: 0.62; 0.4–0.97). Conclusion In the pre-varicella vaccine era, most children in Germany contracted varicella by age six. Schoolchildren with a migration background and children without siblings have an increased risk of being VZV seronegative and should be targeted for catch-up vaccination, if they have no history of chickenpox. ELISAs are suitable for use in population-level serosurveys on VZV, but samples with equivocal ELISA results should be retested by FAMA.

Background 2-dose varicella vaccination has been available in Ningbo city, China since 2014 in the private sector. This study aimed to evaluate the breakthrough varicella infection rate, and to examine overall and incremental effectiveness of 2-dose varicella vaccination among Chinese children. Methods A retrospective investigation was done among native children born from 2008 to 2013 in active surveillance area in Ningbo, China. Between 2009 and 2016, demographic information and data on varicella vaccination were collected by Ningbo’s Immunization Information System, and information of varicella infections were obtained from China Information System for Disease Control and Prevention. The logistic regression was conducted to estimate varicella vaccine effectiveness (VE). Result A total of 107,324 local children were enrolled in the cohort analysis and 95.11% of these children with no varicella disease history received at least 1-dose varicella vaccine from 2009 to 2016. The total breakthrough varicella infection rate (BVR) was 0.37% for all the vaccinated children and 0.04% for 2-dose vaccination. The annual BVR ranged from 0.01% to 0.49% for 1-dose of varicella vaccine and from 0.01% to 0.02% for 2-dose. The infection rates both in the unvaccinated children and the 1-dose children were decreasing after 2-dose vaccination implemented in 2014 (Unvaccinated: P  < 0.001 for trend; 1-dose: P  = 0.003 for trend). The VE against all varicella was 50.3% (95% CI: 39.8%–59.0%) for 1-dose ( P  < 0.001) and 98.7% (95% CI: 98.1%–99.1%) for 2-dose ( P  < 0.001), and the incremental VE was 97.4% (95% CI: 96.2%–98.2%) compared with 1-dose ( P  < 0.001). Conclusion The 2-dose regimen provided excellent protection to prevent all varicella, and the universal 2-dose regimen of varicella vaccine should be recommended to prevent the varicella disease among children in China. [ABSTRACT FROM AUTHOR]

Background: Despite high 1-dose vaccination coverage, breakthrough varicella infections still occur. Therefore, 2-dose vaccination is recommended to enhance the immune response to the virus. However, the reported incremental vaccine effectiveness (VE) of 2-dose vaccination varies widely among studies. Methods: To determine the overall effectiveness, immunogenicity and safety of one vs. two-dose varicella vaccination, we searched five databases for articles published during 1995-2017. Results: The incremental VE/efficacy of 2-dose vaccination was 79% (95% confidence interval [CI]: 56%−90%) in randomized controlled trials，63% (95% CI: 36%−79%) in cohort studies and 81% (95% CI: 65%−90%) in case-control studies. Regarding immunogenicity, the pooled standardized mean differences (SMD) of geometric mean titer (GMT) and the pooled relative risk (RR) of seroconversion for 2-dose vs. 1-dose vaccine were 562.44 (95% CI: 471.78-653.10) and 1.03 (95% CI: 1.02-1.04), respectively. Children who received second dose vaccination were at increased risk of grade 3 redness (RR: 4.93, 95% CI: 1.89 − 12.87) and swelling of any intensity (RR: 1.34, 95% CI: 1.08 − 1.66). Conclusions: Two-dose varicella vaccination resulted in higher levels of immunogenicity and provided superior protection than 1-dose vaccination. Safety profiles showed 2-dose vaccination was well tolerated but the incidence of grade 3 redness and of any intensity was significantly higher. [ABSTRACT FROM AUTHOR]

Background Varicella vaccine was introduced into the Brazilian Immunization Program in October 2013, as a single-dose schedule administered at 15 months of age. Its effectiveness had not yet been assessed in the country. Methods A matched case-control study was carried out in São Paulo and Goiânia (Southeast and Midwest regions, respectively), Brazil. Suspected cases, were identified through a prospective surveillance established in the study sites. All cases had specimens from skin lesion collected for molecular laboratory testing. Cases were confirmed by either clinical or PCR of skin lesions and classified as mild, moderate, and severe disease. Two neighborhood controls were selected for each case. Cases and controls were aged 15–32 months and interviewed at home. Evidence of prior vaccination was obtained from vaccination cards. Univariate and multivariate logistic regression models were used, and odds ratio and its respective 95% confidence intervals were estimated. Vaccine effectiveness was estimated by comparing de odds of having received varicella vaccine among cases and controls. Results A total of 168 cases and 301 controls were enrolled. Moderate and severe illness, was found in 33.3% and 9.9% of the cases. Effectiveness of a single dose varicella vaccine was 86% (95%CI 72–92%) against disease of any severity and 93% (95%CI 82–97%) against moderate and severe disease. Out of 168 cases, 81.8% had positive PCR results for wild-type strains, and 22.0% were breakthrough varicella cases. Breakthrough cases were milder compared to non-breakthrough cases (p < .001). Conclusions Effectiveness of single dose varicella vaccine in Brazil is comparable to that in other countries where breakthrough varicella cases have also been found to occur. The goal of the varicella vaccination program, along with disease burden and affordability should be taken into consideration when considering the adoption of a second dose of varicella vaccine into national immunization programs. [ABSTRACT FROM AUTHOR]

Background: Varicella zoster virus is the etiologic agent of primary varicella (chickenpox) during childhood, and varicella vaccination has not been introduced in Iran. The aim of this study is to estimate cost-effectiveness of one- and two-dose Varicella Vaccination Program in Iran. Methods: A decision-tree model was conducted to evaluate the cost-effectiveness of the Varicella Vaccination Program in a cohort of 12 months children in Iran. Epidemiologic parameters of varicella were extracted from local and international sources, and cost of disease was estimated based on societal prospective in 2015 US$. Incremental cost per disability-adjusted life years (DALY) averted calculated as final outcome. Sensitivity analysis was also performed for lower and upper estimate of incidence, DALY, and vaccine efficacy. Results: Considering the vaccine efficacy of 95%, for the two-dose and 85% for the one-dose vaccination, incremental cost-effectiveness ratio (ICER) per DALYs averted were US$41,531 and US$17,280, respectively. ICER has changed between (US$ 6,177-US$167,047) in lower and upper base estimate of epidemiological burden parameters in sensitivity analysis. Conclusions: Varicella vaccination is not cost-effective in Iran in one-dose and two-dose scenario under the assumptions of this study in base case scenario according to the threshold of incremental cost per DALY averted less than three time of GDP per capita in Iran = US$ 14,292. One-dose vaccination program might be cost-effective in upper scenario of epidemiological burden of varicella in sensitivity analysis. [ABSTRACT FROM AUTHOR]