An open, randomised, comparative, multicentre study of the immunogenicity and safety of M-M-R™II manufactured with recombinant Human Albumin (rHA) and VARIVAX® when administered concomitantly by intramuscular (IM) route or subcutaneous (SC) route at two separate injection sites in healthy subjects 12 to 18 months of age - MMR rHA + VARIVAX IM or SC in 12-18 month-old healthy subjects