WASHINGTON — The safety profile of Aventis Pasteur's reduced-antigen tetanus-diphtheria acellular pertussis vaccine in adolescents is similar to that of the currently-licensed tetanus-diphtheria vaccine, Michael E. Pichichero, M.D., reported at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
Adacel (reduced-antigen tetanus-diphtheria acellular pertussis or Tdap) is licensed in Canada for booster immunization of adolescents and adults. It is under review by the Food and Drug Administration for use in individuals 11–64 years.
Two randomized multicenter U.S. trials included 2,990 adolescents aged 11–17 who received Tdap and 792 given tetanus-diphtheria toxoid (Td), said Dr. Pichichero, a pediatric infectious diseases specialist in Rochester, N.Y.
Immediate reactions (within 30 minutes) were reported at comparably low frequencies in both the Tdap and Td groups (0.5%-0.6%). Most reactions were mild and resolved within a day. Also comparable were the frequency, intensity, and mean duration of fever of 38° C or greater and injection site erythema and/or swelling.
Injection site pain was slightly but significantly more frequent in the Tdap group (79.2% vs. 71.0%), but this pain was usually of mild intensity and its mean duration did not differ significantly between the two groups, Dr. Pichichero said.
Postvaccination limb circumference measurements within 2 weeks of vaccination were similar between the two groups (increases of more than 3 cm occurred in roughly 5% of each group), and no study subjects had whole arm swelling. Headache, generalized body ache, and tiredness were the three most commonly reported solicited systemic events, all in less than 30% of each group.