Burden of varicella in Central and Eastern Europe: findings from a systematic literature review

The Clinical and Economic Burden of Antibiotic Use in Pediatric Patients With Varicella Infection: A Retrospective Cohort Analysis of Real-World Data in England

BACKGROUND

Varicella is a highly infectious disease, particularly affecting children, that can lead to complications requiring antibiotics or hospitalization. Antibiotic use for varicella management is poorly documented. This study assessed antibiotic use for varicella and its complications in a pediatric population in England.

METHODS

Data were drawn from medical records in the Clinical Practice Research Datalink and Hospital Episode Statistics data sets. The study included patients <18 years old with varicella diagnosed during 2014-2018 and 3-month follow-up available. We determined varicella-related complications, medication use, healthcare resource utilization, and costs from diagnosis until 3 months after diagnosis.

RESULTS

We identified 114 578 children with a primary varicella diagnosis. Of these, 7.7% (n = 8814) had a varicella-related complication, the most common being ear, nose, and throat related (37.1% [n = 3271]). In all, 25.9% (n = 29 706 of 114 578) were prescribed antibiotics. A higher proportion of patients with complications than without complications were prescribed antibiotics (64.3% [n = 5668 of 8814] vs 22.7% [n = 24 038 of 105 764]). Mean annualized varicella-related costs were £2 231 481 for the study cohort. Overall, antibiotic prescriptions cost approximately £262 007.

CONCLUSIONS

This study highlights high antibiotic use and healthcare resource utilization associated with varicella management, particularly in patients with complications. A national varicella vaccination program in England may reduce varicella burden and related complications, medication use, and costs.

A hidden dilemma; post COVID-19 first detection of Varicella zoster M4 genotype from Pakistan

OBJECTIVES

During the COVID-19 pandemic, the risk of childhood infectious diseases was increased. Post-COVID-19 escalation of chickenpox cases, becoming an emerging public health concern. Thus, the study was designed to compare chickenpox prevalence and Varicella zoster virus (VZV) genotypes circulating before, during, and post-COVID-19 in Pakistan.

METHODS

A total of 267 lesion specimens collected from tertiary care hospitals, and chickenpox outbreaks from Pakistan were analysed by a two-amplicon approach with phylogenetic analysis.

RESULTS

Among suspected cases, overall 178/267 were VZV positive. Majority (84.2 %; 150/178) cases were of post-COVID-19 pandemic time. Small outbreaks occurred soon after COVID-19 in Rawalpindi and Islamabad (Pakistan), 40 positive cases out of 178 cases were outbreak cases. There was first time detection of the M4 genotype, which was significantly associated with disease severity (p = 0.0006) and post-COVID-19 chickenpox outbreaks in 2021 (77.9 %; 46/59; p < 0.00001). However, in pre-COVID-19 only M2 genotype was detected. The M2 prevalence varied from 2019 (100 %; 19/19) to 2022 (3.2 %; 3/91). However, the most prevalent strain of 2022 belonged to the M1 genotype (64.8 %; 59/91).

CONCLUSION

A significant rise in chickenpox cases detected soon after COVID-19 in Pakistan, and oscillation of different VZV genotypes with first time detection of M4 genotype is an alarming situation. This demands further detailed genotypic studies on transmission dynamics of a rare M4 with other genotypes to protect the local population and restrict spread in other regions.

Clinical and Economic Burden of Antibiotic Use Among Pediatric Patients With Varicella Infection in the Outpatient Setting: A Retrospective Cohort Analysis of Real-world Data in France

BACKGROUND

Varicella infects 90% of children before age 9. Though varicella is self-limiting, its complications may require antibiotics, though how antibiotics are utilized for varicella in France is not well known. This study assessed antibiotic use and costs associated with varicella and its complications in pediatric patients managed in the outpatient setting in France.

METHODS

A retrospective cohort study using the Cegedim Strategic Data-Longitudinal Patient Database, an electronic medical record database from general practitioners and office-based specialists in France, was conducted. Children <18 years old diagnosed with varicella between January 2014 and December 2018 with 3-month follow-up available were included. We used descriptive analysis to assess varicella-related complications, medication use, healthcare resource utilization and costs.

RESULTS

Overall, 48,027 patients were diagnosed with varicella; 15.3% (n = 7369) had ≥1 varicella-related complication. Antibiotics were prescribed in up to 25.1% (n = 12,045/48,027) of cases with greater use in patients with complications (68.1%, n = 5018/7369) compared with those without (17.3%, n = 7027/40,658). Mean medication and outpatient varicella-related costs were €32.82 per patient with medications costing a mean of €5.84 per patient; antibiotics contributed ~23% to total costs annually.

