CIAO3 and infection: DiphtheriaSeronegative: Anti-DT < 0.01 IU/mL Seroprotective: Anti-DT ≥ 0.1 IU/mL TetanusSeronegative: Anti-TT titers < 0.01 IU/mL Seroprotective: Anti-TT titers ≥ 0.1 IU/mL PertussisSeropositive:Anti-PT, anti-FHA (filamentous hemagglutinin), and anti-Prn (pertactin) titers ≥ 5 IU/mL. Pertussis infection or vaccination in the past two years: Anti-PT titers ≥ 50 IU/mL Recent infection or vaccination:Anti-PT titers ≥ 100 IU/mL