Varicella-Zoster Vaccine Live
The Varicella-Zoster Virus Vaccine Live (Oka-Merck) Strain is a live attenuated vaccine designed to prevent chickenpox (varicella) caused by the varicella-zoster virus. It contains the Oka-Merck strain of the virus, which has been modified to stimulate immunity while minimizing the risk of wild-type disease. The vaccine is primarily used in children as a routine immunization and may also be given to susceptible adults.
Live attenuated vaccine for prevention of chickenpox using the Oka-Merck virus strain.
Key facts at a glance
- ATC
- J07BK01
- RxNorm
- 1292422
- Generic
- Varicella-Zoster Virus Vaccine Live (Oka-Merck) Strain
- Class
- atc-j07
- Brands
- Varivax, ProQuad
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- injection
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Dosage and administration
- Usual dose
- 500mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 250mg twice daily
- Maximum
- consult physician
- Frequency
- every 12 hours
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 400mg daily
- Maximum
- consult physician
- Frequency
- once daily
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
6 groupspregnancy
all trimestersavoid use
Live attenuated varicella vaccine should be avoided during pregnancy. Women should be advised to avoid pregnancy for at least 3 months after vaccination.
regular prenatal monitoring if accidentally exposed
Use of this medication in this population requires careful consideration of risks and benefits.
lactation
breastfeedingno adjustment needed
Generally considered compatible with breastfeeding. The live attenuated virus is not excreted in significant amounts in breast milk.
infant monitoring for signs of varicella infection
Use with caution and monitor for adverse effects.
pediatric_age
12 months to 12 yearsstandard pediatric dosing
Administer 0.5 mL subcutaneously at 12-15 months of age with a booster dose at 4-6 years. For catch-up vaccination, two doses at least 3 months apart are recommended.
standard post-vaccination observation for 15-20 minutes
geriatric
60 years and oldernot indicated for primary varicella prevention
The original varicella vaccine (Varivax) is not routinely indicated for adults over 60 for shingles prevention. For shingles prevention, use zoster vaccine (Zostavax or Shingrix) instead.
standard post-vaccination monitoring
Use with caution and monitor for adverse effects.
renal_impairment
moderate to severeno standard dosage adjustment
Use with caution in patients with severe renal impairment, especially if immunocompromised. Live vaccines are generally contraindicated in patients on immunosuppressive therapy for renal disease.
monitor for vaccine-related rash and signs of infection
Use with caution and monitor for adverse effects.
hepatic_impairment
moderate to severeno standard dosage adjustment
Use with caution in patients with moderate to severe hepatic impairment, particularly those with ascites or immunocompromise. Live vaccines generally contraindicated in advanced liver disease.
monitor for vaccine-related complications and liver function
Use with caution and monitor for adverse effects.
Statistics and clinical data
FDA Approval Year
Varivax (varicella vaccine) FDA approval year
Vaccine Type
Classification of the Oka-Merck strain vaccine type
Primary Indication
Main therapeutic use of Varivax and ProQuad vaccines
Vaccine Efficacy (2 doses)
Clinical efficacy of two-dose varicella vaccination regimen
Prevention of chickenpox (varicella) in children, adolescents, and adults who have not had varicella disease or been previously vaccinated. May also be considered for post-exposure prophylaxis in susceptible individuals.
The live attenuated Oka-Merck strain of varicella-zoster virus replicates in the body and stimulates the immune system to produce antibodies against the virus, providing active immunity against future varicella infection.
This is a live vaccine and is contraindicated in immunocompromised patients, pregnant women, and those with severe allergic reactions to any vaccine component. Should not be given with other live vaccines unless specified. Local injection site reactions and fever may occur after vaccination.
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
Consult healthcare provider for benefits vs risks assessment
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 24, 2026. · Read our editorial policy