Comparative safety of tetanus-diphtheria toxoids booster immunization in students in Grades 6 and 9

Background. Tetanus-diphtheria toxoids (Td) booster immunization is general ly recommended for Grade 9 students (14- to 16-year-olds) but targeting you nger students may enhance vaccine uptake or facilitate simultaneous vaccina tions, However, earlier vaccination might cause greater side effects. This study was undertaken to compare the safety of Td vaccinations in students i n Grade 6 (11 to 12 years old) and Grade 9, Methods. A controlled, sequential assessment of Td vaccine, adsorbed, was c onducted in one urban school district, starting with Grade 9 students. Grad e 6 students were given Td concurrently with Dose 3 of hepatitis B vaccine. Adverse effects were assessed during visits 2 days after vaccination, Part icipation criteria, immunization technique and assessment procedures were s tandardized. Results. Of 410 students vaccinated, 204 in Grade 9 and 206 in Grade 6, 391 (95.4%) were assessed in person, Nineteen missed follow-up visits but tele phone interviewers established that none missed school because of vaccine s ide effects, At follow-up Grade 6 students more often reported deltoid pain with arm movement (35.2% vs. 10.8%, P < 0.001), Injection site redness gre ater than or equal to 50 mm in diameter was present in 12.2% of Grade 6 and 3.6% of Grade 9 students (P < 0.001) whereas swelling greater than or equa l to 50 mm diameter was present in 22.4 and 10.8%, respectively (P < 0.01), Fewer than 10% of subjects took analgesics for injection site pain. Only 5 students (1.3%) rated Td site morbidity as severe/unacceptable, Hepatitis B site morbidity was minimal in comparison, Conclusion. Td boosters were moderately reactogenic in adolescents. Younger students more often experienced injection site morbidity but considered it bearable. Booster immunizations can reasonably be offered within the age r ange of 11 to 16 years.