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What is chickenpox vaccine?

Updated July 30, 2023


There are two live virus vaccines for chickenpox licensed for use in the U.S. by the FDA: Varivax,  a live varicella (chickenpox) virus vaccine manufactured by Merck; and ProQuad (MMRV),  a live virus vaccine containing measles, mumps, rubella and varicella (chickenpox), also manufactured by Merck. There is a higher risk of seizure following MMRV vaccination if this vaccine is administered as the first dose, when compared to the administration of separate doses of MMRII and varicella vaccines.  Links to the package inserts for each chickenpox vaccine can be found on the Chickenpox Quick Facts page.

Varivax  is a live, attenuated vaccine that contains the Oka/Merck strain of varicella (chickenpox) virus. This virus was taken from a child with wild-type chickenpox, inserted into human embryonic lung cell cultures, adapted to and grown in embryonic guinea pig cell cultures and then propagated in human diploid cell cultures (WI-38- a human diploid cell line derived from the lung tissue of a three-month human female embryo).  Further passage of the chickenpox virus for vaccine usage was performed in human diploid cell cultures (MRC-5 cells- a human cell line developed in 1966 from lung tissue taken from a 14 week old male aborted fetus)  that Merck has declared to be free of adventitious agents.

Varivax is a lyophilized preparation containing glutamate, sucrose, phosphate, and processed gelatin as stabilizers. When reconstituted as directed and stored at room temperature for a maximum of 30 minutes, each approximately 0.5mL dose of Varivax contains a minimum of 1,350 plaque-forming units (PFU) of Oka/Merck varicella virus. Each 0.5-mL dose contains hydrolyzed gelatin, monosodium L-glutamate (MSG), sodium chloride, sucrose, sodium phosphate dibasic, potassium phosphate monobasic, and potassium chloride. Varivax also contains residual components of MRC-5 cells, including DNA, protein, and trace quantities of sodium phosphate monobasic, neomycin, EDTA, and fetal bovine serum. The vaccine is approved to be administered both subcutaneously and intramuscularly, to be given immediately after reconstitution. 

ProQuad  vaccine is licensed and recommended for use in children aged 12 months to 12 years of age. ProQuad (MMRV) is a combined, attenuated, live virus vaccine containing measles, mumps, rubella, and varicella viruses.  ProQuad is a sterile lyophilized preparation of the components of M-M-R II (Measles, Mumps, and Rubella Virus Vaccine Live), and varicella virus vaccine live, the Oka/Merck strain of varicella-zoster virus propagated in MRC-5 cells. 

The growth medium for measles and mumps found in ProQuad  is a buffered salt solution containing vitamins and amino acids and it is supplemented with fetal bovine serum containing sucrose, phosphate, glutamate, recombinant human albumin, and neomycin. The growth medium for rubella is a buffered salt solution containing vitamins and amino acids and supplemented with fetal bovine serum containing recombinant human albumin and neomycin. Sorbitol and hydrolyzed gelatin stabilizer are added to the individual virus harvests. The Oka/Merck strain of the live attenuated varicella virus, initially obtained from a child with wild-type varicella, introduced into human embryonic lung cell cultures, adapted to and propagated in embryonic guinea pig cell cultures and finally propagated in human diploid cell cultures (WI-38), is then added to the measles, mumps, and rubella vaccine. This vaccine is approved to be given by either subcutaneous or intramuscular injection.

According to Merck, ProQuad vaccine is screened for adventitious agents. Each dose of ProQuad contains sucrose, hydrolyzed gelatin, sorbitol, MSG, sodium phosphate, human albumin, sodium bicarbonate, potassium phosphate and chloride, neomycin, bovine calf serum, chick embryo cell culture, WI-38 human diploid lung fibroblasts and MRC-5 cells.    ProQuad also contains a higher amount of Oka/Merck strain varicella plaque forming units (PFU) than Varivax, the single antigen varicella vaccine. 

The ProQuad vaccine package insert states that one month should lapse between administration of ProQuad and another measles-containing vaccine such as MMRII and at least three months should lapse between ProQuad and any varicella containing vaccine. 

The CDC recommends children receive a first dose of chickenpox vaccine between 12 and 15 months and a second dose between 4 and 6 years. The CDC also recommends two doses of chickenpox vaccine be administered 4 to 8 weeks apart to all school-aged students, post-secondary aged students, and all healthy adults who lack immunity to chickenpox. 

IMPORTANT NOTE: NVIC encourages you to become fully informed about Chickenpox and the Chickenpox vaccine by reading all sections in the Table of Contents , which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself or your child. This information is for educational purposes only and is not intended as medical advice.

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