Chickenpox
Display Page Index  + 
Varicella
chicken pox

Varicella is an acute disease caused by the varicella zoster virus (VZV). It is commonly known as chickenpox. Varicella is highly contagious. About 90% of susceptible persons in close contact with an infected person will develop varicella. The virus is spread mainly through infected respiratory secretions, but also can be spread through direct contact or inhalation of the watery fluids in the varicella skin lesions (vesicles).

About 12 days after exposure, a 1 to 2 day prodrome may begin. During the prodrome infected people, especially adults, develop fever and malaise. The prodrome is then followed by a rash. The varicella rash usually begins on the scalp and then moves downward and outward. It covers the trunk and extremities, with most lesions occurring on the trunk. The itchy rash progresses rapidly from macules to papules to vesicles, which then crust over. Infected people usually have 250 to 500 lesions, but can have as few as 10 or more than 1,500. The lesions can occur on the mucous membranes of the mouth and throat, respiratory tract, and the eye, as well as on the skin. The lesions are normally 1 to 4 mm in diameter and occur in successive crops over several days, so all stages of lesions may be present at any given time.

In general, varicella is usually mild and goes away without treatment. The most common complications include secondary bacterial infections of the skin, dehydration, pneumonia, and central nervous system manifestations. Adults, people who are immune compromised, and infants are most likely to experience complications from varicella infection.

Varicella can be prevented or the severity reduced if varicella vaccine is given within 3 to 5 days of exposure. In addition, varicella zoster immune globulin (VariZIG) can help reduce severity if given within 10 days of exposure. VariZIG is mainly used in persons at high risk for complications. Once symptoms develop, varicella illness cannot be prevented. However, several antiviral drugs, such as acyclovir, can reduce length and severity of illness if given within 24 hours of onset of the rash.

About the Vaccine

There is one varicella vaccine licensed for use in the United States. There is also a combination vaccine that contains varicella vaccine and MMR vaccine.

Varicella Vaccine Licensed for Use in the U.S.

Product: Varivax® (Varicella)
Manufacturer: Merck & Co
Year licensed: 1995
Product Insert

Combination Vaccines Containing Varicella Vaccine Licensed for Use in the U.S.

Product: ProQuad® (Measles, Mumps, Rubella, and Varicella)
Manufacturer: Merck & Co
Year licensed: 2005
Product Insert

Indications Contraindications and precautions
  • All infants and children 12 months of age and older.
  • Susceptible adolescents without documented evidence of immunity.
  • Susceptible adults without documented evidence of immunity.
  • People who have had a severe allergic reaction to a previous dose of varicella vaccine or a varicella vaccine component.* If you are administering varicella combined with MMR vaccine, also check for a history of severe allergic reaction to a previous dose of MMR vaccine.
  • People who are moderately or severely ill should wait until recovery before receiving any vaccine. Minor illnesses, such as a cold, are not a contraindication.
  • People who are pregnant or who have a possibility of pregnancy within 4 weeks.
  • People who are immune compromised due to disease, treatment, or medication.
  • People who have recently received blood products or immune globulin.
  • Unless the parent or caregiver expresses a preference for MMRV vaccine, separate MMR and varicella vaccines should be administered for the first dose for children 12 through 47 months of age.
  • A personal or family history of seizures is a precaution to MMRV vaccination.

* Varicella vaccine contains gelatin and neomycin (see package insert).

