Varicella Incidence Research Articles

Varicella complications in children one-site Polish population – a 19- year long survey

The aim of this study was to describe the epidemiology of chickenpox complications in children, based on a 19-year long survey. This publication constitutes a review of medical records of 761 patients under the age of 18 who were hospitalized at the T. Browicz Provincial Hospital for Infectious Diseases in Bydgoszcz, Poland from the 1st of January 1999 to the 31st of December 2017. Over the study period, 761 children diagnosed with varicella complications were hospitalized. The mean number of hospitalizations in each year amounted to 40. The median age of admitted patients was 4 years. The median length of hospitalization was 5 days (ranged from 1 to 30 days). The most frequent varicella complications included respiratory tract infections – 229/761 (30.1%), bacterial skin infections – 189/761 (24.8%) and gastrointestinal tract disorders – 142/761 (18.6%). Pneumonia, bronchitis and gastrointestinal tract disturbances, were reported most often in children under 2 years of age, while neurological complications occurred most frequently in children at 3-6 years of age. No significant differences in the number of varicella complications between immunocompromised and immunocompetent children were reported. Varicella complications mainly affect the youngest immunocompetent children. Population-wide vaccination and herd immunity appears to be the best way to reduce the incidence of chickenpox and the rate of varicella complications. This study gives support for inclusion of universal varicella vaccine in the National Immunization Program in Poland.

2479. Varicella Zoster Immune Globulin Is Effective up to 10 Days Following Varicella Exposure in Pregnant Women, Immunocompromised Patients, and Infants: Results From a Large, Open-Label Expanded-Access Program

BackgroundThere are more than 300,000 cases of varicella annually; nonimmune individuals exposed to varicella-zoster (VZ) virus have a high likelihood of developing varicella. VZ immune globulin (VARIZIG®) is used for postexposure prophylaxis to prevent or attenuate VZ infection in high-risk individuals. We assessed varicella incidence and severity in high-risk subjects after administration of VZ immune globulin.MethodsThis open-label expanded-access program provided VZ immune globulin to physician-identified, high-risk subjects exposed to varicella. Subjects included immunocompromised children/adults, infants (including preterm infants, newborns whose mothers had VZ infection <5 days before or <2 days after delivery, and infants <1 year of age), and pregnant women. VZ immune globulin (125 IU/10 kg [up to 625 IU]) was administered intramuscularly, ideally ≤96 hours, but up to 10 days, postexposure. Incidence of varicella rash and severity (>100 pox, pneumonia, encephalitis) were assessed up to 42 days after administration.ResultsThe efficacy population (n = 505) included 263 immunocompromised subjects (32 adults, 231 pediatric), 137 pregnant women, and 105 infants. More than 97% of exposures fit the CDC definition. Varicella incidence was low in immunocompromised subjects (4.5%, n = 12/269), pregnant women (7.3%, n = 10/137), and infants (11.4%, n = 12/105) and was similar when comparing administration ≤ 96 hours vs. up to 10 days postexposure (6.2% vs. 9.4%, respectively). Of 34 subjects with varicella, 54% were exposed in the household; 5 were considered severe. Common adverse events were pyrexia (4%), neutropenia (3%), and headache (3%). There were no product-related deaths and only 1 serious adverse event (serum sickness) considered probably related to VZ immune globulin.ConclusionPostexposure administration of VZ immune globulin resulted in low rates of varicella in high-risk subjects, regardless of administration timing within 10 days postexposure. VZ immune globulin—which is FDA-approved, recommended by the CDC, and widely available—was well tolerated and safe in high-risk subjects.Disclosures M. Levin, Merck: Consultant and Scientific Advisor, Consulting fee and Research support. GlaxoSmithKline: Consultant and Scientific Advisor, Consulting fee and Research support. Saol Therapeutics: Consultant and Scientific Advisor, Consulting fee. J. Duchon, Saol Therapeutics: Consultant and Scientific Advisor, Consulting fee. G. K. Swamy, Saol Therapeutics: Consultant and Scientific Advisor, Consulting fee.

