This neutralizes the action of the diphtheria toxin and reduces tissue damage. The early immunization of children against diphtheria has reduced the number of cases seen in adults to a handful each year. These infections predominantly occur in individuals not previously immunized. The second injection is administered four to eight weeks after the first, and the third injection is administered six to 12 months after the second. Diphtheria vaccine is administered by intramuscular injection, usually in the large muscle of the shoulder.
Adverse reactions are usually mild and include redness and swelling at the site of injection.
Since diphtheria antitoxin is derived from horses, the patient must receive a skin test to rule out any sensitivity to the vaccine.