Oral vaccines for preventing cholera

Oral killed whole cell vaccines appear to be effective and appear to prevent 50 to 60% of cholera episodes during the first two years compared with placebo.

Comment: The quality of evidence is downgraded by study limitations (incomplete follow-up for efficacy).

Summary

A Cochrane review included 7 large efficacy trials, 4 small artificial challenge studies, and 29 safety trials . Five variations of a killed whole cell vaccine have been evaluated in large scale efficacy trials (4 trials, n=249 935). The overall vaccine efficacy during the first year was 52% (95% CI 35% to 65%), and during the second year was 62% (95% CI 51% to 62%). Protective efficacy was lower in children aged less than 5 years; 38% (95% CI 20% to 53%) compared to older children and adults; 66% (95% CI 57% to 73%). One trial of a killed whole cell vaccine amongst military recruits demonstrated 86% protective efficacy (95% CI 37% to 97%) in a small epidemic occurring within 4 weeks of the 2-dose schedule (n=1426). Efficacy data is not available beyond two years for the currently available vaccine formulations, but based on data from older trials is unlikely to last beyond three years. The safety data available have not shown any clinically significant increase in adverse events compared to placebo.

Clinical comments

Date of latest search: 8 February 2011

Ədəbiyyat

1. Sinclair D, Abba K, Zaman K et al. Oral vaccines for preventing cholera. Cochrane Database Syst Rev 2011;(3):CD008603.