LANCET : A SINGLE DOSE ORAL VACCINE FOR CHOLERA

Prof .DRRAM,HIV /AIDS,HEPATITIS ,SEX DISEASES & WEAKNESS expert,New Delhi,India, 

Cholera continues to harm the most vulnerable people worldwide. Diarrhoeal diseases are a major source of preventable morbidity and mortality, and in 2015 claimed the lives of more than 1·3 million people, of whom 499 000 were children younger than 5 years.

         As a contributor to the global burden of diarrhoeal disease, Vibrio cholerae is a particularly harsh pathogen, causing rapid onset of severe nausea, vomiting, and profuse watery diarrhoea that can lead to death within hours—even of the healthiest young adults. Whole communities can be rapidly affected in epidemics, causing both physical harm and psychological distress. The pervasive social determinant of the problem—poor or no access to safe water, sanitation, and hygiene—means that displaced people, refugee populations, and those in conflict zones are at risk of major outbreaks of the illness. Cholera also continues to occur routinely, regularly, and with great impact (although often with less media attention) in endemic countries, such as Bangladesh and now Haiti, where children and the poorest people are the most at risk of being harmed. In both epidemic and endemic circumstances, the public health role of cholera vaccination has been re-emerging with interest from policy makers over the past 8 years.

        In The Lancet Infectious Diseases, Firdausi Qadri and colleagues4 describe results of 2 years of follow-up of a large, randomised, double-blind, placebo-controlled efficacy trial of a single dose of an inactivated whole-cell oral cholera vaccine (OCV) in Bangladesh. They found that a single dose provided protection for at least 2 years when given to adults (vaccine protective efficacy against all cholera episodes 59%, 95% CI 42–71) and to children aged 5 years or older (52%, 8–75). The findings make an important contribution to cholera control around the world, and could help to take us one step closer to WHO's ambitious goal of reducing deaths from the disease by 90% by 2030.

      However, a single dose of OCV did not protect children younger than 5 years compared with placebo (vaccine protective efficacy against all cholera episodes −13%, 95% CI −68 to 25),4 consistent with the 6-month results of the same study.12 Other studies show some, but reduced, protection of two doses of OCV in this age group as well, which has implications for strategies on the use of OCV in highly endemic regions where young children are an important risk group. Further studies are needed to determine how best to protect the youngest individuals, and to identify the ideal dosing schedule of the vaccine.