Varicella Vaccine (Varivax) Composition
Varivax contains a minimum of 1,350 plaque-forming units (PFUs) of the live-attenuated Oka/Merck strain of varicella-zoster virus per 0.5 mL dose, along with 12.5 mg of hydrolyzed gelatin, trace amounts of neomycin and fetal bovine serum, 25 mg of sucrose, and trace residual components of MRC-5 cells (including DNA and protein). 1
Active Ingredient
- Live-attenuated Oka/Merck strain of varicella-zoster virus: Minimum of 1,350 PFUs (approximately 3.13 log10 PFUs) per 0.5 mL dose 1
- The Oka strain was originally isolated in Japan in the early 1970s from vesicular fluid of a healthy child with natural varicella 1
- The virus was attenuated through sequential propagation in cultures of human embryonic lung cells, embryonic guinea-pig cells, and human diploid cells (WI-38) 1
- The Oka/Merck vaccine underwent further passage through human diploid-cell cultures (MRC-5) for a total of 31 passages 1
Inactive Ingredients and Excipients
- Hydrolyzed gelatin: 12.5 mg per dose 1
- Sucrose: 25 mg per dose 1
- Neomycin: Trace amounts 1
- Fetal bovine serum: Trace amounts 1
- Residual MRC-5 cell components: Trace amounts, including DNA and protein 1
Important Product Characteristics
- No preservatives: The vaccine does not contain thimerosal or other preservatives 1
- No egg protein: The vaccine contains no egg protein, making egg allergy not a contraindication 2
- Lyophilized formulation: The vaccine is freeze-dried and must be stored frozen at an average temperature of -15°C or colder until reconstitution 1
- Post-reconstitution stability: After reconstitution as directed in the package insert, the vaccine should be kept at room temperature for a maximum of 30 minutes 1
Clinical Relevance of Components
- Neomycin content: History of severe anaphylactic reaction to neomycin is a contraindication to vaccination 2
- Gelatin content: History of severe anaphylactic reaction to gelatin is a contraindication to vaccination 2
- MRC-5 cell components: These are residual components from the cell culture manufacturing process and are present only in trace amounts 1