BACKGROUND: Annual influenza vaccination provides an opportunity to administer a booster dose of diphtheria, tetanus, acellular pertussis and inactivated poliomyelitis vaccine (Tdap-IPV) to the elderly. This study evaluated immune responses to and safety of the two vaccines administered concomitantly or sequentially to elderly individuals in France and Germany.
METHODS: Individuals aged ≥60 years who had received a diphtheria/tetanus booster within 5-15 years were randomised (1:1) to receive either Tdap-IPV and an inactivated influenza vaccine concomitantly (Group 1) or inactivated influenza vaccine then Tdap-IPV 28-35 days later (Group 2). Antibody titres were measured before and 28-35 days after each vaccination.
RESULTS: The mean age of randomised individuals (n=954) was 68.8 years. Post-vaccination seroprotection rates (≥0.1IU/mL for diphtheria/tetanus and ≥8 1/dilution for polio) for Group 1 were non-inferior to Group 2 for diphtheria (85.4% vs. 87.5%), tetanus (both 100%), polio type 1 (99.8% vs. 100%), polio type 2 (both 100%) and polio type 3 (99.3% vs. 99.8%). Similarly, percentages of vaccines with pertussis antibodies ≥5EU/mL for Group 1 were non-inferior to Group 2: pertussis toxin (94.3% vs. 98.1%), filamentous haemagglutinin (99.8% vs. 100%), pertactin (97.3% vs. 96.0%), fimbriae 2 and 3 (91.7% vs. 89.5%). Post-vaccination geometric mean titres of anti-influenza haemagglutinin antibodies for Group 1 were non-inferior to Group 2. Adverse events following administration of Tdap-IPV were similar in both study groups, with no vaccine-related serious adverse events.