Diphtheria antibody titer considered optimally protective is
High-Yield Explanation
Diphtheria antibody titer considered as optimally protective is >0.1 IU/ml. Titers of IgG antibody against diphtheria toxoid vaccine reflect various levels of protection against the disease as follows: <0.01 IU/ml: No protection 0.01 IU/ml: Basic protection >0.1 IU/ml: Optimal protection. Ref: Textbook of microbiology; Ananthanarayan and paniker's; 10th Edition; Pg; 245