Vaccine Ages Dose/Route Routine Administration Schedule
Varivax 12 months to 13 years of age Dose: 0.5 mL

Route: Subcutaneously (SC)
2 doses at 12-15 months and 4-6 years of age. Minimum interval between doses is 3 months.
13 years of age and older 2 doses at least 28 days apart.
ProQuad (MMRV) 12 months through 12 years of age Dose: 0.5 mL

Route: Subcutaneously (SC)
2 doses at 12-15 months and 4-6 years of age. Minimum interval between doses is 3 months.
Unless the parent or caregiver expresses a preference for MMRV vaccine, separate MMR and varicella vaccines should be administered for the first dose for children 12 through 47 months of age.     
Varicella Vaccine Side Effects*
  • Soreness and swelling where the shot was given (about 1 out of 5 children and up to 1 out of 3 adolescents and adults).
  • Fever (1 person out of 10, or fewer).
  • Mild rash, up to a month after vaccination (about 1 person out of 25).
  • Seizure caused by fever (rare).
  • Pneumonia (very rare).
  • Severe allergic reaction (very rare).

Notes:
* When varicella antigen is given in combination with other antigens (e.g., MMR) in one vaccine, the other antigens in the vaccine may cause other side effects. For more information about these possible side effects, go to the MMR pages on the Vaccines section of this website. Note: The first dose of MMRV vaccine has been associated with rash and higher rates of fever than MMR and varicella given separately. Seizures caused by fever are also reported more often after MMRV.

Product Name Supplied Storage and Handling
Varivax - refrigerator stable formulation
Merck & Co
0.5 mL single dose vials with diluent (10 sets per package). Store refrigerated between 2° to 8°C (35° to 46°F) and protect from light. The vaccine may also be stored in a freezer; if subsequently transferred to a refrigerator, THE VACCINE SHOULD NOT BE REFROZEN. The diluent may be stored in the refrigerator with the lyophilized vaccine or separately at room temperature.

Varivax is a clear, colorless to pale yellow liquid after reconstitution. Discard reconstituted vaccine if not used within 30 minutes.
Varivax - freezer formulation
Merck & Co
0.5 mL single dose vials with diluent (10 sets per package). Store in the freezer between (-50°C and -15°C (58°F and +5°F) until it is reconstituted. Protect from light. VARIVAX may be stored at refrigerator temperature (36°F to 46°F, 2°C to 8°C) for up to 72 continuous hours prior to reconstitution. Vaccine stored at 2°C to 8°C which is not used within 72 hours of removal from +5°F (-15°) storage should be discarded. The diluent should be stored in the refrigerator or at room temperature.

Varivax is a clear, colorless to pale yellow liquid after reconstitution. Discard reconstituted vaccine if not used within 30 minutes.
ProQuad
Merck & Co
0.5 mL single dose vials with diluent (10 sets per package). Store in freezer between 50°C and -15°C (58°F and +5°F) until it is reconstituted. Protect from light. ProQuad may be stored at refrigerator temperature (36° to 46°F, 2° to 8°C) for up to 72 hours prior to reconstitution. Discard any ProQuad vaccine stored at 36° to 46°F which is not used within 72 hours of removal from 5°F (-15°C) storage. The diluent may be stored in the refrigerator with the lyophilized vaccine or separately at room temperature.

ProQuad is a clear, pale yellow to light pink liquid after reconstitution. Discard reconstituted vaccine if not used within 30 minutes.
11 Oct 05

Sample Q&A: The Vaccine

Will I ever need any additional doses of chickenpox (varicella) vaccine?
Booster doses are not currently recommended. But scientists are conducting studies to see if a dose of chickenpox (varicella) vaccine later in life might prevent reactivation of varicella virus, the disease known as zoster or “shingles.”
Supplemental Varicella Recommendations
Recommendations of the Advisory Committee on Immunization Practices
Recommendations of the Advisory Committee on Immunization Practices (ACIP)
Recommendations of the Armed Forces Epidemiological Board (AFEB)
Varivax (Merck) 01 Mar 14
Package Insert - Vaccine
Package Insert - Vaccine
New shipping package for VARIVAX from Merck Vaccines (replacing the use of dry ice with 6 refrigerant packs)
New shipping package for ZOSTAVAX from Merck Vaccines (replacing the use of dry ice with 6 refrigerant packs)
Vaccine Information Statement (Interim)
Vaccine Information Statement (Interim)