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The bivalent killed whole-cell oral cholera vaccine (BivWC) is being increasingly used to prevent cholera. The presence of O-antigen-specific memory B cells (MBC) has been associated with protective immunity against cholera, yet MBC responses have not been evaluated after BivWC vaccination. To address this knowledge gap, we measured V. cholerae O1-antigen MBC responses following BivWC vaccination. Adults in St. Marc, Haiti, received 2 doses of the BivWC vaccine, Shanchol, two weeks apart. Participants were invited to return at days 7, 21, 44, 90, 180 and 360 after the initial vaccination. Serum antibody and MBC responses were assessed at each time-point before and following vaccination. We observed that vaccination with BivWC resulted in significant O-antigen specific MBC responses to both Ogawa and Inaba serotypes that were detected by day 21 and remained significantly elevated over baseline for up to 12 months following vaccination. The BivWC oral cholera vaccine induces durable MBC responses to the V. cholerae O1-antigen. This suggests that long-term protection observed following vaccination with BivWC could be mediated or maintained by MBC responses. [ABSTRACT FROM AUTHOR]

Background: Haiti's cholera epidemic has been devastating partly due to underlying weak infrastructure and limited clean water and sanitation. A comprehensive approach to cholera control is crucial, yet some have argued that oral cholera vaccination (OCV) might result in reduced hygiene practice among recipients. We evaluated the impact of an OCV campaign on knowledge and health practice in rural Haiti., Methodology/principal Findings: We administered baseline surveys on knowledge and practice relevant to cholera and waterborne disease to every 10th household during a census in rural Haiti in February 2012 (N = 811). An OCV campaign occurred from May-June 2012 after which we administered identical surveys to 518 households randomly chosen from the same region in September 2012. We compared responses pre- and post-OCV campaign. Post-vaccination, there was improved knowledge with significant increase in percentage of respondents with ≥ 3 correct responses on cholera transmission mechanisms (odds ratio[OR] 1.91; 95% confidence interval[CI] 1.52-2.40), preventive methods (OR 1.83; 95% CI 1.46-2.30), and water treatment modalities (OR 2.75; 95% CI 2.16-3.50). Relative to pre-vaccination, participants were more likely post-OCV to report always treating water (OR 1.62; 95% CI 1.28-2.05). Respondents were also more likely to report hand washing with soap and water >4 times daily post-vaccine (OR 1.30; 95% CI 1.03-1.64). Knowledge of treating water as a cholera prevention measure was associated with practice of always treating water (OR 1.47; 95% CI 1.14-1.89). Post-vaccination, knowledge was associated with frequent hand washing (OR 2.47; 95% CI 1.35-4.51)., Conclusion: An OCV campaign in rural Haiti was associated with significant improvement in cholera knowledge and practices related to waterborne disease. OCV can be part of comprehensive cholera control and reinforce, not detract from, other control efforts in Haiti.