Italy implemented two-dose universal varicella vaccination (UVV) regionally from 2003 to 2013 and nationally from 2017 onwards. Our objective was to analyze regional disparities in varicella outcomes ...resulting from disparities in vaccine coverage rates (VCRs) projected over a 50-year time-horizon (2020-2070). A previously published dynamic transmission model was updated to quantify the potential public health impact of the UVV program in Italy at the national and regional levels. Four 2-dose vaccine strategies utilizing monovalent (V) and quadrivalent (MMRV) vaccines were evaluated for each region: (A) MMRV-MSD/MMRV-MSD, (B) MMRV-GSK/MMRV-GSK, (C) V-MSD/MMRV-MSD, and (D) V-GSK/MMRV-GSK. Costs were reported in 2022 Euros. Costs and quality-adjusted life-years (QALYs) were discounted 3% annually. Under strategy A, the three regions with the lowest first-dose VCR reported increased varicella cases (+ 34.3%), hospitalizations (+ 20.0%), QALYs lost (+ 5.9%), payer costs (+ 22.2%), and societal costs (+ 14.6%) over the 50-year time-horizon compared to the three regions with highest first-dose VCR. Regions with low first-dose VCR were more sensitive to changes in VCR than high first-dose VCR regions. Results with respect to second-dose VCR were qualitatively similar, although smaller in magnitude. Results were similar across all vaccine strategies.
Limited data are available on the contagiousness of vaccinated varicella cases.
To describe secondary attack rates within households according to disease history and vaccination status of the primary ...case and household contacts and to estimate varicella vaccine effectiveness.
Population-based, active varicella surveillance project in a community of approximately 320,000 in Los Angeles County, California, during 1997 and 2001. Varicella cases were reported by child care centers, private and public schools, and health care clinicians and were investigated to collect demographic, clinical, medical, and vaccination data. Information on household contacts' age, varicella history, and vaccination status was collected.
Varicella secondary attack rate among household contacts; vaccine effectiveness using secondary attack rates in unvaccinated and vaccinated children and adolescents.
A total of 6316 varicella cases were reported. Among children and adolescents aged 1 to 14 years, secondary attack rates varied according to age and by disease and vaccination status of the primary case and exposed household contacts. Among contacts aged 1 to 14 years exposed to unvaccinated cases, the secondary attack rate was 71.5% if they were unvaccinated and 15.1% if they were vaccinated (risk ratio RR, 0.21; 95% confidence interval CI, 0.15-0.30). Overall, vaccinated cases were half as contagious as unvaccinated cases. However, vaccinated cases with 50 lesions or more were similarly contagious as unvaccinated cases whereas those with fewer than 50 lesions were only one third as contagious (secondary attack rate, 23.4%; RR, 0.32 95% CI, 0.19-0.53). Vaccine effectiveness for prevention of all disease was 78.9% (95% CI, 69.7%-85.3%); moderate disease, 92% (50-500 lesions) and 100% (clinician visit); and severe disease, 100%.
Under conditions of intense exposure, varicella vaccine was highly effective in preventing moderate and severe disease and about 80% effective in preventing all disease. Breakthrough varicella cases in household settings were half as contagious as unvaccinated persons with varicella, although contagiousness varied with numbers of lesions.
Background Varicella zoster virus (VZV) is a neurotropic, exclusively human herpesvirus. Primary infection causes varicella (chickenpox), after which the virus becomes latent in ganglionic neurons ...along the entire neuraxis. As cell-mediated immunity to VZV declines with advancing age and immunosuppression, VZV reactivates to produce zoster (shingles). One of the most serious complications of zoster is VZV vasculopathy. Methods We reviewed recent studies of stroke associated with varicella and zoster, how VZV vasculopathy is verified virologically, vaccination to prevent varicella and immunization to prevent zoster, and VZV in giant cell arteritis (GCA). Findings We report recent epidemiological studies revealing an increased risk of stroke after zoster; the clinical, laboratory, and imaging features of VZV vasculopathy; that VZV vasculopathy is confirmed by the presence of either VZV DNA or anti-VZV IgG antibody in cerebrospinal fluid; special features of VZV vasculopathy in children; vaccination to prevent varicella and immunization to prevent zoster; and the latest evidence linking VZV to GCA. Conclusion In children and adults, VZV is a common cause of stroke.
