The invention relates to a vaccine against N. meningitidis infections, comprising (i) an N. meningitidis LOS especially consisting of a lipid A, an inner core, and an L8-type a chain in which the heptose II residue of the inner core (a) carries a phosphoethanolamine (PEA) substituent in position 0-3, and does not carry a PEA substituent in positions 0-6 and O-7, or (b) carries a phosphoethanolamine (PEA) substituent in position 0-3 and in position 0-6 or 0-7 and (ii) the lipidated sub-unit B (TbpB) of the receptor of the human transferrine of an N. meningitidis strain or a lipid fragment of said TbpB.
