41 lactating Pakistani women were vaccinated orally with Salmonella typhi vaccine alone or in combination with parenteral Vibrio cholerae whole cell vaccine, in order to study the possible difference in the secretory response after live and inactivated vaccines. The antibody response in saliva, milk and serum was recorded using the enzyme-linked immunosorbent assay, ELISA. All had prevaccination antibody levels against the 2 vaccines. The live S. typhi vaccine gave a serum IgG and IgA response but did not influence the IgM levels. Salivary or milk secretory IgA (SIgA) antibody levels showed both increases and decreases but in most cases remained unchanged. Even if the vaccine was given in enteric coated capsules, the milk and salivary SIgA response was more often decreased than increased, although somewhat higher serum IgG levels were attained with this preparation. Parenteral cholera vaccination enhanced both serum and SIgA milk antibody response. Combination of the 2 vaccines did not have any untoward effect on the antibody response in serum or in secretions against V. cholerae or S. typhi LPS. The results show that an oral vaccine often induces a rather poor, or even negative mucosal antibody response, while a parenteral vaccine provokes a substantial SIgA response in individuals orally primed by natural exposure. This is in agreement with our previous findings with oral and parenteral poliovirus vaccines in this population.
Administration, Oral Cholera Vaccines