2477. Impact of Varicella Vaccination in the United States (US): A Dynamic Model-Based Analysis

BackgroundRoutine childhood immunization with varicella vaccine was first recommended in the United States in 1995 as a 1-dose regimen for children aged 12–18 months, with updated recommendations in 2006 for a 2-dose regimen (first dose at 12–15 months, second dose at 4–6 years). Our objective was to estimate the impact of the US varicella vaccination program.MethodsWe developed a dynamic transmission model to predict the impact on varicella vaccination on health outcomes in the United States. Vaccine coverage rates were extracted from the US National Immunization Survey (NIS); first dose varicella vaccine coverage went from 12% in 1996 to 91% by 2016 for children 18 months old, and second dose coverage starting in 2006 at 5% increasing by 2016 to 94% for children 5 years old; we assumed that 50% of children with no history of vaccination or infection by age 13 would become vaccinated. Interactions between age groups were empirically characterized, and the model was calibrated using age-specific pre-vaccination varicella incidence data.. Vaccine effectiveness was represented via vaccine take and waning immunity estimated from a 10-year trial.ResultsThe model projected reductions of varicella incidence in all ages (and ages <15 years) of 46% (46%) in 2001, 76% (76%) in 2006, 78% (81%) in 2011, and 89% (93%) in 2016 (Figure 1). The projected reductions in varicella cases and varicella-related hospitalizations and deaths for all ages were 74%, 70%, and 66% by 2006 (one-dose era), respectively, increasing to 89%, 70%, and 69% by 2016 (two dose era), respectively (Figure 2). We estimate that between 1996 and 2016, 71,885,382 cases of varicella were prevented in the United States, together with 178,248 varicella-related hospitalizations and 1,496 deaths.ConclusionOur estimates are slightly lower than previously reported US surveillance data which identified a 97.4% (92.9%-97.9%) reduction between 1993–1994 and 2013–2014 in IL, MI, TX, and WV (WER 2016). Likely, this difference is related to under ascertainment of milder cases. This model can be used to estimate the public health benefits of varicella vaccination. The use of a dynamic transmission model does, however, have limitations, including assumptions about age-specific risk and severity of breakthrough disease and the use of a static population. Disclosures L. Wolfson, Merck & Co., Inc.: Employee and Shareholder, Salary. J. Kyle, Merck & Co., Inc.: Independent Contractor, Salary. B. Kuter, Merck: Employee and Shareholder, Salary. M. Levin, Merck Sharp & Dohme Corp.: Scientific Advisor, Consulting fee, Licensing agreement or royalty and Research grant. V. Daniels, Merck & Co., Inc.: Employee and Shareholder, Salary.

Epidemiology of Breakthrough Varicella after the Implementation of a Universal Varicella Vaccination Program in Taiwan, 2004\u20132014

National one-dose varicella vaccination at 12 months of age was implemented in Taiwan since 2004.Our study aimed to evaluate breakthrough varicella (BV) in post-vaccine era and its associated risk factors. We retrospectively identified children vaccinated against varicella between 12–23 months of age during 2004–2008. Their vaccination information was extracted from the national vaccination registry system and linked to the 2004–2014 National Health Insurance database. BV was defined as a diagnosis of varicella (ICD-9-CM codes 052 and 052.0–052.9) beyond 42 days post-vaccination. Multiple Cox regression model was used to identify risk factors for BV. Among 932,874 enrolled vaccinees, 26,446 (2.8%) had BV and 219 (0.024%) required hospitalization over the study period. Varicella incidence declined from 4.71 per 1000 person-year (PY) in 2004 to 0.81/1000 PY in 2014. BV incidence decreased from 3.90/1000 PY at first year to 1.94/1000 PY at 11th year after vaccination. Females had a lower risk for BV than males (hazard ratio [HR] 0.85, 95% CI, 0.83–0.87); Varivax® recipients had a lower risk for BV than Varilrix® recipients (HR 0.75, 95% CI, 0.72–0.78). Our study showed the incidence of varicella, BV and varicella-related hospitalizations in Taiwan were kept low in post-vaccine era.

Incidence of varicella in children in Jeju-do, Korea, 2005-2016: age-period-cohort analysis.

