*Maternal antibody may have contributed to a portion of the total antibody.

Another clinical study to evaluate serological responses and adverse reactions of AvP's DT was performed in 40 children under one year of age. One group of 20 children received 0.5 mL doses of DTP,DT,DTP at two, four and six months of age, respectively. The second group of 20 children received 0.5 mL doses of DTP, DTP, and DT, respectively, at the same ages.⁴

The immunologic protection as measured by toxin neutralization induced by DT was comparable when administered as either a second or third dose (TABLE 2).⁴

TABLE 2⁴ NUMBER (PERCENT) OF CHILDREN PROTECTED FOLLOWING ADMINISTRATION OF THREE DOSES

The reaction rates following AvP whole-cell DTP vaccination closely correlated with the rates observed with other commercially available whole-cell DTP vaccines.⁵ The incidence of adverse reactions was significantly lower following DT administration (p < 0.05).Although the number of vaccinees was small, no persistent screaming episodes or severe neurological reactions such as seizures or encephalopathy were observed with either vaccine in this study.⁴

As with any vaccine, vaccination with DT may not protect 100% of susceptible individuals.

Tetanus is an intoxication manifested primarily by neuromuscular dysfunction caused by a potent exotoxin elaborated by Clostridium tetani.

The occurrence of tetanus in the US has decreased dramatically from 560 reported cases in 1947 to a record low of 48 reported cases in 1987. Tetanus in the US is primarily a disease of older adults. Of 99 tetanus patients with complete information reported to the Centers for Disease Control and Prevention (CDC) during 1987 and 1988,68% were ≥50 years of age, while only six were < 20 years of age. Overall, the case-fatality rate was 21%.² In 1992, 45 cases were reported of which 82% were ≥50 years of age.⁶ The disease continues to occur almost exclusively among persons who are unvaccinated or inadequately vaccinated or whose vaccination histories are unknown or uncertain.²

In 4% of tetanus cases reported during 1987 and 1988,no wound or other condition was implicated. Non-acute skin lesions, such as ulcers, or medical conditions such as abscesses, were reported in association with 14% of cases.²

Spores of C. tetani are ubiquitous. Serologic tests indicate that naturally acquired immunity to tetanus toxin does not occur in the US.² Thus, universal primary vaccination, with subsequent maintenance of adequate antitoxin levels by means of appropriately timed boosters, is necessary to protect persons among all age-groups. Tetanus toxoid is a highly effective antigen, and a completed primary series generally induces protective levels of neutralizing antibodies to tetanus toxin that persist for ≥10 years.²

The potency of diphtheria and tetanus toxoids was determined on the basis of immunogenicity studies with a comparison to a serological correlate of protection (0.01 antitoxin units/mL) established by the Panel on Review of Bacterial Vaccines & Toxoids.⁷

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