The present invention relates a combination for use in the treatment and/or prevention of mastitis containing i) an agonistic anti-CD40 monoclonal antibody or a CD40 ligand or a vector coding for the anti-CD40 antibody or a vector coding for the CD40L and ii) inactivated or attenuated bacteria selected from the group consisting of Staphylococcus, Streptococcus, Listeria or Escherichia.