From the Guidelines
The second dose of the varicella vaccine should be administered at least 3 months after the first dose, and can be given to children under 4 years old who need accelerated protection, rather than waiting until age 4. This recommendation is based on the evidence from the 1 study, which suggests that the second dose of varicella vaccine can be administered prior to age 4-6 years, provided that 2-3 months have elapsed since the first dose. The first dose is typically given at 12-15 months of age, and this two-dose schedule provides optimal immunity against chickenpox, with over 98% of recipients developing adequate protection 1.
The varicella vaccine contains live attenuated virus, which stimulates the immune system to develop antibodies against the varicella-zoster virus without causing the full disease, providing long-lasting immunity and significantly reducing the risk of chickenpox infection and its potential complications 1. Early completion of the varicella vaccine series is particularly important for children with certain risk factors, including those who are immunocompromised or who may be exposed to high-risk settings.
Some key points to consider when administering the varicella vaccine include:
- The vaccine is approximately 85% effective in preventing varicella, and >95% effective in preventing severe varicella disease 1
- Breakthrough varicella disease that occurs after vaccination frequently is mild and modified 1
- The risk of herpes zoster after immunization seems to be lower than the risk of zoster after wild-type varicella infection 1
- The vaccine can be administered as a single-antigen varicella vaccine or as part of the combination MMRV vaccine 1
From the Research
Varicella Infection and Vaccination
- Varicella, also known as chickenpox, is a highly contagious infectious disease caused by the Varicella zoster virus 2.
- The disease can be treated with antiviral therapy, such as acyclovir, which has been shown to accelerate cutaneous healing and reduce fever and related constitutional symptoms in otherwise healthy children and adolescents 3.
Effectiveness of Varicella Vaccine
- A second dose of varicella vaccine was added to the routine immunization schedule for children in 2006 to address ongoing outbreaks of varicella 4.
- Studies have shown that two doses of varicella vaccine are highly effective in preventing varicella, with an effectiveness of 98.3% (95% confidence level: 83.5%-100%; P < .001) 4.
- The odds of developing varicella were 95% lower for children who received two doses compared with one dose of varicella vaccine 4.
Treatment of Varicella in Children
- Acyclovir is the drug of choice for treating varicella and herpes zoster, and can be administered intravenously or orally depending on the immunocompetence of the host 5.
- The sequential use of intravenous and oral acyclovir has been shown to be feasible and effective in treating varicella in immunocompromised children, reducing the duration of intravenous therapy and hospitalization 6.
- However, the use of acyclovir in otherwise healthy children and adolescents may not decrease the associated complications, and it is not clear whether it reduces lesions or itching due to the low certainty of the evidence 2.