TABLE 2

Comparison of immune response to the Vi capsular polysaccharide vaccine and the control hepatitis A vaccine in children between the ages of 2 and 16 years in Karachi and Kolkata

VariablesValues for children receiving the indicated vaccineP
ViHepatitis A
Overall (age 2–16 yr)
    Blood sample 1, day 0 (prevaccination)a
        No.153147
        GMCb (95% confidence limits)83.2 (78.4–88.4)81.8 (77.2–86.7)0.692
        Attained protective antigen level (n [%])c12 (7.8)10 (6.8)0.723
    Blood sample 2, 6 wk since vaccination
        No.123120
        GMC (95% confidence limits) (ELU/ml)1,428.3 (1130–1805.4)85.9 (78–94.6)<0.001
        Attained protective antigen level (n [%])117 (95.1)9 (7.5)<0.001
        Achieved a ≥4-fold rised (n [%])104 (86.7)2 (1.7)<0.001
    Blood sample 3, 2 yr since vaccination
        No.7168
        GMC (95% confidence limits) (ELU/ml)262.6 (190–362.8)90.4 (79.1–103.4)<0.001
        Attained protective antigen level (n [%])40 (56.3)8 (11.8)<0.001
        Achieved a ≥4-fold rise (n [%])27 (39.1)4 (6.1)<0.001
Age <5 yr
    Blood sample 1, day 0 (prevaccination)
        No.6052
        GMC (95% confidence limits) (ELU/ml)75 (75–75)76.2 (73.8–78.7)0.304
        Attained protective antigen level (n [%])0 (0.0)1 (1.9)e
    Blood sample 2, 6 wk since vaccination
        No.4239
        GMC (95% confidence limits) (ELU/ml)832.2 (546–1268.5)82.7 (67.8–100.8)<0.001
        Attained protective antigen level (n [%])36 (85.7)1 (2.6)<0.001
        Achieved a ≥4-fold rise (n [%])29 (70.7)1 (2.7)<0.001
    Blood sample 3, 2 yr since vaccination
        No.2119
        GMC (95% confidence limits) (ELU/ml)133.4 (93.7–190)96.5 (67–139)0.218
        Attained protective antigen level (n [%])8 (38.1)2 (10.5)0.071
        Achieved a ≥4-fold rise (n [%])5 (25.0)2 (11.1)0.379
Age 5–15.9 yr
    Blood sample 1, day 0 (prevaccination)
        No.9395
        GMC (95% confidence limits) (ELU/ml)89 (80.8–98.1)85.1 (77.9–92.9)0.497
        Attained protective antigen level (n [%])12 (12.9)9 (9.5)0.463
    Blood sample 2, 6 wk since vaccination
        No.8181
        GMC (95% confidence limits) (ELU/ml)1,890 (1447.3–2468.1)87.5 (78.5–97.6)<0.001
        Attained protective antigen level (n [%])81 (100.0)8 (9.9)e
        Achieved a ≥4-fold rise (n [%])75 (94.9)1 (1.3)<0.001
    Blood sample 3, 2 yr since vaccination
        No.5049
        GMC (95% confidence limits) (ELU/ml)348.9 (230.2–528.8)88.2 (77.3–100.5)<0.001
        Attained protective antigen level (n [%])32 (64.0)6 (12.2)<0.001
        Achieved a ≥4-fold rise (n [%])22 (44.9)2 (4.2)<0.001
  • a Blood sample 1 is from day 0 (prevaccination), 2 is from week 6 since vaccination, and 3 is from year 2 since vaccination.

  • b GMC, geometric mean concentration. All values are expressed in ELU/ml.

  • c Attained protective antigen level (Vi, ≥150 ELU/ml [GSK in-house standard]). We used the value 75 ELU/ml (midpoint) for those listed as <150 ELU/ml in the report.

  • d Achieved a ≥4-fold rise in antibodies, in relation to baseline, as detected in the cited blood sample.

  • e P value is not possible due to 0 in one of the cells.