CONCLUSION

This study showed high antibiotic use for the management of varicella and its complications. A universal varicella vaccination program could be considered to alleviate complications and associated costs in France.

Chickenpox Outbreaks in Three Refugee Camps on Mainland Greece, 2016-2017: A Retrospective Study

INTRODUCTION

Displaced populations face disproportionately high risk of communicable disease outbreaks given the strains of travel, health care circumstances in their country of origin, and limited access to health care in receiving countries.

STUDY OBJECTIVE

Understanding the role of demographic characteristics in outbreaks is important for timely and efficient control measures. Accordingly, this study assesses chickenpox outbreaks in three large refugee camps on mainland Greece from 2016 - 2017, using clinical line-list data from Médecins du Monde (MdM) clinics.

METHODS

Clinical line-list data from MdM clinics operating in Elliniko, Malakasa, and Raidestos camps in mainland Greece were used to characterize chickenpox outbreaks in these camps. Logistic regression was used to compare the odds of chickenpox by sex, camp, and yearly increase in age. Incidences were calculated for age categories and for sex for each camp outbreak.

RESULTS

Across camps, the median age was 19 years (IQR: 7.00 - 30.00 years) for all individuals and five years (IQR: 2.00 - 8.00 years) for cases. Males were 55.94% of the total population and 51.32% of all cases. There were four outbreaks of chickenpox across Elliniko (n = 1), Malakasa (n = 2), and Raidestos (n = 1) camps. The odds of chickenpox when controlling for age and sex was lower for Malakasa (OR = 0.46; 95% CI, 0.38 - 0.78) and Raidestos (OR = 0.36; 95% CI, 0.24 - 0.56) when compared Elliniko. Odds of chickenpox were comparable between Malakasa and Raidestos (OR = 1.49; 95% CI, 0.92 - 2.42). Across all camps, the highest incidence was among children zero-to-five years of age. The sex-specific incidence chickenpox was higher for males than females in Elliniko and Malakasa, while the incidence was higher among females in Raidestos.

CONCLUSION

As expected, individuals five years of age and under made up the majority of chickenpox cases. However, 12% of cases were teenagers or older, highlighting the need to consider atypical age groups in vaccination strategies and control measures. To support both host and displaced populations, it is important to consider risk-reduction needs for both groups. Including host communities in vaccination campaigns and activities can help reduce the population burden of disease for both communities.

Clinical efficacy and effectiveness of alternative varicella vaccination strategies: An overview of reviews

A number of countries have implemented universal childhood varicella vaccination programmes over the past 30 years. However, strategies differ in terms of dosing schedule (one- or two-dose), type of vaccine(s) recommended (monovalent, quadrivalent measles-mumps-rubella-varicella, or both), age at vaccination, and dosing interval for a two-dose schedule. An overview of reviews was undertaken to assess the existing systematic review evidence of the clinical efficacy/effectiveness of alternative varicella vaccination strategies. A comprehensive search of databases, registries and grey literature was conducted up to 2 February 2022. Two reviewers independently screened, extracted data and assessed the methodological quality of included reviews. A total of 20 reviews were included in the overview; 17 assessed the efficacy/effectiveness of one-dose strategies and 10 assessed the efficacy/effectiveness of two-dose strategies. Although the quality of most reviews was deemed 'critically low', there was clear and consistent evidence that vaccination is very effective at reducing varicella. While the analysis was restricted due to lack of detail in reporting of the reviews, the evidence suggests that two-dose strategies are more efficacious/effective than one-dose strategies in preventing varicella of any severity, but that both strategies have similar high efficacy/effectiveness in preventing moderate or severe varicella. Based on this evidence in this overview of reviews, a key consideration for policymakers on the possible introduction of a childhood varicella vaccination programme and the choice between a one- or two-dose strategy, will be whether the objective of a programme is to prevent varicella of any severity or to prevent moderate to severe varicella.

