Table 3.

Estimated Protection Conferred by a Single Dose of Killed Oral Cholera Vaccine

Study	Site (Study Year), Study Design	Vaccine	Study Population and Number of Participants	Primary Assessment of Protection (Clinical Endpoints and Definitions)	Total Number of Cholera Cases and Serotypes and Biotypes	Vaccine Protection after 1 Dose (95% Confidence Interval)	Duration of Follow-up (Months)
Wierzba, 2015	Odisha, India (2011), test-negative design	Bivalent OCV (Shanchol)	Of 51488 eligible residents of the study area, 31552 (61%) received at least 1 dose and 23751 (46%) received 2 doses	Compare odds of having been vaccinated between cholera cases and test- negative controls • Cases were diarrhea patients found positive for Vibrio cholerae • Controls were diarrhea patients negative for V. cholerae infection	44 patients included in the analysis • 44 (100%) O1 Ogawa, of which 34 (77%) were El Tor variant and 10 (23%) were hybrid (El Tor/classical) biotypes	• 33% (−318 to 89)	24
Ivers, 2015	Haiti (2012), case-control design with bias-indicator study	Bivalent OCV (Shanchol)	45417 people were vaccinated in the campaign, 91% of whom received both doses	Compare odds of having been vaccinated between cholera cases and matched controls • Cases were diarrhea patients with a stool sample positive for V. cholerae O1 • Controls were individuals who did not seek treatment for diarrhea between the first day of study enrollment and the date of onset of symptoms in their corresponding case, matched to each case by location of residence, enrollment time (within 2 weeks of the case), and age group (1–4 years, 5–15 years, and >15 years)	48 patients (1 excluded from the analysis due to lost data) • 36 (37%) O1 Ogawa • 11 (23%) O1 Inaba	• 67% (–62 to 93)	23
Khatib, 2012 [27]	Zanzibar (2008), cohort design with bias indicator study	Monovalent OCV that contains the recombinant B subunit (Dukoral)	Of 48178 eligible residents of the study area, 23921 (50%) received 2 complete doses of vaccine	Compare incidence of cholera in recipients of the vaccine and nonrecipients	42 patients included in the primary analysis • 42 (100%) O1 El Tor Ogawa	• 46% (–80 to 83)	14
Luquero, 2014	Boffa and Forecariah, Guinea (2012), case-control design with bias-indicator study	Bivalent OCV (Shanchol)	Target population was163000 people in Boffa district and 46000 people in parts of Forecariah; coverage with at least 1 dose was 92% in Boffa and 71% in Forecariah	Compare odds of having been vaccinated between cholera cases and matched controls • Cases were diarrhea patients with a stool sample positive for V. cholerae O1 • Controls were neighbors of the case who did not seek treatment for diarrhea between the first day of study enrollment and the date of onset of symptoms in their corresponding case, matched to each case by age group (1–4, 5–9, 10–19, 20–29, 30–39, or ≥40 years)	40 patients included in the primary analysis; of the 36 for whom a specimen was sent for culture and PCR analysis: • 18 (50%) O1 El Tor Ogawa; • 13 had positive results of culture and PCR • 5 had positive PCR results but negative culture results	• 66% (−53 to 93) based on culture or PCR positive cholera • 43% (−84 to 82) based on RDT positive cholera	6
Qadri, 2016 [28]	Bangladesh (2013), randomized, control trial	Bivalent OCV (Shanchol)	204700 persons underwent randomization, received 1 dose, and were included in the analysis (102552 received vaccine and 102148 received placebo)	Compare incidence of cholera in randomly assigned recipients of vaccine and placebo	101 cholera cases included in the analysis: • 100 (99%) O1 El Tor Ogawa • 1 (1%) O1 El Tor Inaba	• 40% (11 to 60) against all cholera episodes • 63% (24–82) against severely dehydrating cholera • 56% (16 to 77), 63% (−39 to 90), and 16% (49 to 53) against all cholera episode among persons vaccinated at the age of ≥15 years, 5–14 years, and 1–4 years, respectively	6
Azman, 2016 [34]	Juba, South Sudan (2015), case-cohort study	Bivalent OCV (Shanchol)	Juba was estimated to have between 500 000 and 1 million inhabitants with massive population movements because of civil strife; 140249 doses were administered in targeted areas of Juba [11]	Compare hazard ratios of cholera between unvaccinated and vaccinated persons	34 cholera cases included in the analysis	• 87% (70–100)	2

See References Listed in Supplementary Data.

Abbreviations: OCV, oral cholera vaccine; PCR, polymerase chain reaction; RDT, rapid diagnostic test.