12-Varicella7p

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Varicella andVaricella Vaccine

Epidemiology and Prevention of Vaccine-Preventable Diseases

National Immunization ProgramCenters for Disease Control and Prevention

Revised March 2002


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Varicella

Acute viral illness

Zoster described in premedieval times

Varicella not differentiated fromsmallpox until end of 19th century

Infectious nature demonstrated in 1875


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Varicella Zoster Virus

Herpes virus (DNA)

Primary infection results in varicella

(chickenpox)

Recurrent infection results in herpes

zoster (shingles)

Short survival in environment


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Varicella Pathogenesis

Respiratory transmission of virus

Replication in nasopharynx and

regional lymph nodes

Repeated episodes of viremia

Multiple tissues, including sensoryganglia, infected during viremia


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Varicella Clinical Features

Incubation period 14-16 days (range10-21 days)

Mild prodrome for 1-2 days

Generally appear first on head; most

concentrated on trunk

Successive crops (2-4 days) of pruritic

vesicles


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Herpes Zoster

Reactivation of varicella zostervirus

Associated with:

aging

immunosuppression intrauterine exposure

varicella at


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Varicella Complications

Bacterial infection of lesions

CNS manifestations

Pneumonia (rare in children)

Hospitalization ~3 per 1000 cases

Death ~ 1 per 60,000 cases


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Groups at Increased Risk ofComplications of Varicella

Normal adults

Immunocompromised persons

Newborns with maternal rash

onset within 5 days before to 48hours after delivery


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Congenital Varicella Syndrome

Results from maternal infection duringpregnancy

Period of risk may extend through first 20weeks of pregnancy

Atrophy of extremity with skin scarring,

low birth weight, eye and neurologicabnormalities

Risk appears to be small (


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Varicella Laboratory Diagnosis

Isolation of varicella virus fromclinical specimen

Significant rise in varicella IgG byany standard serologic assay (e.g.,enzyme immunoassay)

Positive serologic test for varicellaIgM antibody


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Varicella Epidemiology

Reservoir Human

Transmission Airborne dropletDirect contact with lesions

Temporal pattern Peak in winter and early

spring (U.S.)

Communicability 1-2 days before to 4-5days after onset of rash

May be longer inimmunocompromised


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60

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120


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3 sites conducting activesurveillance for varicella since 1995

Combined population 1.2 million

Combined birth cohort 21,000

2000 varicella vaccine coverage 74%-84%

Active Varicella Surveillance

Seward JF, et al. JAMA 2002;287:606-11


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100

200

300

400

500

Cases

Varicella Cases by Month - AntelopeValley CA, 1995 - 2001

1995 1996 1997 1998 1999 2000 2001


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Reduction of Reported VaricellaCases in 2000 Compared With 1995

AgeAntelopeValley, CA

WestPhila., PA

TravisCounty, TX

< 1 year 69% 68% 81%14 years 83% 83% 90%

59 years 63% 77% 77%

1014 years 66% 80% 75%

1519 years 85% 81% 83%

>20 years 66% 68% 64%

Overall 71% 79% 84%

Seward JF, et al. JAMA 2002;287:606-11

-------Surveillance Area-------


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Varicella Vaccine

Composition Live virus (Oka-Merck strain)

Efficacy 95% (Range, 65%-100%)

Duration of >7 yearsImmunity

Schedule 1 Dose (


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Breakthrough Infection

Immunity appears to be longlasting

1% of recipients of current lots per year

develop chickenpox

Breakthrough disease much milder than inunvaccinated persons

No evidence that risk of breakthroughinfection increases with time sincevaccination


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Retrospective cohort study of 115,000children vaccinated in 2 HMOs duringJanuary 1995 through December 1999

Risk of breakthrough varicella 2.5 timeshigher if varicella vaccine administered 30 days after MMR

MMWR 2001;50(47):1058-61

Breakthrough Infection


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Varicella Vaccine RecommendationsChildren

Routine vaccination at 12 to 18months of age

Recommended for all susceptiblechildren by the 13th birthday


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Varicella Vaccine RecommendationsAdolescents and Adults

Persons >13 years of age withouthistory of varicella

Two doses separated by 4 - 8 weeks

Up to 90% of adults immune

Serologic testing may be cost effective


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Susceptible persons at high riskof exposure or severe illness

Teachers of young children

Institutional settings

Military Women of childbearing age

International travelers


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Susceptible persons likely toexpose persons at high risk forsevere illness

Health care workers

Family members of immuno-compromised persons


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Vaccination of Health Care Workers

Recommended for allsusceptible health care workers

Prevaccination serologicscreening probably cost effective

Postvaccination testing notnecessary or recommended


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Varicella VaccinePost-exposure Prophylaxis

Varicella vaccine is recommendedfor use in susceptible person after

exposure to varicella70%-100% effective if given

within 72 hours of exposure

not effective if >5 days but willproduce immunity if not infected


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Varicella Vaccine Adverse Reactions

Injection site complaints - 20%

Rash - 3%-4%

May be maculopapular ratherthan vesicular

Average 5 lesions

Systemic reactions uncommon


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Zoster Following Vaccination

Most cases in children

Risk from wild virus 4 to 5 timeshigher than from vaccine virus

Mild illness without complications


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Varicella VaccineContraindications and Precautions

Severe allergy to prior dose or

vaccine component

Pregnancy

Immunosuppression

Moderate or severe acute illness

Recent blood product


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Varicella Vaccination

in Pregnancy Registry

800.986.8999


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Varicella VaccineUse in Immunocompromised Persons

Most immunocompromised personsshould not be vaccinated

Vaccinate persons with isolatedhumoral immunodeficiency

Consider varicella vaccination forasymptomatic HIV-infected children withCD4% >25% (CDC class A1 and N1)


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Transmission of VaricellaVaccine Virus

Transmission of vaccine virusuncommon

Asymptomatic seroconversionmay occur in susceptible contacts

Risk of transmission increased ifvaccinee develops rash


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Vaccine Storage and Handling

Store frozen at -15 C (+5 F) or lower

Generally should not be refrozen

Store diluent at room temperature orrefrigerate

Discard if not used within 30 minutesof reconstitution


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Varicella Vaccine

Information800-9VARIVAX


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Varicella Vaccine Coverage

National Immunization Surveyestimate of children 19-35months of age - 2000

75% nationwide

Variation by state (40%-85%)

Significant improvement since1996 (16%)


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Varicella Zoster Immune Globulin (VZIG)

May modify or prevent disease if given


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Varicella Antiviral Therapy

Not recommended for routine use amongotherwise healthy infants and childrenwith varicella

Consider for persons age >13 years

Consider for persons with chroniccutaneous or pulmonary disorders, long-term salicylate therapy, or steroid therapy

IV in immunocompromised children and

adults with viral-mediated complications Not recommended for post-exposure

prophylaxis

2000 AAP Red Book


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National Immunization Program

Hotline 800.232.2522

Email [email protected]

Website www.cdc.gov/nip

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