A Study of Swine-origin A/H1N1 Influenza Vaccines in Healthy Europeans Children Aged 6 to 35 Months

The purpose of this study is to generate data on immunogenicity and safety of the monovalent H1N1 vaccine in support of the development and registration. Primary objectives: * To describe the immune response to vaccines 21 days after each vaccination in all participants. * To describe the antibody persistence eight months after the first vaccine administration using hemagglutination inhibition (HAI) method in a subset of participants who received two half-doses of either formulation 1 or 2. * To describe the immune response against the A/H1N1 strain using the HAI method 21 days after last vaccination with the 2010-2011 NH seasonal Trivalent Influenza Vaccine (TIV) administered 13 months after the first vaccination in a subset of subjects who received two half-doses of either t either formulation 1 or 2 of the A/H1N1 influenza vaccines as primary series. * To describe the safety profile of each vaccine in all participants.