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Varicella (chicken pox) vaccine (oka strain)


Powder and solvent to produce a solution for injection of live attenuated varicella zoster (Oka strain) virus propagated in MRC5 human diploid cells and containing 10 to the power of 3.3 plaque forming units per 0.5ml dose.

Drugs List

  • varicella zoster (oka strain) live vaccine
  • VARILRIX live vaccine
  • Therapeutic Indications


    For active immunisation against varicella of healthy subjects (from 9 months of age). It is recommended to vaccinate susceptible, healthy, close contacts of subjects at risk of severe varicella, in order to reduce the risk of transmission of wild-type virus to these patients.
    For comprehensive information or advice on this product or the immunisation programme in the UK, the following website should be accessed.



    Two doses each of 0.5ml of reconstituted vaccine should be given with an interval between doses of at least 6 weeks, but no less than 4 weeks.


    There are no data on immune responses to varicella vaccine in the elderly.


    Children aged 1 to 18 years
    Two doses each of 0.5ml of reconstituted vaccine should be given with an interval between doses of at least 6 weeks, but no less than 4 weeks.

    Children aged 9 months to 1 year
    Two doses each of 0.5ml of reconstituted vaccine should be given with a minimum interval between doses of at least 3 months.

    Children aged under 9 months

    Additional Dosage Information

    There are insufficient data on the long term protective efficacy of the vaccine, but there is no evidence that further doses are routinely required following completion of a two-dose regimen in healthy adolescents and adults.

    If the vaccine is to be administered to seronegative subjects before a period of planned or possible immunosuppression (such as those awaiting organ transplants and those in remission from malignant disease), the timing of the vaccinations should take into account the delay after the second dose before maximal protection might be expected (about 6 weeks).

    One dose of this varicella-containing vaccine may be administered following the first dose of a different varicella-containing vaccine.


    For subcutaneous administration only. The deltoid region or the anterolateral area of the thigh is the preferred site of injection.

    If it is considered necessary to administer another live vaccine at the same time, the vaccines must be given as separate injections and at different body sites.


    Alcohol and other disinfecting agents must be allowed to evaporate from the skin before injection of the vaccine since they may inactivate the virus.

    Any unused product or waste material should be disposed of in accordance with local requirements.


    Reconstitute with the water for injections from the vial solvent supplied with the product. After addition of the diluent, the mixture should be well shaken until the lyophilised pellet is completely dissolved in the diluent.

    The colour of the reconstituted vaccine may vary from peach to pink due to minor variations in pH. Examine the diluent and the reconstituted vaccine visually for foreign particulate matter and/or variation in physical appearance before administration. In the event of either being observed, discard the diluent or the reconstituted vaccine.

    The vaccine should be used immediately. If not used immediately, in-use storage times and conditions prior to use are the responsibility of the user and would not normally be longer than 8 hours at 2-8 degrees C, unless reconstitution has taken place in controlled and validated aseptic conditions.


    Do not mix with any other medicinal product in the same syringe.


    Children under 9 months of age.

    Pregnancy - see Pregnancy section

    Primary or acquired immunodeficiency states with a total lymphocyte count less than 1,200 per mm cubed or presenting other evidence of lack of cellular immune competence, such as subjects with leukaemias, lymphomas, blood dyscrasias, clinically manifest HIV infection or receiving immunosuppressive therapy (including high dose corticosteroids).

    Subjects who have received immune globulins or blood transfusion within the last 3 months should not be vaccinated because of the likelihood of vaccine failure from passively acquired antibody to the varicella virus.

    Acute, severe febrile illness (postpone vaccination until recovery). However, the presence of a minor infection is not a contraindication.

    In patients with phenylketonuria (PKU). Phenylalanine may be harmful for individuals with PKU.

    Precautions and Warnings

    Appropriate medical treatment and supervision should always be available in case of an anaphylactic reaction following administration of the vaccine.

    Postpone immunisation if there is active or suspected infection.

    Women of child bearing age must be advised to take adequate contraceptive precautions to prevent pregnancy occurring between the two doses and for 3 months after the second dose.

    Serological studies indicate that the vaccine does not completely protect all individuals from naturally-acquired varicella and cannot be expected to provide maximal protection against infection with varicella zoster virus until about 6 weeks after the second dose.

    Administration of the vaccine to subjects who are in the incubation period of varicella zoster infection cannot be expected to protect against clinically manifest disease or to modify the course of the disease.

    The rash produced during naturally-acquired primary varicella zoster infection may be more severe in those with existing severe skin damage, including severe eczematous conditions. It is not known if there is an increased risk of vaccine-associated skin lesions in such subjects, but the possibility should be taken into consideration before vaccination.

    Avoid salicylates (including aspirin) during the period between the two doses of vaccine and for 6 weeks afterwards as Reye's syndrome has been reported following the use of salicylates during natural varicella infection.

    Transmission of vaccine virus
    Transmission of the vaccine viral strain has been shown to occur from healthy vaccinees to healthy contacts, pregnant contacts and immunosuppressed contacts. Such transmission is rare and has not been confirmed to occur in the absence of vaccine-associated cutaneous lesions in the vaccinee.
    In healthy contacts of vaccinees, seroconversion has sometimes occurred in the absence of any clinical manifestations of infection. Clinically apparent infections due to transmission of the vaccine have been associated with few skin lesions and minimal systemic upset.

