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Diseases

What is Chickenpox?Updated 4-3-24
  • Chickenpox, or Varicella, is a very contagious respiratory virus caused by the varicella-zoster virus (VZV).
  • Chickenpox causes itchy rashes with fluid-filled blisters that later turn into scabs throughout the body. It can also cause serious disease, especially in pregnant persons, young babies, and people with weakened immune response. People with chickenpox can develop shingles later in life.
  • The best way to prevent chickenpox is to get the chickenpox vaccine.
Chickenpox Image

Fact Sheet

English | translations pending
Chickenpox: Symptoms and Complications

Chickenpox usually begins with:

  • Fever
  • Tiredness
  • Headache
  • Loss of appetite

After these initial symptoms, an itchy rash with fluid-filled blisters appears throughout the body. Chickenpox blisters typically start at the chest, back, and face before spreading over the entire body. Blisters turn into scabs in 4-7 days, after other signs of illness.

Chickenpox can cause several health complications. Complications include Group A streptococcal disease (skin and soft tissue infections), encephalitis (swelling of the brain) pneumonia (lung infection), bleeding problems, sepsis (bloodstream infection) and dehydration.

Those who are more likely to have serious complications due to chickenpox are:

  • Infants
  • Adolescents
  • Adults
  • Pregnant People
  • People with weakened immune systems

If you think you may have these symptoms, talk with your healthcare provider.

How does Chickenpox Spread?
  • Chickenpox mainly spreads through close contact with an infected person.
  • The virus spreads easily through the air when an infected person breathes, talks, coughs, or sneezes.
  • A person infected with chickenpox can spread the disease before they have any symptoms.
    • This could be up to 2 days before the chickenpox rash appears and up to 7 days after the rash appears.
    • It takes about 10 to 21 days after exposure with an infected person for someone to develop chickenpox.

If you think you or your someone in your family may have chickenpox and have not been vaccinated against chickenpox: Stay home and call your doctor and let them know of your concerns.

  • Stay away from other individuals or large groups in places such as school, daycare, and waiting rooms, before speaking to your doctor.

If you think you have been exposed to chickenpox:

  • Call your doctor immediately to let them know you have may have been exposed to someone with chickenpox.
  • Your doctor may be able to determine if you have protection against chickenpox based on your vaccine record or previous lab results.
  • Your doctor may also make special arrangements to evaluate you to limit risk to other patients and staff.
  • Make sure to wear a facemask that covers your nose and mouth.
  • Stay away from places where there are large groups of people who are at higher risk of getting sick, such as schools, hospitals, or childcare. Do not return until your doctor says it is okay to return. This will help make sure that you do not spread chickenpox to others.
Information for the Public
Vaccine Information
  • The best way to prevent chickenpox is to get the chickenpox vaccine. Everyone — including children, adolescents, and adults — should get two doses of chickenpox vaccine if they have never had chickenpox or were never vaccinated.
  • The chickenpox vaccine is safe and works very well in preventing chickenpox. Two-doses of the vaccine is 92% effective and one-dose is 82% effective at preventing chickenpox. If a vaccinated person does get chickenpox, the symptoms are usually milder with fewer or no blisters, and low or no fever.
Vaccine Recommendations

Who SHOULD get the vaccine:

  • There are two chickenpox vaccines licensed in the United States — VZV (varicella zoster virus) and MMRV (measles, mumps, rubella, and varicella).
  • Most individuals born or attending school in the United States get vaccinated when they are children. They receive their first dose at 12-15 months of age and the second dose at 4-6 years of age.
  • Children 12 months through 12 years may receive either MMRV or VZV vaccine.
  • People 13 years of age and older who have never had chickenpox vaccine should receive 2 doses of VZV vaccine.

Chickenpox vaccine is not recommended for persons who have:

  • A severe, life-threatening allergy or allergic reaction to MMRV or VZV vaccine or vaccine components
  • Certain illnesses affecting the bone marrow
  • A moderate or severe concurrent illness
  • A severely weakened immune system
  • A current pregnancy or may become pregnant
Where to get the Vaccine

There are many places to get the chickenpox vaccine. If you have insurance, talk to your doctor or check with your local pharmacy to see what vaccines are offered. Most health insurances cover the cost of all recommended vaccines for children and adults.

