Method of treatment

A method of immunising against Neisseria meningitidis infection, comprising the steps of:

• (a) immunising a human patient at a first age of between 0 and 6 months with a bacterial saccharide conjugate vaccine comprising bacterial saccharides each separately conjugated to tetanus toxoid carrier proteins, wherein the bacterial saccharides consist essentially of (i) a N. meningitidis serogroup C (MenC) capsular saccharide and a Haemophilus influenza (Hib) saccharide or (ii) a N. meningitidis serogroup C (MenC) capsular saccharide, a N. meningitidis serogroup Y (MenY) capsular saccharide and a Haemophilus influenza (Hib) saccharide, wherein the tetanus toxoid carrier protein is present at a total TT content of 5-40 idg per dose, wherein the bacterial saccharide conjugate vaccine is co-administered with a first vaccine comprising diphtheria, tetanus, and acellular pertussis antigens (DTPa);
• and
• (b) immunising the human patient at a second age of between 13 and 20 months with a Neisseria meningitidis conjugate vaccine comprising N. meningitidis serogroup A capsular saccharide (MenA), N. meningitidis serogroup C capsular saccharide (MenC), N. meningitidis serogroup W135 capsular saccharide (MenW135), and N. meningitidis serogroup Y capsular saccharide (MenY) conjugated separately to a tetanus toxoid carrier protein which is present at a total dose of 30-80 μg, wherein the Neisseria meningitidis conjugate vaccine is co-administered with a second vaccine comprising DTPa,
• wherein co-administration of the Neisseria meningitidis conjugate vaccine with the vaccine comprising DTPa in step b) results in an at least 10% increase in immunogenicity against at least one of MenA, MenC, MenW135, and MenY compared to where the Neisseria meningitidis conjugate vaccine is administered alone, measured by Serum Bacteriocidal Assay (SBA).