Oral Vaccines for Preventing Cholera

Summary

A Cochrane review [Abstract] 1 included 5 efficacy trials with a total of 462 754 participants. A whole-cell plus recombinant vaccine (WC-rBS vaccine [Dukoral]) from Peru and a whole-cell vaccine (BivWC [Shancho]) vaccine from India and Bangladesh were assessed. 2 doses of Dukoral with or without a booster dose reduces cases of cholera at two-year follow-up in children and adults (overall vaccine efficacy [VE] 76%, RR 0.24, 95% CI 0.08 to 0.65; 2 trials, n=16 423). 2 doses of Shanchol reduces cases of cholera at one-year follow-up (VE 37%; RR 0.63, 95% CI 0.47 to 0.85; 2 trials, n=241 631), at 2 years (VE 64%; RR 0.36, 95% CI 0.16 to 0.81; 2 trials, n=168 540), and at 5 years (VE 80%; RR 0.20, 95% CI 0.15 to 0.26; 1 trial, n=54 519).A single dose of Shanchol reduces cases of cholera at six-month follow-up (VE 40%), and at 2 years (VE 39%).A single dose of Shanchol reduces cases of severe dehydrating cholera at six-month follow-up (VE 63%) and at 2 years (VE 50%).

A meta-analysis 2 included 7 trials (n=695) and 6 observational studies (n=217), with an average two-dose efficacy of 58% (95% CI 42 to 69, I²=58%) and effectiveness of 76% (95% CI 62 to 85, I²=0). Average two-dose efficacy in children younger than 5 years (30%, 95% CI 15 to 42, I²=0%) was lower than in those 5 years or older (64%, 95% CI 58 to 70, I²=0%; p<0.0001). Two-dose efficacy estimates were similar during the first 2 years after vaccination, with estimates of 56% (95% CI 42 to 66, I²=45%) in the first year and 59% (95% CI 49 to 67, I²=0) in the second year. The efficacy reduced to 39% (13 to 57, I²=48%) in the third year, and 26% (-46 to 63, I²=74%) in the fourth year.