Background. Vaccine-strain herpes zoster (HZ) can occur after varicella vaccination. This study determined the number and proportion of HZ cases caused by vaccine-strain varicella zoster virus (VZV), ...assessed the positive predictive value of provider diagnosis of HZ, and computed HZ incidence rates in vaccinated and unvaccinated children. Methods. We used electronic medical records to identify all office visits with an HZ diagnosis for children aged <18 years in a managed care plan. Providers collected skin specimens and completed a questionnaire. Specimens were tested by polymerase chain reaction to identify wild-type or vaccine-strain VZV. Results. From May 2005 to September 2009, we enrolled 322 subjects. VZV was detected in 82% of specimens (84% wild-type, 15% vaccine-strain, 1% possible vaccine-wild-type recombinant). Among the 118 vaccinated subjects, VZV was detected in 70% (52% wild-type). The positive predictive value for provider diagnosis of "definite HZ" was 93% for unvaccinated and 79% for vaccinated children. The incidence of laboratory-confirmed HZ was 48 per 100 000 person-years in vaccinated children (both wild-type and vaccine-strain) and 230 per 100 000 person-years in unvaccinated children (wild-type only). Conclusions. HZ incidence in vaccinated children was 79% lower than in unvaccinated children. Among vaccinated children, half of HZ cases were due to wild-type VZV.
Significant reductions in varicella incidence were reported from 1995 to 2000 in the varicella active surveillance sites of Antelope Valley (AV), California, and West Philadelphia (WP), Pennsylvania. ...We examined incidence rates, median age, and vaccination status of case patients for 1995–2005. Coverage data were from the National Immunization Survey. By 2005, coverage among children 19–35 months of age reached 92% (AV) and 94% (WP); 57% and 64% of case patients in AV and WP, respectively, were vaccinated; and varicella incidence declined by 89.8% in AV and 90.4% in WP. Incidence declined in all age groups, especially among children <10 years of age in both sites and among adolescents 10–14 years of age in WP. In AV, since 2000, the incidence among adolescents 10–14 and 15–19 years of age increased. Implementation of school requirements through 10th grade in WP may explain the differences in the decline in incidence among adolescents. Continued surveillance will be important to monitor the impact that the 2-dose vaccine policy in children has on varicella epidemiology.
•Evidencing the impact of the vaccine implementation in Argentina.•Describing the disease in the pre-vaccination era.•First monitoring of the post-vaccination era at the national scale.•Showing the ...performance of the vaccination program.
Varicella, also known as chickenpox is one of the most common immunizable diseases. In 1998, the World Health Organization (WHO) recommended to incorporate this vaccine in the national immunization programs, which Argentina did in 2015.
To describe the behavior of the varicella time series for the 2005–2017 period, and to evaluate the impact of the vaccine in Argentina.
An ecological observational study was performed, using the varicella cases reported in the National Health Monitoring System, and the data of the National census as secondary data sources. A model based time series analysis of the notified varicella cases in Argentina was performed, using a Negative Binomial Mixed Model. For the verification of the vaccine impact, the 2005–2014 period was selected, and a prognosis for the following years was performed. Impact was evaluated by comparing the rates and confidence intervals between the predicted and observed values.
Argentina reported 1,775,587 varicella cases for the 2005–2017 period. The series exhibited seasonality, and, a decreasing trend in the number of cases was observed in 2016 and 2017. A reduction of the incidence rate after the implementation of the vaccine was observed. The transmission risk decreased in the country after vaccine implementation.
This study is the first concrete evidence of the varicella incidence decline after the implementation of a single dose application program in Argentina.
Highlights ► In 2000, varicella incidence dramatically declined to 70% of the prevaccine rate. ► HZ reports significantly increased among adults aged 20–69 years from 2000 to 2001. ► Children with a ...prior history of varicella demonstrated HZ rates similar to adults. ► By 2002, the efficacy of the varicella vaccination had declined well below 80%. ► HZ morbidity costs have exceeded the cost savings from varicella-disease reductions.
