IFNG and infection: Once infection occurs, T‐cells transform into a group of effector T‐cells that can quickly acquire and expand the effector function after antigen re‐exposure, ultimately surviving long‐term and providing continual immunity.[33] In this study, we found that the recombinant tetanus vaccine induced significantly more specific CD4+ T‐cells than the TT vaccine, especially in the IFN‐γ T‐cell response.