Comparison of the IgG response to gSG6, fSG6 or their combination. Box plot of OD values among responders to the three antigens in the different surveys as indicated. Box plots, whiskers and dots as in Figure 3. P value was determined according to Friedman test. Pairwise comparisons by the Wilcoxon matched-pairs signed rank test (two-tailed). Number of responders (n) and mean age in years ± 95% CI (in parentheses) were as follows: Aug '94, n = 46 (13.7 ± 3.7); Oct '94, n = 48 (15.9 ± 4.1); Mar '95, n = 28 (14.6 ± 6.3).