OBJECTIVESAlthough the nationwide inoculation rate of varicella vaccine was approximately 95% in Korean children recently, the number of notified varicella cases is unexpectedly continuously increasing till now. To suggest some hypotheses regarding this discrepancy, an age-period-cohort (APC) analysis as a descriptive epidemiology study was conducted for children residing in Jeju-do, Korea.METHODSThe raw data were obtained from the nationwide database for insurance claim of healthcare fee provided by the National Health Insurance Service, Korea. The selection criteria were children aged 2-13 years who visited any healthcare center due to varicella from 2005 to 2016 while residing in Jeju-do. After calculating the birth cohort-specific crude incidence rates by age and year, the intrinsic estimator method was used to perform the APC analysis.RESULTSAs the annual crude incidence rates decreased with increasing age between 2005 and 2016, the age and period effects also decreased. The intrinsic estimator coefficients suggesting the cohort effect shifted from positive to negative in 2011, the starting year of free varicella vaccine program in Jeju-do.CONCLUSIONSThe results suggested that inoculated varicella vaccines have preventive effects. However, further studies to evaluate waning immunity would be needed.

BINARY METHOD OF THE EPIDEMIOLOGICAL ANALYSIS OF INFECTIOUS INCIDENCE

Article purpose. To present the binary method of the epidemiological analysis of infectious incidence recommended for the characteristic of factors of social-and-ecological systems her defining. Materials and methods. The method of the binary analysis is developed on the basis of the methods of complex studying of epidemic process used in domestic epidemiology which have received the name “retrospective epidemiological analysis of incidence”. For demonstration long-term and annual dynamics of incidence of chicken pox in Vladivostok from 1997 to 2009 is used. The received results. In the binary analysis consecutive division of cumulative incidence into components is carried out, in the beginning, on the leading approaches characterizing biological, social and natural essence of epidemic process and then, by additional criteria, allows to create the statistical model of the studied object suitable for a research of the global phenomena. From biological factors - participation and a role of the infectious and immunological mechanism. Among natural factors - seasonal and year-round elements; social factors - casual and natural manifestations. In Vladivostok from 1997 to 2009 the share of periodic incidence has made 16,7%, basic incidence - 83,3%. Basic incidence was formed due to year-round incidence (17,8%) and seasonal, the main share. In general 82,2% are the share of seasonal incidence and, it forms both the most part of basic incidence, and all periodic incidence. Share of random factors in incidence not of a bike (7,3%). Incidence is formed by mainly natural factors - 92,7%. Conclusion. Use of a binary method has allowed to create logical model of development of epidemic process at chicken pox in Vladivostok. The accounting of a role of the leading factors will be useful to optimization of epidemiological surveillance. The technique of studying of structural elements of the social-and-ecological systems defining formation of incidence of the population is presented in article. Biological factors are the participation and the role of the infectious and immunological mechanism. Natural factors are seasonal and year-round elements; social factors are casual and natural manifestations.

BINARY METHOD OF THE EPIDEMIOLOGICAL ANALYSIS OF INFECTIOUS INCIDENCE

Article purpose. To present the binary method of the epidemiological analysis of infectious incidence recommended for the characteristic of factors of social-and-ecological systems her defining. Materials and methods. The method of the binary analysis is developed on the basis of the methods of complex studying of epidemic process used in domestic epidemiology which have received the name “retrospective epidemiological analysis of incidence”. For demonstration long-term and annual dynamics of incidence of chicken pox in Vladivostok from 1997 to 2009 is used. The received results. In the binary analysis consecutive division of cumulative incidence into components is carried out, in the beginning, on the leading approaches characterizing biological, social and natural essence of epidemic process and then, by additional criteria, allows to create the statistical model of the studied object suitable for a research of the global phenomena. From biological factors - participation and a role of the infectious and immunological mechanism. Among natural factors - seasonal and year-round elements; social factors - casual and natural manifestations. In Vladivostok from 1997 to 2009 the share of periodic incidence has made 16,7%, basic incidence - 83,3%. Basic incidence was formed due to year-round incidence (17,8%) and seasonal, the main share. In general 82,2% are the share of seasonal incidence and, it forms both the most part of basic incidence, and all periodic incidence. Share of random factors in incidence not of a bike (7,3%). Incidence is formed by mainly natural factors - 92,7%. Conclusion. Use of a binary method has allowed to create logical model of development of epidemic process at chicken pox in Vladivostok. The accounting of a role of the leading factors will be useful to optimization of epidemiological surveillance. The technique of studying of structural elements of the social-and-ecological systems defining formation of incidence of the population is presented in article. Biological factors are the participation and the role of the infectious and immunological mechanism. Natural factors are seasonal and year-round elements; social factors are casual and natural manifestations.

