BACKGROUND: A second dose of varicella vaccine was recommended for U.S. children in 2006. We investigated a suspected varicella outbreak in School District X, Texas to determine 2-dose varicella vaccine effectiveness (VE). METHODS: A varicella case was defined as an illness with maculopapulovesicular rash without other explanation with onset during April 1-June 10, 2011, in a School District X student. We conducted a retrospective cohort in the two schools with the majority of cases. Lesion, saliva, and environmental specimens were collected for varicella-zoster virus (VZV) PCR testing. VE was calculated using historic attack rates among unvaccinated. RESULTS: In School District X, 82 varicella cases were reported, including 60 from Schools A and B. All cases were mild, with a median of 14 lesions. All 10 clinical specimens and 58 environmental samples tested negative for VZV. Two-dose varicella vaccination coverage was 66.4% in Schools A and B. Varicella VE in affected classrooms was 80.9% (95% CI: 67.2-88.9) among 1-dose vaccinees and 94.7% (95% CI: 89.2-97.4) among 2-dose vaccinees in School A, with a second dose incremental VE of 72.1% (95% CI: 39.0-87.3). Varicella VE among School B students did not differ significantly by dose (80.1% vs. 84.2% among 1-dose and 2-dose vaccinees, respectively). CONCLUSION: Laboratory testing could not confirm varicella as the etiology of this outbreak; clinical and epidemiologic data suggests varicella as the likely cause. Better diagnostics are needed for diagnosis of varicella in vaccinated individuals so that appropriate outbreak control measures can be implemented. Published by Elsevier Ltd.
BACKGROUND: A second dose of varicella vaccine was recommended for U.S. children in 2006. We investigated a suspected varicella outbreak in School District X, Texas to determine 2-dose varicella vaccine effectiveness (VE). METHODS: A varicella case was defined as an illness with maculopapulovesicular rash without other explanation with onset during April 1-June 10, 2011, in a School District X student. We conducted a retrospective cohort in the two schools with the majority of cases. Lesion, saliva, and environmental specimens were collected for varicella-zoster virus (VZV) PCR testing. VE was calculated using historic attack rates among unvaccinated. RESULTS: In School District X, 82 varicella cases were reported, including 60 from Schools A and B. All cases were mild, with a median of 14 lesions. All 10 clinical specimens and 58 environmental samples tested negative for VZV. Two-dose varicella vaccination coverage was 66.4% in Schools A and B. Varicella VE in affected classrooms was 80.9% (95% CI: 67.2-88.9) among 1-dose vaccinees and 94.7% (95% CI: 89.2-97.4) among 2-dose vaccinees in School A, with a second dose incremental VE of 72.1% (95% CI: 39.0-87.3). Varicella VE among School B students did not differ significantly by dose (80.1% vs. 84.2% among 1-dose and 2-dose vaccinees, respectively). CONCLUSION: Laboratory testing could not confirm varicella as the etiology of this outbreak; clinical and epidemiologic data suggests varicella as the likely cause. Better diagnostics are needed for diagnosis of varicella in vaccinated individuals so that appropriate outbreak control measures can be implemented. Published by Elsevier Ltd.
Authors: Jessica Leung; Adriana S Lopez; Joel Blostein; Nancy Thayer; Jennifer Zipprich; Anna Clayton; Vicki Buttery; Jannifer Andersen; Carrie A Thomas; Maria Del Rosario; Kurt Seetoo; Tracy Woodall; Rachel Wiseman; Stephanie R Bialek Journal: Pediatr Infect Dis J Date: 2015-10 Impact factor: 2.129
Authors: Peter Wutzler; Paolo Bonanni; Margaret Burgess; Anne Gershon; Marco Aurélio Sáfadi; Giacomo Casabona Journal: Expert Rev Vaccines Date: 2017-07-13 Impact factor: 5.217
Authors: Stephanie R Bialek; Dana Perella; John Zhang; Laurene Mascola; Kendra Viner; Christina Jackson; Adriana S Lopez; Barbara Watson; Rachel Civen Journal: Pediatrics Date: 2013-10-07 Impact factor: 7.124
Authors: Carrie A Thomas; Thein Shwe; Dee Bixler; Maria del Rosario; Scott Grytdal; Chengbin Wang; Loretta E Haddy; Stephanie R Bialek Journal: Pediatr Infect Dis J Date: 2014-11 Impact factor: 2.129