Q. Is there any blood test that can determine whether or not I have adequate anti-tetanus antibody levels in my blood?
A. The response to vaccines is often assessed by measuring the appearance and concentration of specific antibodies in blood. With some vaccines (and toxoids), the mere presence of antibodies is not sufficient to ensure clinical protection, but rather a minimal circulating level of antibody is required (e.g., 0.01 IU/mL of tetanus antitoxin).
An ELISA test can accurately measure the anti-tetanus antibody levels, and consequently the level of protection. However, this is not done as a routine and is only be available at few research laboratories.