Chickenpox Vaccine Combo Remains Effective For Up to 6 Years

Two doses of the measles-mumps-rubella-varicella vaccine (MMRV) and 1 dose of the live attenuated varicella vaccine (V) remain effective for up to 6 years following vaccination among children who receive them during their second year of life, according to a recent study.

A total of 5289 healthy children aged 12 to 22 months were included in phase A of the study. Each child was randomly assigned to receive either 2 doses of MMRV (n = 2279), 1 dose of combined MMR and 1 dose of monovalent varicella vaccine (MMR+V; n = 2266), or 2 doses of the MMR vaccine (control; n = 744), 42 days apart. Mean age at follow-up was 14.2 years in each cohort.
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Moderate or severe varicella was confirmed via detection of viral DNA or epidemiological link, and the severity was determined via the modified Vázquez scale. For the MMRV and MMR+V cohorts, vaccine efficacy against all and moderate to severe cases of varicella was evaluated from 6 weeks through 6 years following receipt of the second vaccine dose.

Ultimately, there had been 815 detected cases of varicella. Results of the study showed that 2 doses of MMRV were 95% effective against all cases of varicella and 99% effective against moderate to severe cases of varicella. Additionally, 1 dose of V was 67% effective against all cases of varicella and 90.3% effective against moderate to severe cases of varicella.

“Two doses of the MMRV vaccine and 1 dose of the varicella vaccine remain efficacious through 6 years post-vaccination,” the researchers concluded.

—Christina Vogt

Reference:

Henry O, Brzostek J, Czajka H, et al. One or two doses of live varicella virus-containing vaccines: efficacy, persistence of immune responses, and safety six years after administration in healthy children during their second year of life. Vaccine. 2018;36(3):381-387. https://doi.org/10.1016/j.vaccine.2017.11.081.