A few years later, when it was feared that the new V. cholerae O139 serogroup might outcompete the O1 serogroup as the main cause of cholera, and a bivalent O1/O139 WC-BS OCV formulation developed in Sweden had been found to be safe and induce intestinal IgA and serum vibriocidal antibody responses also against the O139 component [23], we helped Vietnam to reformulate its OCV to also include formalin-killed O139 strain (the 4260B strain tested in Sweden). This evidence concerns the gene CD79A and vibrio infectious disease.