TABLE 2.
Proportions of individuals for serogroups A, C, Y, and W135 by age group with serum bactericidal antibody titers of ≥8 before and 1 month following vaccination with tetravalent polysaccharide vaccine and ≥fourfold increases pre- to postvaccination
| Serogroup | Age group (mo) | No. of individuals/no. of individuals tested (%)
|
McNemar's exact P value for change from pre- to postvaccination | ||
|---|---|---|---|---|---|
| SBA titer of ≥ 8 prevaccination | SBA titer of ≥ 8 1 mo postvaccination | ≥Fourfold increase pre- to postvaccination | |||
| A | 6 | 3/37 (8) | 7/37 (19) | 6/30 (20) | 0.13 |
| 12 | 10/39 (26) | 12/42 (29) | 6/35 (17) | 0.63 | |
| 18 | 12/43 (28) | 19/45 (42) | 11/39 (28) | 0.15 | |
| 24 | 29/65 (45) | 41/51 (80) | 23/49 (47) | <0.001 | |
| 36 | 34/75 (45) | 56/64 (88) | 37/62 (60) | <0.001 | |
| 48 | 47/86 (55) | 67/71 (94) | 47/68 (69) | <0.001 | |
| C | 6 | 3/41 (7) | 5/43 (12) | 5/40 (13) | 0.73 |
| 12 | 2/42 (5) | 5/44 (11) | 4/40 (10) | 0.38 | |
| 18 | 1/43 (2) | 5/47 (11) | 4/41 (10) | 0.13 | |
| 24 | 5/68 (7) | 25/59 (42) | 22/59 (37) | <0.001 | |
| 36 | 4/79 (5) | 29/71 (41) | 28/71 (38) | <0.001 | |
| 48 | 8/90 (9) | 40/84 (48) | 36/81 (44) | <0.001 | |
| W135 | 6 | 0/43 (0) | 5/43 (12) | 5/42 (12) | 0.063 |
| 12 | 1/45 (2) | 6/46 (13) | 5/45 (11) | 0.22 | |
| 18 | 2/49 (4) | 9/49 (18) | 8/49 (16) | 0.04 | |
| 24 | 4/68 (6) | 32/68 (47) | 32/68 (47) | <0.001 | |
| 36 | 4/78 (5) | 42/76 (55) | 39/76 (51) | <0.001 | |
| 48 | 11/92 (12) | 55/89 (62) | 50/88 (57) | <0.001 | |
| Y | 6 | 2/40 (5) | 6/41 (15) | 5/37 (14) | 0.063 |
| 12 | 5/44 (11) | 6/43 (14) | 5/41 (12) | 1.00 | |
| 18 | 2/45 (4) | 9/47 (19) | 9/43 (21) | 0.07 | |
| 24 | 14/67 (21) | 32/60 (53) | 26/59 (44) | <0.001 | |
| 36 | 28/77 (37) | 46/71 (65) | 34/69 (49) | <0.001 | |
| 48 | 35/92 (38) | 74/85 (87) | 63/84 (75) | <0.001 | |