Pneumonia varicella in adults.

Varicella is a widespread and well-studied disease. However, there is few information on varicella pneumonia (VP) caused by Varicella Zoster Virus (VZV) and it's contradictory. The literature data on VP is given. The clinical case of VP in a young healthy adult is presented. Initially, an easily flowing varicella on the 5th day of the disease was characterized by a sharp increase of intoxication, the appearance of nausea, vomiting, diarrhea, rapid development of acute respiratory failure. Intensive care was not able to prevent the onset of a fatal outcome within 24 hours from the appearance of the first symptoms of acute respiratory failure. A complex postmortem pathoanatomical study with use of the immunohistochemical method convincingly demonstrated the etiological role of VZV in the development of fatal necrotic viral pneumonia. Attention is drawn to the mandatory use of acyclovir even in cases of suspicion of VP. The introduction of vaccination against V in the National Calendar of preventive vaccinations of the Russian Federation is the only way to reduce the incidence of varicella in the country.

PRM121 - COMPARATIVE IMPACT OF TWO VARICELLA VACCINES ON VARICELLA EPIDEMIC DYNAMICS IN ITALY

Varicella is a common, vaccine-preventable disease associated with significant socio-economic burden. Following the experience from eight pilot regions, Italy has made varicella vaccination mandatory since 2017. This study compares the impact of two monovalent/tetravalent vaccines in a 2-dose schedule as recommended in Italy. A previously published age-structured dynamic model of varicella vaccination was used to compare the two vaccines. Given the differences in the immunogenicity profiles, an efficacy of 67.2% and 78.0% was considered for GSK and MSD first dose monovalent vaccines, respectively. GSK and MSD tetravalent vaccines were assumed to result in 95.4% and 98.3% of full protection with the second dose, respectively. The average vaccination coverage of 84.2% at 24 months in the eight Italian pilot regions was conservatively assumed for both first and second doses. Model outputs include the incidence of wild-type (WT) and breakthrough (BKT) varicella; and varicella inpatient days. Varicella incidence before vaccination introduction was 910 per /100,000 person-year. At the post-immunization equilibrium, annual WT infections were similar between the two vaccines with 18.1% and 17.5% of the pre-vaccination period for GSK and MSD vaccines, respectively. BKT infections represented 72.6% and 72.4% of all infections for GSK and MSD vaccines, respectively. Both vaccines resulted in a similar age distribution at equilibrium; with 72.9% of WT and 54.9% of BKT infections occurring in age groups less than 25 years old with GSK vaccine compared to 70.5% of WT and 52.3% of BKT infections with MSD vaccine. The average age of WT and BKT infections shifted to the 15-24 age group with both vaccines. Varicella inpatient days were reduced by 67.0% and 67.1% with GSK and MSD vaccines, from the pre-vaccination era, respectively. The difference in efficacy between the two varicella vaccines does not translate into differences in varicella epidemic dynamics in Italy.

PIN56 - COST-EFFECTIVENESS OF VARICELLA AND HERPES ZOSTER VACCINATION IN THE SWEDISH POPULATION

Varicella (chickenpox) is caused by primary infection of the varicella zoster virus. It is a highly contagious disease and most people are infected as children. At the age of 12, only 3% are susceptible in Sweden. After primary infection, the virus can be reactivated later in life and cause herpes zoster (shingles). The aim was to assess cost-effectiveness of including varicella vaccine to children and herpes zoster vaccine to elderly in the Swedish vaccination program, by comparing health-effects and costs with a vaccination program versus no vaccination program. We developed a dynamic transmission model to simulate the burden of varicella and herpes zoster in the Swedish population, accounting for indirect effects of vaccination (herd-immunity). The main outcome was number of individuals with varicella and herpes zoster. The model was calibrated to fit Swedish data. Costs included in the analysis were those incurred when treating varicella and herpes zoster, production losses during sick-leave or when caring for a sick child, and acquisition and administration of two vaccines. Health effects were measured as quality-adjusted life years. The time horizon was set to 100 years. Both health effects and costs were discounted by 3% annually, and were accumulated over the time horizon to create an incremental cost-effectiveness ratio. Preliminary results show that vaccination is likely to be cost-effective. The shingles incidence would increase in the short term, whilst the incidence of varicella would decrease – both due to direct effects among vaccinated as well as through herd-immunity. This has an effect on the cost-effectiveness, since the cost of implementing the program occur immediately, whilst some if the benefit occur in the future. The cost-effectiveness of the vaccines are highly dependent on price of the vaccine, and the level of discounting, since many of the benefits of a program occur in the future.