Background. Live attenuated varicella vaccine is considered a safe vaccine with serious adverse effects reported only in immunocompromised children. We describe a severe life-threatening infection ...with varicella vaccine virus causing rash and pneumonitis in a 6-year-old boy with no apparent immunodeficiency. Methods and Results. Polymerase chain reaction (PCR) analysis of vesicle swab samples demonstrated varicella zoster virus (VZV). Sequencing of the PCR product demonstrated 100% homology with human herpesvirus 3 strain VZV-Oka ORF62 gene. Routine immunologic investigations failed to demonstrate any abnormality. Total leukocyte, lymphocyte, and neutrophil counts and lymphocyte subsets were normal. Immunoglobulins, C3, C4, and CH50 were intact. Specific IgG to protein and polysaccharide antigens and to Epstein-Barr virus and cytomegalovirus were present. Normal lymphocyte proliferation to phytohemagglutinin and VZV antigens was detected. Neutrophil function and natural killer (NK) cell activity were normal. The analysis of invariant NK T (iNKT) cell numbers and function revealed diminished iNKT cells, reported once previously and unique to our patient, deficient expression of the cognate receptor, CD1d. Conclusions. This report provides a further link between deficiency of the iNKT/CD1d pathway and increased susceptibility to varicella vaccine virus, suggesting an important role of this innate pathway in host defense against yet another member of the herpesvirus family.
BackgroundVaricella can be a severe illness in human immunodeficiency virus (HIV)–infected children. The licensed, live attenuated varicella vaccine is safe and immunogenic in HIV-infected children ...with minimal symptoms and good preservation of CD4+ T cells (Centers for Disease Control and Prevention immunologic category 1) MethodsTo study the safety and immunogenicity of this vaccine in varicella-zoster virus (VZV)–naive, HIV-infected children with moderate symptoms and/or more pronounced past or current decreases in CD4+ T cell counts, such children (age, 1–8 years) received 2 doses of vaccine 3 months apart. The children were observed in a structured fashion for adverse events. Blood was tested for VZV antibody and VZV-specific cell-mediated immunity (CMI) at baseline, 8 weeks after each dose, and annually for 3 years. Subjects who had no evidence of immunity 1 year after vaccination received a third dose and were retested ResultsThe vaccine was well tolerated; there were no vaccine-related, serious adverse events. Regardless of immunologic category, at least 79% of HIV-infected vaccine recipients developed VZV-specific antibody and/or CMI 2 months after 2 doses of vaccine, and 83% were responders 1 year after vaccination ConclusionsHIV-infected children with a CD4+ T cell percentage of ⩾15% and a CD4+ T cell count of ⩾200 cells/μL are likely to benefit from receiving varicella vaccine
•Even with high coverage, single-dose varicella vaccine is insufficient to prevent school outbreaks.•The proportion of breakthrough varicella cases among all outbreak-related cases showed an ...increasing trend from 2008 to 2017.•The administration of varicella vaccine as post-exposure prophylaxis is an appropriate intervention for varicella outbreak control.
To investigate varicella outbreak trends among schoolchildren during the voluntary single-dose varicella vaccine (VarV) era in Shanghai, China.
Trends in school varicella outbreaks from 2006 to 2017 were assessed using joinpoint regression models. The impacts of changes in single-dose VarV coverage among schoolchildren and implementation of post-exposure prophylaxis (PEP) strategies on outbreak trends were further analyzed.
In total, 265 varicella outbreaks involving 3263 cases were reported in Shanghai from 2006 to 2017. The number of outbreaks showed an increasing trend from 2006 to 2017 (t=2.62, p=0.026), especially in kindergartens. The proportion of breakthrough varicella cases among all outbreak-related cases showed an increasing trend from 30.4% in 2008 to 85.7% in 2017 (t=7.45, p<0.001). Single-dose VarV coverage among schoolchildren was 88.1%, and showed a significant increase from the 1996 to the 2008 birth cohorts, followed by a non-significant decline from the 2008 to the 2014 birth cohorts. During school outbreaks in which PEP campaigns were conducted, the varicella attack rate was significantly lower than those in outbreaks without PEP campaigns (1.2% vs. 1.4%; Chi-square=23.35, p<0.001).
Even with high coverage, single-dose VarV is insufficient to prevent school outbreaks. The administration of VarV as PEP is an appropriate intervention for varicella outbreak control prior to implementing a two-dose VarV schedule.
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