The invention provides two batches of a vaccine, wherein: (a) each of the batches of vaccine comprises: a conjugate of a capsular saccharide from serogroup C of Neisseria meningitidis and one or both of: (i) a conjugate of a capsular saccharide from serogroup W135 of Neisseria meningitidis and/or (ii) a conjugate of a capsular saccharide from serogroup Y of Neisseria meningitidis (b) the concentration of conjugated serogroup C saccharide in the first batch is C1 (c) the concentration of conjugated serogroup C saccharide in the second batch is C2 if applicable, (d) the concentration of conjugated serogroup W135 saccharide in the first batch is W1 if applicable, (e) the concentration of conjugated serogroup W135 saccharide in the second batch is W2 if applicable, (f) the concentration of conjugated serogroup Y saccharide in the first batch is Y1 if applicable, (g) the concentration of conjugated serogroup Y saccharide in the second batch is Y2 and wherein (h) the ratios C1/C2, W1/W2 and Y1/Y2 are each between 0.90 and 1.10.
