The purpose of the study is to evaluate the immune response of toddlers, to a booster dose in the second year of life of two meningococcal C conjugated polysaccharide vaccine, and to assess the interchangeability of the two different vaccines.

Children 14 to 18 months of life, previously vaccinated with 2 doses of tetanus toxoid conjugated polysaccharide men C vaccine or three doses of the CRM197 conjugated polysaccharide men C vaccine before 7 months of age, are randomized to receive any of the two vaccines. Serum antibody activity against meningococcus C will be measured inmediately before and 4 weeks after the booster dose. Children will also be vaccinated with a combined vaccine containing DTaP+IPV+Hib.

Inclusion Criteria:

• Healthy toddlers of both sexes
• Toddlers of 14 to 19 months of age (including the day that the toddler is 14 and the day before he is 19 months of age)
• Children previously vaccinated with two doses of polysaccharide meningococcal C vaccine conjugated to tetanus toxoid or three doses of polysaccharide meningococcal C conjugated to CRM197 before 7 month of age.
• Informed consent signed by one or both parents who are adequately informed about the study.

Exclusion Criteria:

• Toddlers with severe diseases or axilar temperature ≥ 38,0ºC at inclusion time
• Toddlers with severe chronic diseases
• Toddlers who have received any other vaccine within the last month or with a programmed vaccination within the 28 subsequent days after the administration of the vaccine of study.
• Toddlers with clinical or bacteriological diagnosis of previous meningococcal disease.
• Toddlers with hypersensitivity to any of the components of the vaccines to study or antibiotics used during the manufacturing process that could be present as non- detectable traces (streptomycin, neomycin, polymyxin B).
• Toddlers with personal history of convulsions.
• Toddlers with known bleeding disorder no controlled
• Toddlers with known congenital or acquired immunodeficiency
• Toddlers who are receiving or have been received any treatment that could change the immune response (administration of intravenous immunoglobulin, systemic corticosteroids or haemoderivates) within the 3 previous months.
• A toddler that under investigator opinion is probable to be lost during the follow-up
• A toddler that is currently included or is planned to be included in any other clinical trial.
• A toddler that under investigator opinion must not be included in the study due to other medical or social reasons.