Nutritional Advice El Mondo
Objectives:
Killed whole-cell oral cholera vaccines (kOCVs) are becoming a standard cholera control and prevention tool. However, vaccine efficacy and direct effectiveness estimates have varied, with differences in study design, location, follow-up duration and vaccine composition posing challenges for public health decision making. Therefore, this review article (meta-analysis) has been conducted.
Do 2 doses of killed whole-cell oral cholera vaccine provide sufficient protection against cholera?
Study design:
This review article included 7 RCTs with 695 patients with cholera and 6 observational studies (4 case-control studies,1 cohort study and 1 case-cohort study) with 217 patients with cholera).
The duration between the first two vaccine doses in RCTs ranged from 14 to 42 days.
The duration between the two primary vaccine doses in observational studies ranged from 12 to 25 days.
There were no signs of publication bias from a visual assessment of funnel plots for observational studies and RCTs, separately.
Results and conclusions:
The investigators found in pooled analyses an average two-dose efficacy of 58% [95% CI = 42-69, I2 = 58%] and effectiveness of 76% [95% CI = 62-85, I2 = 0%].
The investigators found in pooled analyses an average two-dose efficacy in children younger than 5 years [30%, 95% CI = 15-42, I2 = 0%] was lower than in those 5 years or older [64%, 95 CI = 58-70, I2 = 0%, p 0.0001].
The investigators found in pooled analyses two-dose efficacy estimates of kOCV were similar during the first 2 years after vaccination, with estimates of 56% [95% CI = 42-66, I2 = 45%] in the first year and 59% [95% CI = 49-67, I2 = 0%] in the second year. However, the efficacy reduced to 39% [95% CI = 13 to 57, I2 = 48%] in the third year and 26% [95% CI = -46 to 63, I2 = 74%] in the fourth year.
The investigators concluded 2 kOCV doses provide protection against cholera for at least 3 years. Children younger than 5 years were observed to have lower efficacy than those aged 5 years and older. Although vaccination alone will probably not lead to elimination of cholera, it can provide an important stopgap while improved water, sanitation and health-care infrastructure are provided to vulnerable populations. More work is needed to understand how and when to best use existing vaccines and to design new and more effective ones. However, the past three decades of evidence points towards kOCV being a safe, effective, and important tool to fight cholera.
Original title:
Protection against cholera from killed whole-cell oral cholera vaccines: a systematic review and meta-analysis by Bi Q, Ferreras E, […], Azman AS.
Link:
http://www.thelancet.com/pdfs/journals/laninf/PIIS1473-3099(17)30359-6.pdf
Additional information of El Mondo:
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