Table 2.
Titers of antibodies against Haemophilus influenzae type b capsular polysaccharide (PRP) associated with long-term protection against invasive disease (≥ 1 μg/mL) and against upper respiratory tract colonization by Hib in unvaccinated (Kangaba) and vaccinated (Bamako) populations, by age group
| Age Group | Antibody titers ≥ 1 μg/mL | P* | Antibody titers ≥ 5 μg/mL | P* | ||
|---|---|---|---|---|---|---|
| Kangaba | Bamako | Kangaba | Bamako | |||
| 6 mos. (N = 30) | 13.3% | 90.0% | < 0.0001 | 0.0% | 66.7% | < 0.0001 |
| 12 mos. (N = 30) | 16.7% | 93.3% | < 0.0001 | 0.0% | 46.7% | < 0.0001 |
| 15 mos. (N = 30) | 16.7% | 76.7% | < 0.0001 | 0.0% | 50.0% | < 0.0001 |
| 18 mos. (N = 30) | 10.0% | 83.3% | < 0.0001 | 0.0% | 56.7% | < 0.0001 |
| 23 mos. (N = 30) | 23.3% | 93.3% | < 0.0001 | 0.0% | 40.0% | < 0.0001 |
*
One-sided P value from Fisher's exact test.