Breastfeeding linked to the reduction of both rotavirus shedding and IgA levels after Rotarix® immunization in Mexican infants

The overall rotavirus IgA geometric mean titers (GMT) increased significantly post dose 2 from post dose 1 [176 (95%CI: 113-273) to 335 (238-471); p = 0.020). Infants who were exclusively/predominantly breastfed were less likely to shed vaccine virus in stool than those who were formula-fed (22% vs. 43%, p = 0.016). Infants who were breastfed had lower rotavirus IgA titers than those who were formula-fed after dose 1 [GMT: 145 (84-250) vs. 267 (126-566) p = 0.188] and dose 2 [236 (147-378) vs.578 (367-910), p = 0.007]. Infants who shed vaccine virus post dose 1 had significantly higher serum IgA GMT than those who did not shed [425 (188-965) vs. 150 (84-266), p = 0.038]. Breastfeeding was linked with the reduction of both stool vaccine shedding, and IgA seroresponse. The reduced rotavirus replication in the gut and shedding after dose 1 may explain in part the lower IgA response in serum.