From the Guidelines
I strongly recommend administering two 0.5-mL doses of single-antigen varicella vaccine live to adults without evidence of varicella immunity, given subcutaneously 4--8 weeks apart, as stated in the guidelines by the Advisory Committee on Immunization Practices (ACIP) 1. The varicella virus vaccine live is administered to adults who lack evidence of immunity to varicella, including those without documented evidence of varicella infection, previous vaccination, or laboratory evidence of immunity. Key points to consider when administering the vaccine include:
- The vaccine should be given subcutaneously in the outer aspect of the upper arm.
- The standard regimen consists of two 0.5-mL doses administered 4 to 8 weeks apart, with the option to administer the second dose without restarting the schedule if more than 8 weeks have elapsed since the first dose 1.
- Single-antigen varicella vaccine is the only licensed option for adults aged 13 years and older, as MMRV is not licensed for use in this age group 1.
- The vaccine is particularly important for certain groups, including healthcare workers, teachers, college students, military personnel, international travelers, and non-pregnant women of childbearing age.
- Contraindications to vaccination include pregnancy, immunocompromised status, and severe allergic reactions to vaccine components.
- Common side effects of the vaccine include soreness at the injection site, fever, and mild rash, and recipients should avoid close contact with immunocompromised individuals for 6 weeks following vaccination due to the small risk of virus transmission.
From the Research
Administration of Varicella Virus Vaccine Live in Adults
- The live varicella vaccine has been recommended for use in immunocompromised subjects and in adults who are susceptible to chickenpox 2.
- Live attenuated varicella vaccine was administered to healthy varicella-susceptible adults, with seroconversion to varicella-zoster virus (VZV) occurring in 82% after one dose and in 94% after two doses 3.
- Adults received two doses of 2500 pfu of lyophilized live-attenuated varicella vaccine, with antibody titers to whole VZV and to glycoprotein I (gpI) being significantly higher than those of children after one year 4.
Efficacy and Safety
- The vaccine offered significant protection against severe chickenpox in healthy adults, with protection after household exposure observed in 56% of subjects 3.
- Adverse effects were unusual, with one subject developing mild zoster caused by wild-type virus and 12 adults developing a mild breakthrough case of chickenpox after exposure to VZV 3.
- The severity of varicella was calculated using the modified Vázquez scale, with the vaccine efficacy against moderate or severe varicella being 99.0% for two doses of MMRV vaccine 5.
Immune Responses
- Humoral and cellular immune responses to whole varicella-zoster virus (VZV) antigen and the VZV proteins glycoprotein I (gpI) and nonglycosylated protein p170 were evaluated in healthy children and adults given lyophilized live-attenuated varicella vaccine 4.
- Antibody titers to whole VZV, gpI, and p170 were lower among both vaccine populations than titers in naturally immune individuals, but vaccinees who seroconverted initially retained detectable VZV antibodies 4.
- The vaccine dose affects vaccine-induced immunity to VZV, with higher antibody titers and cellular immunity observed in adults who received two doses of 2500 pfu compared to children who received one dose of 950 pfu 4.