Seropositivity and GMT of anti-PT IgG antibodies in vaccinated and unvaccinated subsets
| Vaccinated (n=94) | Unvaccinated (n=190) | P value | |
| Seropositive mothers (anti-PT IgG), n (%) | 51 (54.26) | 24 (12.63) | <0.001* |
| Seropositive infants, (n) | 51 (54.26) | 22 (11.58) | <0.001* |
| Maternal anti-PT IgG | 30.88 | 2.24 | <0.001* |
| GMT (IU/mL) (95% CI) | 21.23 to 44.91 | 1.47 to 3.91 | |
| Cord anti-PT IgG | 32.54 | 2.53 | <0.001* |
| GMT (IU/mL) (95% CI) | 22.85 to 46.33 | 1.68 to 3.81 | |
| Placental transfer ratio | 1.05 | 1.12 | 0.555 |
| Maternal anti-PT IgG titre >100 (IU/mL), n (%) | 22 (23.4) | 10 (5.26) | 0.0417* |
| Cord anti-PT IgG titre >20 (IU/mL), n (%) | 68 (72.3) | 40 (21.0) | <0.001* |
*P<0.05 considered significant
anti-PT, anti-pertussis toxin; GMT, geometric mean titre.