Oral vaccines for preventing cholera

Area of Science:

• Public Health
• Infectious Disease Epidemiology
• Vaccinology

Background:

• Cholera causes acute watery diarrhea, leading to dehydration and death if untreated.
• Epidemics of cholera are linked to poverty and poor sanitation.
• Effective, affordable, and easily administered vaccines are crucial for cholera prevention.

Purpose of the Study:

• To evaluate the effectiveness of oral cholera vaccines in preventing cholera cases.
• To assess the safety profile of oral cholera vaccines.
• To determine the impact of oral cholera vaccines on cholera-related mortality.

Main Methods:

• Systematic review and meta-analysis of randomized and quasi-randomized controlled trials.
• Inclusion of seven large efficacy trials, four artificial challenge studies, and 29 safety trials.
• Data extraction and risk of bias assessment by two independent reviewers.

Main Results:

• Killed whole-cell oral cholera vaccines demonstrated 52% efficacy in year one and 62% in year two.
• Efficacy was lower in children under 5 years (38%) compared to older individuals (66%).
• No significant increase in adverse events was observed with killed whole-cell vaccines compared to placebo.

Conclusions:

• Currently available oral killed whole-cell cholera vaccines offer moderate protection against cholera episodes for up to two years.
• Vaccine impact and cost-effectiveness depend on cholera prevalence, epidemic frequency, and access to rehydration therapy.
• Live attenuated cholera vaccines are still under development, with limited data on efficacy and effectiveness.