Evaluation of a single dose of diphtheria toroid among adults in the Republic of Georgia, 1995: Immunogenicity and adverse reactions

To determine the immunogenicity and safety of a single dose of diphtheria toroid among adults, blood samples for detecting serum antitoxin levels were obtained from 18- to 59-year-old subjects (n = 248) before and 30 days after immunization with Td (tetanus-diphtheria toxoids; manufactured by Serum Institute of India), By day 30, the seroprevalence of antitoxin levels greater than or equal to 0.1 IU/mL increased from 22.6% to 81.5%; median antitoxin levels increased from 0.01 to 4.0 IU/mL. These parameters were lowest among subjects who were 40-59 years old, especially among those 40-49 years old. Adverse reactions (local redness, swelling, induration, fever >39 degrees C) were reported by 5.3% of participants, Our findings suggest that, in general, one dose of the Indian-produced Td vaccine is efficacious and safe in inducing an adequate immune response against diphtheria in adults; however, in Georgia, persons 40-59 years old, especially those 40-49 years old, will require additional doses of toroid to achieve protective levels of antitoxin.