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Indiana State Department of Health

ISDH Home > About the Agency > Schools Communicable Disease Guide > Varicella (Chickenpox) Varicella (Chickenpox)

Clinical Description
Varicella is a viral illness that is very contagious and is caused by the herpes zoster virus.  Early symptoms can include fever and fatigue which begin about 10-21 days after exposure.  These symptoms are followed by the appearance of flat, red spots which progresses into an itchy, rash with fluid-filled vesicles that is characteristic of the disease.  Lesions appear in crops over several days and lesions will be present in several stages of development. As varicella vaccine coverage increases, most cases are now break-through cases, which are often less severe with less than 50 lesions and do not progress to the vesicular stage.  Varicella can cause serious complications including pneumonia, encephalitis, secondary bacterial infections, and even death.

Incubation Period
The incubation period normally ranges from 10-21 days, but most is commonly 14-16 days.

Mode of Transmission
Transmission occurs primarily through contact with infectious respiratory secretions and airborne droplets. Direct contact with open vesicles can also transmit infection.

Period of Communicability
A person can spread the herpes zoster virus 2-5 days before the onset of the rash until all of the lesions have crusted over or faded, typically 7 days.

Infected persons are excluded from schools and day care centers, public gatherings, and contact with susceptible persons until vesicles become dry or in cases of mild, “break-through” disease until the lesions have faded or disappeared. For more information, please see the Communicable Disease Reporting Rule 410 IAC 1-2.3 sec 110


• Vaccinate with a single dose of live, attenuated varicella vaccine at 12-15 months of age and revaccinate with a second dose at 4-6 years of age. School immunization requirements for varicella can be found at:
• Review immunization records to identify susceptible individuals or those who have received only one dose of varicella vaccine.
• Varicella vaccine can be administered within 3-5 days of an exposure to prevent or modify the severity of disease.
• School personnel planning a pregnancy should be immunized 3 months prior to pregnancy.
• Promptly report all suspected individual cases and outbreaks to the local health department. Laboratory testing is recommended during outbreak situations.

Other Resources

Indiana State Department of Health Quick Fact Link:

Centers for Disease Control and Prevention (CDC) Links: