An Age-stratified, Randomized Immunogenicity Trial of Killed Oral Cholera Vaccine with Delayed Second Dose in Cameroon

Jérome Ateudjieu, David A. Sack, Sonia Sonkeng Nafack, Shaoming Xiao, Ketina Hirma Tchio-Nighie, Herve Tchokomeni, Landry Beyala Bita'a, Paul Ntsekendio Nyibio, Etienne Guenou, Kedia Mayah Mondung, Frank Forex Kiadjieu Dieumo, Rosanne Minone Ngome, Kelsey N. Murt, Malathi Ram, Mohammad Ali, Amanda K. Debes

Research output: Contribution to journalArticlepeer-review


The recommended schedule for killed oral cholera vaccine (OCV) is two doses, 2 weeks apart. However, during vaccine campaigns, the second round is often delayed by several months. Because more information is needed to document antibody responses when the second dose is delayed, we conducted an open-label, phase 2, noninferiority clinical trial of OCV. One hundred eighty-six participants were randomized into three dose-interval groups (DIGs) to receive the second dose 2 weeks, 6 months, or 11.5 months after the first dose. The DIGs were stratified into three age strata: 1 to 4, 5 to 14, and . 14 years. Inaba and Ogawa vibriocidal titers were assessed before and after vaccination. The primary analysis was geometric mean titer (GMT) 2 weeks after the second dose. Data for primary analysis was available from 147 participants (54, 44, and 49 participants from the three DIGs respectively). Relative to the 2-week interval, groups receiving a delayed second dose had significantly higher GMTs after the second dose. Two weeks after the second dose, Inaba GMTs were 55.1 190.3, and 289.8 and Ogawa GMTs were 70.4, 134.5, and 302.4 for the three DIGs respectively. The elevated titers were brief, returning to lower levels within 3 months. We conclude that when the second dose of killed oral cholera vaccine was given after 6 or 11.5 months, vibriocidal titers were higher than when given after the standard period of 2 weeks. This provides reassurance that a delayed second dose does not compromise, but rather enhances, the serological response to the vaccine.

Original languageEnglish (US)
Pages (from-to)974-983
Number of pages10
JournalAmerican Journal of Tropical Medicine and Hygiene
Issue number5
StatePublished - Nov 2022

ASJC Scopus subject areas

  • Parasitology
  • Infectious Diseases
  • Virology


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