There is currently no inactive varicella vaccine available. The varicella vaccines that are currently available are live attenuated vaccines, which contain a weakened form of the varicella-zoster virus (VZV) that stimulates the immune system to develop immunity without causing the disease in normal individuals. The two main live attenuated varicella vaccines are the monovalent varicella vaccine and the combination measles, mumps, rubella, and varicella (MMRV) vaccine
Varicella vaccines and their efficacy
- Monovalent varicella vaccine (Varivax): This vaccine is licensed for use in the United States and has been shown to be effective in preventing varicella disease . A refrigerator-stable formulation of Varivax has been developed and has shown similar safety, tolerability, and immunogenicity profile to the frozen formulation
- Measles-mumps-rubella-varicella vaccine (MMRV): This quadrivalent vaccine is also licensed for use in the United States. It has been estimated that after vaccination at 12 through 23 months of age, 7 to 9 febrile seizures occur per 10,000 children who receive the MMRV
- Vaccine efficacy: The estimated vaccine efficacy over a 10-year observation period of 2 doses for prevention of any varicella disease is 98% (compared with 94% for 1 dose), with 100% efficacy for prevention of severe disease
Considerations for specific populations
- Immunocompromised individuals: Live attenuated vaccines are contraindicated in certain populations, such as immunocompromised individuals. For these individuals, varicella-zoster immune globulin (VZIG) may be considered for post-exposure prophylaxis. In the case of solid organ transplant recipients, the AST 2019 guidelines recommend administering varicella zoster immune globulin (VZIG) as soon as possible, and within 10 days of exposure, in seronegative patients exposed to VZV
- Solid organ transplant recipients (pre-transplant vaccination): The AST 2019 guidelines recommend offering vaccination with the live-attenuated varicella vaccine or the adjuvanted subunit vaccine, if not contraindicated, in caregivers, household members, and VZV-seronegative family members of solid organ transplant recipients, as a strategy to reduce VZV transmission
In conclusion, while there is currently no inactive varicella vaccine available, the live attenuated varicella vaccines have been shown to be effective in preventing varicella disease in normal individuals