The Epidemiology of Varicella Disease in New York City, Janelle A. Anderson, MPH CDC/CSTE Applied Epidemiology Fellow New York City Department of Health and Mental Hygiene

Overview Varicella –Disease –Complications –Vaccine Data sources Methods Results Conclusions

Varicella Acute infectious disease caused by the varicella zoster virus (VZV) VZV –Herpesvirus (DNA) –Primary infection  chickenpox –Recurrent infection  herpes zoster (shingles)

Varicella Highly contagious and occurs worldwide Transmission: respiratory and contact Replication in nasopharynx and regional lymph nodes Incubation period is days (range days)

Varicella Complications Pre-Vaccine Era Hospitalization: 11,000 hospitalizations annually ( )* Death: 0.40 per 1,000,000 pop. ( )** *Galil K, Brown C, Lin F, Seward J. Hospitalizations for varicella in the United States, 1988 to Pediatr Infec Dis J. 2002;21: **Meyer PA, Seward JF, Jumaan AO, Wharton M. Varicella mortality: trends before vaccine licensure in the United States, J Infect Dis 2000;182:

Clinical Complications Bacterial infection of skin lesions Pneumonia (viral or bacterial) Central nervous system manifestations –Aseptic meningitis –Encephalitis Reye syndrome Postherpetic neuralgia (complication of zoster) Congenital Varicella Syndrome

Varicella Vaccine March 1995: varicella vaccine licensure July 1996: recommended by the Advisory Committee on Immunization Practices (ACIP) –12 mos. <13 years  1 dose –13 years and older w/o history of immunity  2 doses In 2004, varicella cases had decreased by 85% since 1995* Increasing proportion of cases are a result of breakthrough infection In June 2006, the ACIP recommended a routine second dose of varicella vaccine at 4-6 years of age * Centers for Disease Control and Prevention website, Varicella Active Surveillance Project

National Immunization Survey Estimated Varicella Vaccine Coverage Among Children Months of Age in NYC,

Data Sources New York State Hospital Discharge Data –Statewide Planning and Research Cooperative System (SPARCS) –Run by the New York State Department of Health –State law requires reporting of hospitalizations –Annual data sets –This evaluation focuses on NYC hospitalizations only –Diagnoses are ICD-9 coded, with a principle diagnosis and up to 14 additional diagnostic codes

Additional Data Sources NYC DOHMH Office of Vital Statistics –Death Certificates United States Census Bureau –Population estimates

Methods Varicella related hospitalization –Principle diagnosis –Other diagnosis Herpes zoster specific codes were excluded from the analysis Immune compromised was defined as having an ICD-9 code corresponding to the following conditions –HIV/AIDS, Leukemia, malignancies, blood dyscrasia, and childhood immunodeficiencies

Hospitalizations Varicella Diagnosis in NYC, Varicella Vaccine Licensure

Hospitalizations with Any Varicella Diagnosis by Age in NYC, Varicella Vaccine Licensure

Percent by Age of Hospitalizations with Any Varicella Diagnosis in NYC,

Hospitalizations with Any Varicella Diagnosis by Race/Ethnicity in NYC, Varicella Vaccine Licensure

Hospitalizations with Any Varicella Diagnosis by Race/Ethnicity in NYC, Varicella Vaccine Licensure

Hospitalizations with Any Varicella Diagnosis and an Immune Compromised Coded Condition* in NYC, Varicella Vaccine Licensure *HIV/AIDS, Leukemia, malignancies, blood dyscrasia, and childhood immunodeficiencies

Proportion of Varicella Hospitalizations with a Specific Immune Compromised Coded Condition in NYC, Varicella Vaccine Licensure

Deaths Due to Varicella as the Underlying or Contributing Cause in NYC, /1,000, /1,000, /1,000,000

Data Limitations Not necessarily hospitalized for varicella Not able to distinguish between primary varicella and disseminated zoster Substantial proportion (20%) of discharges are missing racial classification Race/Ethnicity data from SPARCS have not been validated

Conclusions Varicella hospitalizations have decreased significantly since the implementation of the varicella vaccine The majority of those now hospitalized for varicella are adults 20 years and older A racial disparity in varicella hospitalizations has decreased substantially

Conclusions (2) The proportion of those hospitalized for varicella who also have an immune compromised condition is increasing The rate of varicella hospitalizations among the immune compromised population is decreasing Deaths with varicella as both the underlying cause or contributing cause have decreased since implementation of the varicella vaccine

Acknowledgements NYC DOHMH –Bureau of Immunization Jane Zucker Christopher Zimmerman Vicky Papadouka –Division of Epidemiology Tejinder Singh Joseph Kennedy Tom Matte Kevin Konty Jennifer Norton Mary Huynh Wenhui Li Regina Zimmerman

ICD-9 Codes Varicella – Zoster – Immune Compromised –Leukemia: –Other Malignancy: –Childhood Immunodeficiency: ; –Other Blood Dyscrasia: –HIV: and Aidsflag variable (defined by SPARCS) Pregnancy – ; 647.6; 647.9;

Additional Results Average Length of Stay 7.3 Days5.8 Days Median Charge $5,947.16$13, Pregnancy Coded 2.64 per 100,000 population 0.54 per 100,000 population