Chickenpox in Poland in 2016

Chickenpox is a common disease in Poland. Annually, between 160,000 and 220,000 cases are registered. On average, there is an increase in incidence every 4 years. Therefore, it is justified to use preventive vaccination that effectively protects against infection. In Poland, since 2002, these are recommended vaccinations. To assess the epidemiological situation of chickenpox in Poland in 2016. and a comparison with the situation in previous years. Assessment of the epidemiological situation of chickenpox in Poland in 2016. was based on the results of the analysis of aggregate data published in the annual bulletins: “Infectious diseases and poisoning in Poland in 2016” and “Protective Vaccination in Poland in 2016. (Czarkowski MP, et al. Warsaw, NIZP-PZH, GIS). In addition, the recommendations from the Protective Vaccine Program for 2016 were used. In 2016, 160,707 cases of chickenpox were registered in Poland, 14.3% fewer cases than in the previous year. The incidence of varicella in 2016 was 418.2 per 100,000. and was lower than in 2015 by 14.3%. The lowest incidence was registered in the Podkarpackie Voivodeship - 259.3 / 100,000, the highest and the highest one in 2015 in the Śląskie Voivodship - 542.9 / 100,000. Children aged 0-4 (77 258) and 5-9 (60,818) became ill most. The incidence of men pox was higher than for women, and the rural population higher than for urban residents. Hospitalization due to chickenpox in 2016 included 1 219 people, which accounted for 0.76% of the total number of registered cases. 66,357 people were vaccinated against varicella. In 2016, there was a decrease in the number of smallpox cases, which may be explained by activities in the field of health education aimed at protective vaccination and indicating the benefits of preventive vaccination, as well as increasing the knowledge of the general public in the prevention of infectious diseases by vaccination.

Modeling the impact of changes in day-care contact patterns on the dynamics of varicella transmission in France between 1991 and 2015.

Annual incidence rates of varicella infection in the general population in France have been rather stable since 1991 when clinical surveillance started. Rates however show a statistically significant increase over time in children aged 0–3 years, and a decline in older individuals. A significant increase in day-care enrolment and structures’ capacity in France was also observed in the last decade. In this work we investigate the potential interplay between an increase of contacts of young children possibly caused by earlier socialization in the community and varicella transmission dynamics. To this aim, we develop an age-structured mathematical model, informed with historical demographic data and contact matrix estimates in the country, accounting for longitudinal linear increase of early childhood contacts. While the reported overall varicella incidence is well reproduced independently of mixing variations, age-specific empirical trends are better captured by accounting for an increase in contacts among pre-school children in the last decades. We found that the varicella data are consistent with a 30% increase in the number of contacts at day-care facilities, which would imply a 50% growth in the contribution of 0-3y old children to overall yearly infections in 1991–2015. Our findings suggest that an earlier exposure to pathogens due to changes in day-care contact patterns, represents a plausible explanation for the epidemiological patterns observed in France. Obtained results suggest that considering temporal changes in social factors in addition to demographic ones is critical to correctly interpret varicella transmission dynamics.

The impact of demographic changes, exogenous boosting and new vaccination policies on varicella and herpes zoster in Italy: a modelling and cost-effectiveness study

