Povey M, et al. - Researchers performed a phase 3b follow-up of an observer-blinded, randomised, controlled trial to determine the 10-year vaccine efficacy of two doses of a combined measles-mumps-rubella-varicella vaccine (MMRV), one live attenuated varicella vaccine (V) dose given after one measles-mumps-rubella vaccine (MMR) dose (MMR + V), vs two MMR doses (control vaccine) for the prevention of confirmed varicella. In phase a, random assignment was done of children aged 12–22 months (at first vaccination) from Czech Republic (Czechia), Greece, Italy, Lithuania, Norway, Poland, Romania, Russia, Slovakia, and Sweden, to receive two doses of MMRV, one dose of MMR and one dose of varicella vaccine, or two doses of MMR, 42 days apart via computer-generated randomisation list. Outcomes suggest that for the prevention of varicella, optimum long-term protection was achieved with a two-dose schedule of varicella vaccine. This vaccine offers individual protection against all severities of disease and leads to a potential reduction in transmission, as observed in the US experience with universal mass vaccination.