FIG. 4.

Serum anti-Vi IgG EU/ml before and after vaccination with Vi polysaccharide, as measured with the Vi bead assay. Serum samples from 996 participants were collected before (day 0) and after (day 28) vaccination with the Vi polysaccharide vaccine and tested for the presence of anti-Vi IgG with a bead immunoassay. The box represents the median and the 25th and 75th percentiles, while the whiskers the represent the largest and smallest values. *, day 28 values significantly increased compared to the day 0 values (P < 0.0001; two-tailed Mann-WhitneyU test).