The Long-Term Clinical and Economic Impact of Universal Varicella Vaccination in Slovenia

Background: Despite the substantial burden of varicella infection, Slovenia does not currently have a universal varicella vaccination (UVV) program. We modeled the long-term clinical and economic impact of implementing 2-dose UVV strategies compared with no vaccination in Slovenia. Methods: A previously published dynamic transmission model was adapted to the demographics, varicella seroprevalence, herpes zoster incidence, and contact patterns in Slovenia. Six 2-dose UVV strategies, vs no vaccination, were considered over a 50-year period, including monovalent vaccination (Varivax® [V-MSD] or Varilrix® [V-GSK]) at ages 12 and 24 months, or monovalent vaccination at 15 months followed by monovalent or quadrivalent vaccination (ProQuad® [MMRV-MSD] or Priorix- Tetra® [MMRV-GSK]) at 5.5 years. Costs, quality-adjusted life-years, and incremental cost-effectiveness ratios vs no vaccination were calculated to assess the economic impact of each strategy from payer and societal perspectives. Results: The incidence of varicella infection was estimated as 1228 per 100 000 population in the absence of UVV. Over 50 years, depending on vaccination strategy, UVV reduced varicella cases by 77% to 85% and was associated with substantial reductions in varicella deaths (39%-44%), outpatient cases (74%-82%), and hospitalizations (74%-82%). The greatest reductions were predicted with V-MSD (15 months/5.5 years) and V MSD/MMRV-MSD (15 months/5.5 years). Discussion: All 2-dose UVV strategies were cost-effective compared with no vaccination from payer and societal perspectives, with V-MSD (15 months/5.5 years) being the most favorable from both perspectives. Conclusion: Policymakers should consider implementing UVV to reduce the burden of varicella disease in Slovenia.

Randomised controlled trial showed long-term efficacy, immunogenicity and safety of varicella vaccines in Norwegian and Swedish children

AIM

Several countries, such as Norway and Sweden, have not implemented universal varicella vaccination. We present data for Norway and Sweden that were generated by a paediatric multi-country Phase III study over a 10-year period. This assessed the efficacy, antibody persistence and safety of two varicella vaccines containing the same Oka strain.

METHODS

This was an observer-blind, controlled trial conducted in 10 European countries. Children aged 12-22 months (n = 5803) were randomised 3:3:1 and vaccinated between 1 September 2005 and 10 May 2006. The two-dose group received two tetravalent measles-mumps-rubella-varicella vaccine doses. The one-dose group received one monovalent varicella vaccine dose after a measles-mumps-rubella vaccine dose. Control group participants received two measles-mumps-rubella vaccine doses. Main study outcomes were vaccine efficacy against confirmed varicella cases and incidence of adverse events.

RESULTS

Vaccine efficacy in the two-dose group was ≥92.1% in both Norwegian and Swedish children compared to 72.3% in Norway and 58.0% in Sweden in the one-dose group. Incidences of adverse events and serious adverse events were similar in the Norwegian and Swedish study populations.

CONCLUSION

Consistent with overall study results, high efficacy against varicella and acceptable safety profiles of the two varicella vaccines were observed in Norwegian and Swedish populations. These findings highlight the benefits of varicella vaccines, particularly when administered as a two-dose schedule.

Phase 3, open-label, Russian, multicenter, single-arm trial to evaluate the immunogenicity of varicella vaccine (VARIVAX™) in healthy infants, children, and adolescents

Varicella (chickenpox) is a common, highly contagious disease caused by primary infection with varicella zoster virus (VZV), which can result in bacterial superinfection, central nervous system complications, and hospitalization. Stage 2 of this Phase 3 open-label study (ClinicalTrials.gov identifier: NCT03843632) enrolled 100 healthy infants, children, and adolescents (12 months–6 years, n = 37; 7–12 years, n = 33; 13–17 years, n = 30) without a clinical history of varicella. Participants aged 12 months–12 years were administered 1 dose of VARIVAX™ 0.5 mL (Varicella Virus Vaccine Live [Oka/Merck]) and adolescents aged 13–17 years were administered 2 doses 6 weeks apart. For participants seronegative at baseline (VZV antibody titer <1.25 glycoprotein enzyme-linked immunosorbent assay [gpELISA] units/mL), immunogenicity was assessed by seroconversion (VZV antibody titer ≥5 gpELISA units/mL) and VZV antibody geometric mean titers 6 weeks after the final dose. For participants who were VZV seropositive at baseline (VZV antibody titer ≥1.25 gpELISA units/mL), immunogenicity was assessed by antibody titer geometric mean fold rise and percentage of participants with ≥4-fold rise in antibody titer 6 weeks after the final dose. A Vaccine Report Card was used to report solicited and unsolicited adverse events through 42 days post-vaccination. After series completion among seronegative participants across age groups (n = 74), 98.6% demonstrated seroconversion 6 weeks post-vaccination; among seropositive participants (n = 26), 65.4% had ≥4-fold rise in antibody titer 6 weeks post-vaccination. No new safety signals were observed. Administering VARIVAX to infants, children, and adolescents resulted in an acceptable immune response with a safety profile consistent with the licensed product.

