CD79A and infection: Similar anti-Vi IgG immune responses to TCV have previously been reported in studies from Vietnam and India.9, 10 In a study evaluating the antibody response to Vi-polysaccharide and Vi-conjugate vaccines in a typhoid fever controlled human infection model, there were high anti-Vi IgG and IgA responses to TCV, and anti-Vi IgA antibodies were associated with protection in individuals who received TCV.16