Antibody responses to live and killed poliovirus vaccines in the milk of Pakistani and Swedish women.

The effect of poliovirus vaccination on mucosal immunity was studied in lactating women because secretory IgA antibodies to poliovirus in milk may reflect intestinal immunity. Swedish mothers lacked significant titers of secretory IgA antibodies in their milk before vaccination. Subcutaneous vaccination with killed poliovirus vaccine resulted in low but transient increases in titers of secretory IgA antibodies in the milk of most of these women. Pakistani mothers had significant titers of secretory IgA antibodies in their milk before immunization; these titers increased after subcutaneous poliovirus vaccination in 45% of the women. Peroral vaccination of Pakistani women with liver poliovirus vaccine diminished already existing titers of secretory IgA antibodies in their milk. The decrease in titer was especially pronounced when the liver poliovirus vaccine was given together with a subcutaneous vaccine consisting of killed Vibrio cholerae organisms; the mean titer of secretory IgA antibodies in milk 14 days after vaccination was about 40-fold lower than it was before vaccination.