Validity of Reported Varicella History as a Marker for Varicella Zoster Virus Immunity Among Unvaccinated Children, Adolescents, and Young Adults in the Post-Vaccine Licensure Era
ABSTRACT We assessed the validity of reported varicella history as a marker for varicella zoster virus immunity among unvaccinated persons 1 to 29 years of age, and we examined varicella disease characteristics associated with varicella zoster virus immunity among those reporting positive histories.
We conducted a cross-sectional study at 7 community-based sites in Philadelphia, Pennsylvania, between June 2004 and May 2006 and recruited 1476 participants 1 to 29 years of age who had not been vaccinated against varicella. Sensitivity, specificity, and positive predictive value were determined by comparing self-reported or parent-reported varicella histories from a standardized study interview with varicella zoster virus immunoglobulin G serological results for each participant. We performed multivariate logistic regression analyses to determine which disease characteristics best predicted seropositivity.
The sensitivity of reported varicella history was highest (81%-89%) among participants > or =10 years of age, whereas specificity was highest among participants 1 to 4 years of age (99%) and > or =20 years (88%). Reported varicella history was highly predictive of seropositivity (>95%) only among participants > or =15 years of age. For participants 10 to 14 years of age, parental reports of a generalized itchy rash with 1 of the following were highly predictive of seropositivity: varicella transmission to another household member or being raised in a household with no other children. Among participants < or =9 years of age, no combination of disease characteristics was both highly predictive of seropositivity and common.
The validity of reported varicella history varies according to age, and a reported history is no longer highly predictive of seropositivity among cohorts born since 1994 (participants < or =9 years of age). Universal varicella vaccination, regardless of history, for these children should be considered, as should simplified criteria for varicella zoster virus immunity among unvaccinated persons born before 1994.
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ABSTRACT: Varicella exposure in health care settings poses a threat to susceptible, immunocompromised hosts. We describe the management and outcome of a varicella exposure in a neonatal intensive care unit. We reviewed the history of the index case, determination of the exposed cohort, medical management of exposed neonates, and assignment of health care workers based on exposure and immune status. We present the results of serologic testing of health care workers related to their history of varicella disease. Of 427 health care workers assessed at the time of the exposure, 13.1% were seronegative for varicella. Among 180 employees recorded as having a previous history of varicella, 9 were seronegative. A total of 34 infants received prophylaxis with intravenous immune globulin; acyclovir prophylaxis was added for those born at <28 weeks gestational age. The exposed cohort was isolated. No secondary cases of varicella occurred among patients or health care workers. Nosocomial varicella exposures require rapid assessment and response, which can be guided by a checklist of actions. Varicella immunity in health care workers cannot be assumed even among those born before 1980; institutional policies should adhere to the 2007 Centers for Disease Control and Prevention's definition of immunity to varicella for health care workers.American journal of infection control 05/2011; 39(10):844-8. DOI:10.1016/j.ajic.2011.02.006 · 2.33 Impact Factor
- Annals of Neurology 10/2011; 70(4):673-4; author reply 674. DOI:10.1002/ana.22605 · 11.91 Impact Factor
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ABSTRACT: OBJECTIVE: This paper examines how the monovalent varicella vaccine for children, with an adolescent catch-up dose, was introduced into Australia's National Immunisation Program (NIP), focusing on programme implementation. METHODS: Semi-structured interviews were conducted with key informants involved in programme implementation. Key themes from interviews were identified through content analysis. Childhood coverage was assessed using data from the Australian Childhood Immunisation Register (ACIR) with adolescent coverage obtained from state/territory immunisation programmes. Seroprevalence data were analysed from national serosurveys conducted before and after programme commencement. RESULTS: Implementation challenges for both parents and providers included: (a) parental report of previous infection as an exclusion criterion; (b) introducing a vaccine on its own at 18 months of age; and (c) adding the adolescent dose into existing school-based vaccination programmes with parental reported exclusion criteria. Despite these challenges, coverage rapidly reached 83% by 24 months of age and 30-33% for the adolescent catch-up dose. When considered in conjunction with estimated pre-vaccination natural immunity in both target groups (20% and 83%, respectively) coverage can be considered high. The serosurvey under-estimated coverage in 2-year-old children but was useful to assess trends in population immunity. CONCLUSION: The introduction of a single dose of monovalent varicella vaccine at 18 months of age and a school-based catch-up programme at 11-13 years of age successfully achieved high coverage, notwithstanding some challenges. Reported natural infection has been an exclusion criterion for vaccination, but as the programme matures and circulation of wild-type virus decreases, the need for this warrants consideration. There is a need for sensitive laboratory assays to measure vaccine-induced immunity at a population level.Vaccine 01/2013; 31(10). DOI:10.1016/j.vaccine.2012.12.052 · 3.49 Impact Factor