Younger Age at Vaccination May Increase Risk of Varicella Vaccine Failure

Galil, Karin; Fair, Elizabeth; Mountcastle, Norine; Britz, Phyllis; Seward, Jane F.

doi:10.1086/341089

Cited by 105 publications

(95 citation statements)

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“…In open-label prelicensure studies in which efficacy was calculated by using historical attack rates for comparison, the efficacy of 1 dose of the varicella vaccine that ultimately was licensed most commonly ranged from 70% to 90% against infection and 95% against severe disease. [65][66][67] In general, postlicensure effectiveness studies have reported a similar range for prevention against infection, 16,[68][69][70][71][72][73] with a few studies yielding lower 17,70 or higher 68 values. The vaccine is highly effective (Ն97%) in preventing severe varicella in postlicensure evaluations.…”

Section: Efficacy and Effectivenessmentioning

confidence: 98%

Prevention of Varicella: Recommendations for Use of Varicella Vaccines in Children, Including a Recommendation for a Routine 2-Dose Varicella Immunization Schedule

Bocchini¹,

Baltimore²,

Bernstein³

et al. 2007

Pediatrics

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National varicella immunization coverage using the current 1-dose immunization strategy has increased among vaccine-eligible children 19 through 35 months of age from 27% in 1997 to 88% by 2005. These high immunization rates have resulted in a 71% to 84% decrease in the reported number of varicella cases, an 88% decrease in varicella-related hospitalizations, a 59% decrease in varicellarelated ambulatory care visits, and a 92% decrease in varicella-related deaths in 1-to 4-year-old children when compared with data from the prevaccine era. Despite this significant decrease, the number of reported cases of varicella has remained relatively constant during the past 5 to 6 years. Since vaccine effectiveness for prevention of disease of any severity has been 80% to 85%, a large number of cases of varicella continue to occur among people who already have received the vaccine (breakthrough varicella), and outbreaks of varicella have been reported among highly immunized populations of schoolchildren. The peak age-specific incidence has shifted from 3-to 6-year-old children in the prevaccine era to 9-to 11-year-old children in the postvaccine era for cases in both immunized and unimmunized children during these outbreaks. Outbreaks of varicella are likely to continue with the current 1-dose immunization strategy.After administration of 2 doses of varicella vaccine in children, the immune response is markedly enhanced, with Ͼ99% of children achieving an antibody concentration (determined by glycoprotein enzyme-linked immunosorbent assay) of Ն5 U/mL (an approximate correlate of protection) and a marked increase in geometric mean antibody titers after the second vaccine dose. The estimated vaccine efficacy over a 10-year observation period of 2 doses for prevention of any varicella disease is 98% (compared with 94% for 1 dose), with 100% efficacy for prevention of severe disease. Recipients of 2 doses of varicella vaccine are 3.3-fold less likely to have breakthrough varicella, compared with those who are given 1 dose, during the first 10 years after immunization.To achieve greater levels of immunity with fewer serosusceptible people, greater protection against breakthrough varicella disease, and reduction in the number of outbreaks that occur nationwide among school-aged populations, a 2-dose varicella immunization strategy is now recommended for children Ն12 months of age. All clinical reports from the American Academy of Pediatrics automatically expire 5 years after publication unless reaffirmed, revised, or retired at or before that time.The guidance in this report does not indicate an exclusive course of treatment or serve as a standard of medical care. Variations, taking into account individual circumstances, may be appropriate.

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Section: Efficacy and Effectivenessmentioning

confidence: 98%

Prevention of Varicella: Recommendations for Use of Varicella Vaccines in Children, Including a Recommendation for a Routine 2-Dose Varicella Immunization Schedule

Bocchini¹,

Baltimore²,

Bernstein³

et al. 2007

Pediatrics

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“…Considering the age of participants in the studies and vaccine recommendations in each country, the median time since vaccination is likely lower than 10 years. Within this time frame, some studies described a higher risk for vaccine failure with time since vaccination (using a cutoff of 3, 4, or 5 years), 22,26,28,[34][35][36] but other studies did not find this association 27,[37][38][39][40][41] ; in all these studies, conducted during outbreak investigations, the sample sizes were usually insufficient to assess the independent effect of time since vaccination as a risk factor. Four studies reported decline in VE with time since vaccination; however, the differences did not reach statistical significance.…”

