TLDR, it's complicated
Cholera is one of the severe forms of acute diarrhoeal disease that can be fatal within hours if not treated promptly.1 In 2024, among 33 countries across five WHO regions, 733โ956 cholera cases were identified and 5162 people died from this disease. Importantly, there was 1ยท25-times increase in the number of cholera cases in Africa from 2022 to 2023.2 Nevertheless, compared with 2023, the incidence of cholera was 37% higher and cholera-associated deaths were 27% higher, relative to 2024. With the prevailing surge in both cholera incidence and mortality and emerging outbreaks of cholera in so many countries, in addition to better access to water and sanitation for populations of all ages, there is an urgent need for an effective and widely available cost-efficient vaccine against cholera.
In The Lancet Global Health, Hanmeng Xu and colleagues3 published a systematic review and meta-analysis to understand the current evidence on the protection provided by killed whole-cell oral cholera vaccines (kOCVs). To generate this work, they identified randomised trials and observational studies that reported estimates of protection conferred by kOCVs against medically attended confirmed cholera in children and adults. The systematic review included five randomised controlled trials (RCTs) and ten observational studies that revealed an average two-dose efficacy 1 year after vaccination of 55% (95% CI 46โ62), declining to 44% (25โ59) 5 years after vaccination, and an average two-dose effectiveness 1 year after vaccination of 69% (58โ78), declining to 47% (9โ70) 5 years after vaccination. On the other hand, the efficacy of these average two doses in children younger than 5 years was found to be half that of people aged 5 years and older. Importantly, the systematic review and meta-analysis identified only one randomised trial on one dose of kOCV over 2 years, which revealed sustained protection (52%, 95% CI 8โ75). This is a positive finding because WHO currently recommends one dose of kOCV in outbreak response for short-term protection.
Also
Thus, several actions need to be considered to make cholera vaccine more effective and accessible to vulnerable populations. More work needs to be done to specifically identify the people who would most likely benefit from kOCVs. In future, rigorous studies should focus on identifying the high-risk factors and comorbidities that are associated with a higher burden of cholera, which might help in the design of more effective cholera vaccines for such a population. Children with malnutrition have the lowest protection against cholera5 because of a diminished acidic barrier in their stomachs; they are the childhood population most vulnerable to infection with bacteria,6 especially with symptomatic cholera, and they are more prone to die within a short period of the development of symptomatic cholera because of rapidly evolving hypovolemic shock. Thus, the efficacy of cholera vaccines in individuals with comorbidities needs to be explored. Whether the use of kOCVs could potentially help save costs for hospitals, communities, and patients also needs to be discussed.