BackgroundThe present study aims to evaluate the cost-effectiveness of the newly introduced varicella and herpes zoster (HZ) vaccination programmes in Italy. The appropriateness of the introduction of the varicella vaccine is highly debated because of concerns about the consequences on HZ epidemiology and the expected increase in the number of severe cases in case of suboptimal coverage levels.MethodsWe performed a cost-utility analysis based on a stochastic individual-based model that considers realistic demographic processes and two different underlying mechanisms of exogenous boosting (temporary and progressive immunity). Routine varicella vaccination is given with a two-dose schedule (15 months, 5–6 years). The HZ vaccine is offered to the elderly (65 years), either alone or in combination with an initial catch-up campaign (66–75 years). The main outcome measures are averted cases and deaths, costs per quality-adjusted life years gained, incremental cost-effectiveness ratios, and net monetary benefits associated with the different vaccination policies.ResultsDemographic processes have contributed to shaping varicella and HZ epidemiology over the years, decreasing varicella circulation and increasing the incidence of HZ. The recent introduction of varicella vaccination in Italy is expected to produce an enduring reduction in varicella incidence and, indirectly, a further increase of HZ incidence in the first decades, followed by a significant reduction in the long term. However, the concurrent introduction of routine HZ vaccination at 65 years of age is expected to mitigate this increase and, in the longer run, to reduce HZ burden to its minimum. From an economic perspective, all the considered policies are cost-effective, with the exception of varicella vaccination alone when considering a time horizon of 50 years. These results are robust to parameter uncertainties, to the two different hypotheses on the mechanism driving exogenous boosting, and to different demographic projection scenarios.ConclusionsThe recent introduction of a combined varicella and HZ vaccination programme in Italy will produce significant reductions in the burden of both diseases and is found to be a cost-effective policy. This programme will counterbalance the increasing trend of zoster incidence purely due to demographic processes.

Universal varicella vaccination increased the incidence of herpes zoster in the child-rearing generation as its short-term effect

BackgroundEffects of universal varicella vaccination on the herpes zoster (HZ) incidence have not been elucidated. Universal varicella vaccination was introduced in Japan in October 2014. ObjectiveWe investigated the effects of universal varicella vaccination on HZ epidemiology. MethodsPatients with HZ have been monitored by the Miyazaki Dermatologist Society since 1997, and the effects of universal vaccination on the HZ incidences have been analyzed to determine which generation is most affected. ResultsThe number of HZ patients increased 1.54 times, and the gradual increase in the HZ incidence was observed in not only patients >60 years, but also other generations during the period from 1997 to 2017. The number of varicella patients was gradually reduced from 2010 to 2017 before introduction of universal varicella vaccination, and the HZ incidence in yearly change significantly increased from 2014 to 2016 in the total population associated with the significant decrease in varicella incidence. The HZ incidence significantly increased for individuals aged 20 to 49 years from 2014 to 2015 and most for individuals age 20–29 years (odds ratio [OR], 1.270; 95% confidence interval [CI], 1.071–1.505, P<0.001). We identified the child-rearing generation of age 20 to 49 years (OR, 1.270; 95% CI, 1.071–1.505, P<0.001) as the generation most influenced by universal varicella vaccination, when the HZ incidence increased gradually by approximately 2% per year. ConclusionsUniversal vaccination increased the HZ incidence in the child-rearing generation among the generations, possibly by reduced chance of boosting their immunity by exposure to varicella.

Effectiveness and impact of a single-dose vaccine against chickenpox in the community of Madrid between 2001 and 2015

ABSTRACTBackground: Chickenpox is a contagious airborne disease. Immunization by varicella vaccine is an effective preventive measure. The objective of this study is to evaluate the impact and effectiveness of a single-dose vaccination against chickenpox at 15 months of age.Methods: Observational study based on data from the Epidemiological Surveillance System of the Autonomous Community of Madrid from 2001 to 2015. The years were grouped into 4 periods according to epidemic cycles and vaccination schedule: 2001–06, 2007–10, 2011–13 and 2014–15. The impact was calculated as Relative Risk (RR) between the incidence of chickenpox in children between 15 months and 13 years of age between 2011–13 and 2001–06 through Poisson regression using notifications made to the Diseases of Compulsory Declaration (DCD) system, the Sentinel Physicians Network (SPN) and hospital discharge records noted as Minimum Basic Data Set (MBDS). The vaccine effectiveness (VE) was calculated using the screening method and a 1:2 case-control study paired by age and paediatrician in population from 15 months to 13 years and between 2007 and 2015 using SPN source data.Results: The RR2011–13/2001–06 using data from the DCD was 0.14 (95% CI: 0.14 to 0.15), 0.07 (95% CI: 0.06 to 0.08) from SPN and 0.17 (95% CI: 0.15 to 0.20) from MBDS. A total of 338 cases were included in the VE screening obtaining an overall of 93.1 (90.9 to 94.8). For a case-control study, 120 cases and 247 controls were recruited obtaining a VE of 92.4% (IC 95%: 80.8 to 97.0%).Conclusions: The single-dose vaccination against chickenpox at 15 months of age has high impact and effectiveness.

