CIAO3 and tetanus: One month after the third primary vaccination dose, all infants in both groups had antibody levels above the seroprotective thresholds of anti-diphtheria (anti-D), anti-tetanus (anti-T), anti-PRP, and anti-poliovirus types 1 and 2 antibodies, and antibody levels above the seropositive thresholds of anti-PT, anti-FHA, anti-PRN antibodies.