[Efficacy and side effects following immunization with Salmonella typhi Vi capsular polysaccharide vaccine]

Efficacy and side effects following the immunization with Salmonella typhi Vi capsular polysaccharide vaccine (Vi) were assessed. The diluted solution (DS) of Vi was used as placebo. A total number of 777 children and adults were observed for side effect response. Mild and moderate fever appeared 16.93% and 0.05% in Vi group, 15.01% and 0.03% in DS group, respectively (statistically significant). Two cases with mild local reaction were observed in Vi group. A total number of 81,506 vaccinees were investigated on the efficacy of Vi vaccine, using positive blood culture of Salmonolla typhi as a diagnostic criterion. The protective rate and index of vaccine were 71.35% and 3.49% respectively. If 2 cases of positive Widal's test were included in, the protective rate would come up to 78.17% with a protective index 4.85. Clinical data showed that fever seen in the cases in Vi group was much lower than that of DS group. The systematic and local reaction of Vi vaccine were mild. The vaccine is safe and has high protective rate. It can also decrease the degree of fever with only one single dose as primary immunization. We believe Vi vaccine may serve as a vaccine of new generation to be promoted.