Evaluation of the effect of chickenpox vaccination on shingles epidemiology using agent-based modeling.

BackgroundBiological interactions between varicella (chickenpox) and herpes zoster (shingles), two diseases caused by the varicella zoster virus (VZV), continue to be debated including the potential effect on shingles cases following the introduction of universal childhood chickenpox vaccination programs. We investigated how chickenpox vaccination in Alberta impacts the incidence and age-distribution of shingles over 75 years post-vaccination, taking into consideration a variety of plausible theories of waning and boosting of immunity.MethodsWe developed an agent-based model representing VZV disease, transmission, vaccination states and coverage, waning and boosting of immunity in a stylized geographic area, utilizing a distance-based network. We derived parameters from literature, including modeling, epidemiological, and immunology studies. We calibrated our model to the age-specific incidence of shingles and chickenpox prior to vaccination to derive optimal combinations of duration of boosting (DoB) and waning of immunity. We conducted paired simulations with and without implementing chickenpox vaccination. We computed the count and cumulative incidence rate of shingles cases at 10, 25, 50, and 75 years intervals, following introduction of vaccination, and compared the difference between runs with vaccination and without vaccination using the Mann–Whitney U-test to determine statistical significance. We carried out sensitivity analyses by increasing and lowering vaccination coverage and removing biological effect of boosting.ResultsChickenpox vaccination led to a decrease in chickenpox cases. The cumulative incidence of chickenpox had dropped from 1,254 cases per 100,000 person-years pre chickenpox vaccination to 193 cases per 100,000 person-years 10 years after the vaccine implementation. We observed an increase in the all-ages shingles cumulative incidence at 10 and 25 years post chickenpox vaccination and mixed cumulative incidence change at 50 and 75 years post-vaccination. The magnitude of change was sensitive to DoB and ranged from an increase of 22–100 per 100,000 person-years at 10 years post-vaccination for two and seven years of boosting respectively (p < 0.001). At 75 years post-vaccination, cumulative incidence ranged from a decline of 70 to an increase of 71 per 100,000 person-years for two and seven years of boosting respectively (p < 0.001). Sensitivity analyses had a minimal impact on our inferences except for removing the effect of boosting.DiscussionOur model demonstrates that over the longer time period, there will be a reduction in shingles incidence driven by the depletion of the source of shingles reactivation; however in the short to medium term some age cohorts may experience an increase in shingles incidence. Our model offers a platform to further explore the relationship between chickenpox and shingles, including analyzing the impact of different chickenpox vaccination schedules and cost-effectiveness studies.

Management of chickenpox in pregnant women: an Italian perspective.

Chickenpox is a highly contagious disease caused by primary infection of varicella zoster virus (VZV). The disease is spread worldwide and is usually benign but, in some groups of population like pregnant women, can have a severe outcome. Due to a not optimal vaccination coverage, a relatively high number of childbearing-aged women in a European country such as Italy tested seronegative for VZV and so are currently at risk of acquiring chickenpox during pregnancy, especially if they live in contact with children for family or work reasons. Only few data are available about the risk of infection in this setting: the incidence of chickenpox may range from 1.5 to 4.6 cases/1000 childbearing females and from 1.21 to 6 cases/10,000 pregnant women, respectively. This review is aimed to focus on the epidemiology and the clinical management of exposure to chickenpox during pregnancy. Particular emphasis is given to the accurate screening of childbearing women at the time of the first gynecological approach — the females who tested susceptible to infection can be counseled about the risks and instructed on procedure should contact occur — and to the early prophylaxis of the at-risk exposure. Lastly, the achievement of adequate vaccination coverage of the Italian population remains a cornerstone in the prevention of chickenpox in pregnancy.