If you are uninsured or underinsured, there are programs available to help cover the cost of vaccines. Children who are 18 years of age or younger are eligible to receive vaccines at no cost through the Vaccines for Children (VFC) Program if they are:

  • Eligible for or are enrolled in Medi-Cal
  • American Indian or Alaskan Native
  • Uninsured (do not have health insurance)
  • Underinsured (private health insurance does not cover the full cost of vaccines)

Click to see if your child is eligible to receive VFC vaccines: English | Spanish

Uninsured or underinsured adults can access free or low cost vaccines at select clinics enrolled in the Vaccines for Adults (VFA) program. For more information on who is eligible, read VFA Eligibility Based on Insurance Status. You can use the following resources for more information on locating clinics:

You can also dial 2-1-1 for a list of free or low cost vaccine clinics. This includes Vaccines for Children (VFC) provider locations that serve Medi-Cal eligible children and uninsured or underinsured adults. Learn more about specific vaccine information for different age groups:

Keeping Record of Your Immunization Records

Are you not sure if you have been vaccinated against chickenpox or you can’t find your vaccine records?

If you need official copies of your vaccine records, or if you need to update your personal records:

Information for Providers
Clinical Presentation
  • Chickenpox is characterized by a generalized, pruritic rash which progresses rapidly from macular to papular to vesicular lesions before crusting. Lesions develop in crops, and therefore, lesions in all stages of development can be present at the same time. Rash typically appears on the chest, back and face, and then spreads to the rest of the body.
  • Chickenpox rash in vaccinated patients can appear as maculopapular rather than vesicular. This presentation is becoming increasingly common with the introduction of childhood vaccinations for varicella.
  • The incubation period for chickenpox can range from 10 to 21 days. A prodrome of fever and malaise can occur 1 to 2 days before rash onset, especially in adults. Symptoms can appear mild in otherwise healthy children, but certain individuals are at higher risk for complications including infants, adolescents, adults, pregnant persons and immunocompromised individuals.
  • Chickenpox is transmitted through droplets or airborne spread of vesicle fluid or by secretions of the respiratory tract. Scabbed lesions are not infectious. A person with chickenpox is considered contagious 1 to 2 days before rash onset until all lesions have crusted.
Isolation of Suspected Cases
  • Patients with signs or symptoms of varicella should be isolated from other patients prior to or as soon as possible after entry into the facility.
  • Patients with suspected chickenpox should wear a well-fitted medical mask or respirator and be placed in an airborne infection isolation room if one is available. If this cannot take place, escort masked patient away from other patients directly to a private room for evaluation and specimen collection.

Regardless of prior immunity status, all healthcare staff entering the same room as the patient should use respiratory protection consistent with airborne infection control precautions.

Reporting
  • Report the following cases of chickenpox:
    • Hospitalized cases
    • Deaths
    • An outbreak of 3 or more cases with close contact (direct physical or face-to-face contact, or 1 or more hours in the same room) within an incubation period of 21 days
    • 1 case in a high-risk setting (ex. healthcare facility, juvenile hall, prison or jail, residential facility, homeless shelter)
  • Contact Public Health within 1 working day
Diagnostic Testing
  • Laboratory confirmation is important for suspected chickenpox cases. Healthcare providers should obtain a swab of vesicular fluid for PCR testing or in the absence vesicular lesions, scrapings of maculopapular lesions.
  • Testing of IgM serology is not recommended but can indicate an acute varicella infection along with chickenpox symptoms.
Vaccine Recommendations
Varicella
Vaccines
Number of
Doses
Age Recommended
Age
Dose and
Route
1st Dose 2nd Dose
Varivax ®
(Merck)
2 12-15 Months 4-6 Years
At least 3 months after the 1st dose
12 months 0.5mL Intramuscular (IM)
or
Subcutaneous (SQ)
13+ Years At least 4 weeks after the 1st dose
ProQuad ® 1
(Merck)
Measles, Mumps, Rubella & Varicella
2 12-47 Months 4-6 Years
Or at least 3 months after the 1st dose
12 months to 12 years SQ

1 Associated with a higher risk for fever and febrile seizures in children 12-23 months of age.

Post Exposure Prophylaxis
  • Individuals who do not have evidence of immunity should be vaccinated with varicella – containing vaccine within 3-5 days of exposure to chickenpox.
  • Certain high-risk groups, including immunocompromised children, pregnant women, and infants can be offered varicella-zoster immune globulin (VariZIG) within 10 days of exposure to prevent chickenpox from developing or lessen its severity.
Treatment
  • Oral acyclovir or valacyclovir is recommended as a treatment to certain groups, including:
    • Healthy people over 12 years old
    • People with chronic cutaneous or pulmonary disorders
    • People receiving long-term salicylate therapy
    • People receiving short, intermittent or aerosolized courses of corticosteroids
    • Secondary cases within a household
  • Oral acyclovir or valacyclovir should be given within the first 24 hours after a rash starts.
  • Treatment is not recommended for otherwise healthy children who are experiencing varicella without complications.


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  • Public Health has made reasonable efforts to provide accurate translation. However, no computerized translation is perfect and is not intended to replace traditional translation methods. If questions arise concerning the accuracy of the information, please refer to the English edition of the website, which is the official version.

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