Section: Figurementioning

confidence: 99%

Global Varicella Vaccine Effectiveness: A Meta-analysis

et al. 2016

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CONTEXT: Several varicella vaccines are available worldwide. Countries with a varicella vaccination program use 1-or 2-dose schedules. OBJECTIVE:We examined postlicensure estimates of varicella vaccine effectiveness (VE) among healthy children.DATA SOURCES: Systematic review and descriptive and meta-analysis of Medline, Embase, Cochrane libraries, and CINAHL databases for reports published during 1995-2014. STUDY SELECTION:Publications that reported original data on dose-specific varicella VE among immunocompetent children. DATA EXTRACTION:We used random effects meta-analysis models to obtain pooled one dose VE estimates by disease severity (all varicella and moderate/severe varicella). Within each severity category, we assessed pooled VE by vaccine and by study design. We used descriptive statistics to summarize 1-dose VE against severe disease. For 2-dose VE, we calculated pooled estimates against all varicella and by study design. RESULTS:The pooled 1-dose VE was 81% (95% confidence interval [CI]: 78%-84%) against all varicella and 98% (95% CI: 97%-99%) against moderate/severe varicella with no significant association between VE and vaccine type or study design (P > .1). For 1 dose, median VE for prevention of severe disease was 100% (mean = 99.4%). The pooled 2-dose VE against all varicella was 92% (95% CI: 88%-95%), with similar estimates by study design.LIMITATIONS: VE was assessed primarily during outbreak investigations and using clinically diagnosed varicella. CONCLUSIONS:One dose of varicella vaccine was moderately effective in preventing all varicella and highly effective in preventing moderate/severe varicella, with no differences by vaccine. The second dose adds improved protection against all varicella.a National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia; and b Department of Immunization, Vaccines and Biologicals, World Health Organization, Geneva, Switzerland Dr Marin conceptualized and designed the study, reviewed the articles and collected the data, supervised the analysis, interpreted the data, drafted the initial manuscript, and revised the manuscript; Dr Marti conceptualized the study, reviewed part of the articles, interpreted the data, and reviewed and revised the manuscript; Ms Kambhampati carried out the meta-analyses, interpreted the data, and reviewed the manuscript; Dr Jeram conducted an initial literature review, reviewed part of the articles and collected the data, and reviewed the manuscript; Dr Seward conceptualized and designed the study, reviewed part of the articles, critically reviewed the manuscript, and interpreted the data; and all authors approved the fi nal manuscript as submitted.The fi ndings and conclusions in this report are those of the authors and do not necessarily represent the offi cial position of the Centers for Disease Control and Prevention. For authors affi liated with the World Health Organization, the authors alone are responsible for the views expressed in this publication ...

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“…A CDC-sponsored study to examine the rate of seroconversion in VZV-vaccinated asthmatic children, as determined by FAMA, is currently under way in the United States. A number of completed studies show higher rates of breakthrough varicella in children vaccinated before 15 months of age, possibly reflecting a higher risk of primary vaccine failure in this age group (35,43). When varicella vaccine is administered less than 1 month after another live vaccine, the incidence of breakthrough varicella may also increase (24).…”

Section: Controversies Regarding Varicella Vaccinementioning

confidence: 99%

Preventing Varicella-Zoster Disease

2005

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Varicella-zoster virus (VZV), the cause of chickenpox and shingles, is a pathogen in retreat following the introduction of mass vaccination in the United States in 1995. The live attenuated Oka vaccine, which is safe and immunogenic, gives good protection against both varicella and zoster in the short to medium term. It has undoubtedly been highly effective to date in reducing all forms of varicella, especially severe disease. However, the huge pool of latent wild-type virus in the population represents a continuing threat. Both the biology and the epidemiology of VZV disease suggest that new vaccination strategies will be required over time

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Younger Age at Vaccination May Increase Risk of Varicella Vaccine Failure

Cited by 105 publications

References 8 publications

Prevention of Varicella: Recommendations for Use of Varicella Vaccines in Children, Including a Recommendation for a Routine 2-Dose Varicella Immunization Schedule

Prevention of Varicella: Recommendations for Use of Varicella Vaccines in Children, Including a Recommendation for a Routine 2-Dose Varicella Immunization Schedule

Global Varicella Vaccine Effectiveness: A Meta-analysis

Preventing Varicella-Zoster Disease

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