PSS30 - Modeling the Public Health Impact of Varicella Vaccination in Argentina: Implications of Vaccine Choice and Dosing Schedules

Argentina introduced one-dose universal varicella vaccination (UVV) in 2015. The objective of this study was to use a dynamic transmission model to evaluate both the impact of this programme and the implications of dosing schedules and vaccine characteristics on the short and long-term impact of UVV in a future two-dose schedule. We used the only available historical (1996) seroprevalence data from Argentina to calibrate a dynamic transmission model of varicella infection in a static population. In addition to the current one-dose UVV administered at 15 months, we considered two-dose UVV with different dosing intervals: short (15 and 18 months); medium (12 and 18 months); and long (15 months and 6 years). In all cases, we assumed coverage would be 90% with 1st dose and 85% with 2nd dose. We evaluated these scenarios considering two hypothetical varicella vaccines: a highly-effective vaccine with long duration of protection and a moderately-effective vaccine with shorter duration of protection. The estimated pre-vaccine varicella incidence of approximately 1,375 cases per 100,000 population per year will reduce to between 20-50 cases per 100,000 after two years of high-coverage (90%), single-dose UVV, depending on the vaccine used. Use of a two-dose UVV programme can prevent over 60 million varicella cases and 8,000 deaths over 100 years; the most effective programme is the short interval with the highly-effective vaccine, which prevents 500,000 cases and 52 deaths more than the least-effective programme (the moderately-effective vaccine with a long interval between doses). The differences in outcomes between the vaccines were most pronounced for long intervals between doses, and least pronounced for short intervals between doses. Two-dose UVV in Argentina has the potential to significantly reduce varicella incidence. Based on the historical seroprevalence data, a short or medium interval between doses with a highly-effective vaccine prevents the most disease.

PIN30 - The Economic Burden of Varicella in Mexico

To assess the clinical and economic burden of varicella in Mexico, where the varicella vaccine is not publicly available, except in children undergoing bone marrow transplantation. Annual societal costs were estimated for a base scenario by multiplying per-patient costs with varicella incidence from the Mexican epidemiological surveillance system (SUIVE), adjusted for the estimated proportion of public healthcare centers who do not regularly report. In a sensitivity analysis where cost calculations remained stable, epidemiological estimates ranged between raw SUIVE varicella rates (lower bound), and a 25% additive increment to reflect the estimated proportion of public sector patients who utilize private services (upper bound). Outcome Measures Clinical complications; health care resource utilization (HCRU)(frequency and type) including outpatient visits, allied healthcare contacts, doctor’s visits, tests/procedures performed, prescription and over-the-counter (OTC) medications, hospitalizations, and Emergency Room (ER) and Intensive Care Unit(ICU) visits/stays. Charts of 152 varicella patients were included, of which 75 and 77 were outpatients and inpatients [mean (SD) age=3.0 (3.2) and 2.6 (3.5) years, respectively]. Inpatients reported higher complication rates (inpatients vs. outpatients: 84.4% vs. 6.7%), prescription medication use (94.8% vs. 80.0%), over-the-counter medications use (71.4% vs. 80.0%), tests/procedures (87.0% vs. 5.3%), and allied health professional consultations (61.0% vs. 12.0%). Direct/indirect costs per case were $198/$42 (outpatients), and $5,633/$175 (inpatients). Estimated societal costs related to varicella ranged from $77-$218 million. Substantial clinical and associated public health and economic burden were observed among children with primary varicella infection in Mexico. These results highlight the need for implementation of a childhood varicella vaccination program.

Dynamic response of airborne infections to climate change: predictions for varicella

Characterizing how climate change will alter the burden of infectious diseases has clear public health implications. Despite our uniquely detailed understanding of the transmission process for directly transmitted immunizing infections, the impact of climate variables on these infections remains understudied. Here, we develop a novel approach that incorporates statistical analysis of climate effects with a mechanistic model of disease transmission, to investigate the dynamic response of directly transmitted, immunizing infections to climate change. We analyze the effect of climate on varicella, a common airborne childhood infection, by leveraging 30 years of reported cases across 32 states in Mexico. We use this to map the potential changes in the magnitude and variability of varicella incidence in Mexico as a result of predicted changes in future climate conditions. Our results indicate that the predicted decrease in relative humidity in Mexico towards the end of the century will increase incidence of varicella, all else equal. These changes in incidence will be non-uniform across the year such that cases will shift from winter to summer months. Climate-driven changes to the timing of future incidence, for these types of infections, may have substantial public health implications.