Mogode OCV Booster dose Study (MOBS)

Problem statement: Oral cholera vaccine (OCV) protects for 3 to 5 years. The Cholera Roadmap suggests repeating vaccination after this interval; however, it is not known the number of vaccine doses to be used. Specific Aim: Determine if persons who received previous doses of OCV respond to a single dose of OCV with a booster response 2 or 3 years after the initial doses. Hypothesis. An initial immunization with two doses of OCV will prime individuals so that a single dose 2 to 3 years after the initial vaccinations will stimulate a booster response. Evidence of a booster response will be observed as an early rise in serum vibriocidal and IgA/IgG titers (day 4 or 5) following the single dose. Proposed Study. Subjects who had received zero, one or two doses of OCV during the Mogode 2017 OCV campaign will be given a single dose of OCV. Serum samples will be obtained prior to the dose, and on days 4 or 5, 7, and 14 (half on day 4/half on day 5). The subjects will be age stratified into 3 groups (1-4, 5-14, >14 years) and according to whether they had received zero, 1 or 2 doses earlier.