Healthy children aged 12-22 months were randomised ( 3:3:1 ratio , by computer-generated randomisation list , with block size seven ) to receive 42 days apart ( 1 ) two doses of MMRV ( MMRV group ) , or ( 2 ) MMR at dose one and monovalent varicella vaccine at dose two ( MMR+V group ) , or ( 3 ) two doses of MMR ( MMR group ; control ) .