varicella vaccination in children

Last reviewed 02/2023

Varicella vaccine is a lyophilised preparation which contains live attenuated organisms of the Oka strain of varicella zoster virus (1)

• should be administered as deep subcutaneous injection and can be given together with other live vaccines such as MMR
• children from one year to under 13 years of age; a single dose of varicella vaccine will give protection for around 90% of children
• children aged 13 years or older and adults - should receive two doses of varicella vaccine, four to eight weeks apart, around 75% will have protection against clinical chickenpox (1)

A critical review has examined the evidence relating to the use of varicella vaccination in children (2). In summary:

• studies included in the review were identified by searching Medline (1966 to 2000) with the terms chickenpox, vaccination, and human, and with methodological terms to retrieve high quality controlled clinical trials and cohort studies
• data was extracted on study design, patient characteristics, vaccine dose, length of follow-up and outcomes (effectiveness of vaccine, transmission of varicella, risk of herpes, adverse reactions)
  • vaccine effectiveness
    • assessed in 10 reports from 8 randomised controlled trials (RCTs)
      • 2 RCTs showed that a single dose of varicella zoster vaccination (VZV) was effective in preventing varicella
      • 1 showed 100% efficacy at 9 months
      • 1 showed 72% efficacy at 29 months
      • 3 dose-titration RCTS supported the efficacy of the VZV is protection against varicella infection
  • adverse reactions
    • assessed in 13 reports from 12 trials
      • of trials of children
        • none showed an increase in varicella-like rash or fever from VZV over placebo
      • injection site reactions ranged from 7% to 30%
      • adverse reactions were not related to vaccine dose
      • the risk of herpes zoster in vaccinated people was assessed by 1 RCT and no zoster occurred in vaccinated or placebo groups at 9 months
• the review concluded that the evidence from randomised controlled trials supports the effectiveness of varicella vaccination in children

Reference:

• (1) Department of Health 2006. The green book - Varicella  
• (2) Skull SA, Wang EE. Varicella vaccination - a critical review of the evidence. Arch Dis Child 1001;85:83-90