    If the vaccinee develops a cutaneous rash thought likely to be vaccine related (especially vesicular or papulovesicular) within 4 to 6 weeks of the first or second dose, contact with the following groups must be avoided until this rash has completely disappeared:
    varicella-susceptible pregnant women
    individuals at high risk of severe varicella, such as those with primary and acquired immunodeficiency states (including those with leukaemias, lymphomas, blood dyscrasias, clinically manifest HIV infection and patients receiving immunosuppressive therapy, including high dose corticosteroids).

    In the absence of a rash in the vaccinee, the risk of transmission of the vaccine viral strain to contacts in the above groups appears to be extremely small. Nevertheless, vaccinees (e.g. healthcare workers) who are very likely to come into contact with persons in the above groups should preferable avoid any such contact during the period between vaccinations and for 4 to 6 weeks after the second dose. If this is not feasible, then vaccinees should be vigilant regarding the reporting of any skin rash during this period, and should take steps as above if a rash is discovered.

    In healthy, seronegative children vaccinated as close contacts of persons at high risk of severe varicella infection continued contact between the vaccinee and the person at risk may be unavoidable. The risk of transmission of the attenuated viral strain from the vaccinee should be weighed against the potential for acquisition of wild-type varicella zoster by the at-risk person.

    The Oka vaccine viral strain has been shown to be sensitive to aciclovir.

    If a measles containing vaccine is not given at the same time as a varicella-containing vaccine, it is recommended that an interval of at least one month between vaccinations is respected, since it is recognised that measles vaccination may cause short-term suppression of the cell-mediated response.

    Syncope can occur following, or even before, any vaccination especially in adolescents as a psychogenic response to the needle injection. This can be accompanied by several neurological signs such as transient visual disturbance, paraesthesia and tonic-clonic limb movements. It is important that procedures are in place to avoid injury.

    Breastfeeding - see Lactation section

    This product contains phenylalanine.

    Pregnancy and Lactation


    The vaccine is contraindicated in pregnancy.

    Varicella zoster virus may cause severe clinical disease in pregnant individuals and may adversely affect the foetus and/or result in perinatal varicella, depending on the gestational stage when the infection occurs. As the possible effects of infection with the vaccine viral strain on the mother and the foetus are unknown, the vaccine must not be administered to pregnant women.

    Women of child-bearing potential must be advised to take adequate precautions to avoid pregnancy occurring between the two vaccine doses and for 3 months following the second dose.

    The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14-17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( ) or if this is unavailable at the backup site ( ).

    Licensed in pregnancy? - No, contraindicated


    This vaccine is not generally recommended for breastfeeding due to the theoretical risk of vaccine virus transmission to the infant.

    Studies have shown that the vaccine virus is not transferred to the infant through breast milk and therefore breastfeeding women can be vaccinated if indicated.

    Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
    Specialist advice is available from the UK Drugs in Lactation Advisory Service at

    Effects on Ability to Drive and Operate Machinery

    It would not be expected that vaccination would affect the ability to drive or operate machinery.


    Advise women of child-bearing age to take adequate contraceptive precautions between the two doses of vaccine and for three months after the second dose.

    Advise vaccinees that if they develop a rash they should avoid contact with varicella-susceptible pregnant women and individuals at high risk of severe varicella infection.

    Advise patients to avoid salicylates, including aspirin, during the period between the two doses of vaccine and for 6 weeks afterwards.

    Side Effects

    Swelling (injection site)
    Erythema at injection site
    Local pain (injection site)
    Abdominal pain
    Upper respiratory tract infection
    Facial oedema
    Herpes zoster
    Hypersensitivity reactions
    Anaphylactic reaction
    Decreased appetite
    Influenza-like symptoms


    It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.

    The following number will direct the caller to the relevant local centre (0844) 892 0111

    Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( ) or if this is unavailable at the backup site ( ).

    Shelf Life and Storage

    Store at 2 to 8 degrees C (in a refrigerator).

    Store in the original package in order to protect from light.

    The lyophilised vaccine is not affected by freezing.

    Further Information

    Last Full Review Date: July 2012

    Reference Sources

    Drugs During Pregnancy and Lactation: Treatment Options and Risk Assessment, 2nd edition (2007) ed. Schaefer, C., Peters, P. and Miller, R. Elsevier, London.

    Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk, 9th edition (2011) ed. Briggs, G., Freeman, R. and Yaffe, S. Lippincott Williams & Wilkins, Philadelphia.

    Summary of Product Characteristics: Varilrix 10 3.3 PFU/0.5ml, powder and solvent for solution for injection. GlaxoSmithKline UK. Revised October 2021.

    Immunisation against infectious disease (The Green Book), November 2006.
    Available at:
    Last accessed July 11, 2012.

    NICE Evidence Services Available at: Last accessed: 27 September 2017
    US National Library of Medicine. Toxicology Data Network. Drugs and Lactation Database (LactMed).
    Available at:
    Varicella Vaccine. Last revised: April 3, 2012.
    Last accessed: July 11, 2012.

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