Phase 3, open-label, Russian, multicenter, single-arm trial to evaluate the immunogenicity of varicella vaccine (VARIVAX™) in healthy adults

Varicella (chickenpox) is a common, highly contagious disease caused by primary infection with varicella zoster virus (VZV). Adults typically experience more severe symptoms than children and have a higher risk of developing complications. Stage 1 of this Phase 3 open-label study enrolled healthy adults in Russia aged 18-75 years without a clinical history of varicella infection. Eligible participants (n = 50) were administered 2 doses of VARIVAX™ (Varicella Virus Vaccine Live [Oka/Merck]) 0.5 mL 6 weeks apart. For participants seronegative at baseline (VZV antibody titer <1.25 glycoprotein enzyme-linked immuno-sorbent assay [gpELISA] units/mL), immunogenicity was assessed by seroconversion (VZV antibody titer ≥5 gpELISA units/mL) and assessment of geometric mean titers of VZV antibody as measured by gpELISA 6 weeks after Dose 2. For VZV seropositive participants at baseline (VZV antibody titer ≥1.25 gpELISA units/mL), immunogenicity was assessed by geometric mean fold rise in antibody titer and percentage of participants with a ≥ 4-fold rise in antibody titer 6 weeks after Dose 2. A Vaccine Report Card was used to record solicited and unsolicited adverse events through 42 days post-vaccination. All participants who were seronegative (n = 26) at baseline demonstrated seroconversion 6 weeks after Dose 2. Among participants who were seropositive at baseline (n = 23), 60.9% had a ≥4-fold rise in antibody titer 6 weeks after Dose 2. Vaccination was generally well tolerated, with no new safety signals identified. Administration of 2 doses of VARIVAX in adults in Russia results in acceptable immune responses with safety data consistent with the licensed product (Clinicaltrials.gov identifier: NCT03843632).

Complications of Chickenpox in Bulgaria – Data from a Single-Center Experience

Primary Varicella zoster infection (chickenpox) in childhood is a common benign disease. The predominance of uncomplicated cases in children often overshadows the rarer cases of complicated severe course of the disease.

Objective

To study the complications of primary chickenpox in hospitalized patients for a period of one year.

Materials and Methods

122 patients with complicated primary chickenpox with an average age of 18.6 years; 57 males (46.7%) and 64 females (53.3%), were hospitalized at the University Hospital of Infectious and Parasitic Diseases “Prof. Iv. Kirov” in the period January – December 2019.

Results

The bacterial infections of the skin and soft tissues comprised the largest relative frequenchy – they occurred in 74 (60.6%) of the patients; followed by pneumonia – in 31 (25.4%) patients, and a combination of pneumonia and pustulation – in 10 (8.2%) patients. Cerebelitis was observed in 1 (0.8%) patient. One of the patients developed hepatitis, purulent arthritis and acute enteritis. We also report the death of one patient.

Conclusions

We registered a relatively high proportion of hospitalizations, especially in young children and adults. Regarding the type of complications, we do not describe significant differences compared to other authors. Although in most cases primary chickenpox is a self-limiting disease, complications are more common in the countries where there is no vaccine.

Acceptance of varicella vaccination

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.

Attitudes towards varicella vaccination in parents and paediatric healthcare providers in Hungary

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Seasonal dynamics of varicella incidence in Bulgaria

Aim: Spatial and temporal distribution of varicella is heterogenic and insufficiently studied in Europe. The present study tries to fill the gap that exists about the seasonality of the infection in Bulgaria. Materials & methods: A 4-year retrospective study of the monthly and seasonal varicella epidemiology was performed at both national and district level. Results: In Bulgaria, varicella incidence peaked during winter (37% of the 2015–2018 cases), followed by spring (33%) and autumn (23%). Highly populated districts were more likely to follow this pattern, while less inhabited districts with smaller urbanized areas showed different periodicity of the infection. Conclusion: Winter peak in varicella incidence is positively associated with high accumulation of people in the large cities (>75,000 inhabitants).