title: An Open Label Non-inferiority Trial Assessing Vibriocidal Response of a Killed Bivalent Oral Cholera Vaccine Regimen following a Five Year Interval in Kolkata, India.
abstract: BACKGROUND
  The bivalent killed oral cholera vaccine (OCV) provides 65% cumulative protection over five years. It remains unknown whether a boosting regimen can maintain protection in previously immunized populations. This study examines the immunogenicity and safety of an OCV regimen given five years following initial dosing.
  
  
  RESULTS
  An open label controlled trial was conducted in 426 healthy Indian participants previously enrolled in a large efficacy trial. To assess whether an OCV regimen given after five years can elicit an antibody response equal to that of a primary series, we compared vibriocidal antibody titers in previously immunized participants receiving a two dose booster regimen to participants receiving a primary two dose immunization series. Among participants receiving a two dose primary series of OCV (n = 186), 69% (95% CI 62%-76%) seroconverted. In the intervention arm (n = 184), 66% (95% CI 59%-73%) seroconverted following a two dose boosting schedule given five years following the initial series. Following a single boosting dose, 71% (95% CI 64%-77%) seroconverted. Children demonstrated 79% (95% CI 69%-86%) and 82% (95% CI 73%-88%) seroconversion after primary and boosting regimens, respectively.
  
  
  CONCLUSIONS
  Administration of an OCV boosting regimen elicits an immune response similar to those receiving a primary series in endemic areas. Though a single boosting dose induces a strong immune response, further investigations are needed to measure if these findings translate to clinical protection.
authors.affiliation: National Institute of Cholera and Enteric Diseases, Kolkata, India.
authors.forename: Suman
authors.initials: S
authors.lastname: Kanungo
authors.affiliation: International Vaccine Institute, Seoul, Republic of Korea.
authors.forename: Sachin N
authors.initials: SN
authors.lastname: Desai
authors.affiliation: National Institute of Cholera and Enteric Diseases, Kolkata, India.
authors.forename: Jayanta
authors.initials: J
authors.lastname: Saha
authors.affiliation: National Institute of Cholera and Enteric Diseases, Kolkata, India.
authors.forename: Ranjan Kumar
authors.initials: RK
authors.lastname: Nandy
authors.affiliation: National Institute of Cholera and Enteric Diseases, Kolkata, India.
authors.forename: Anuradha
authors.initials: A
authors.lastname: Sinha
authors.affiliation: International Vaccine Institute, Seoul, Republic of Korea.
authors.forename: Deok Ryun
authors.initials: DR
authors.lastname: Kim
authors.affiliation: International Vaccine Institute, Seoul, Republic of Korea.
authors.forename: Barnali
authors.initials: B
authors.lastname: Bannerjee
authors.affiliation: National Institute of Cholera and Enteric Diseases, Kolkata, India.
authors.forename: Byomkesh
authors.initials: B
authors.lastname: Manna
authors.affiliation: International Vaccine Institute, Seoul, Republic of Korea.
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Yang
authors.affiliation: National Institute of Cholera and Enteric Diseases, Kolkata, India; Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Ali
authors.affiliation: National Institute of Cholera and Enteric Diseases, Kolkata, India; PATH India Office, New Delhi, India.
authors.forename: Dipika
authors.initials: D
authors.lastname: Sur
authors.affiliation: International Vaccine Institute, Seoul, Republic of Korea.
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Wierzba
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000097:blood*; D002648:Child; D002771:Cholera / Q000276:immunology / Q000517:prevention & control*; D022121:Cholera Vaccines / Q000008:administration & dosage* / Q000276:immunology; D015331:Cohort Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007117:Immunization, Secondary / Q000592:standards*; D007194:India; D008297:Male; D014611:Vaccination; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000276:immunology; D014734:Vibrio cholerae / Q000276:immunology*; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D022121:Cholera Vaccines; D015164:Vaccines, Inactivated