It is indeed heartening news that there is now an affordable, orally administered vaccine available to tackle the unabated cholera outbreaks in developing countries.
Dr NK Ganguly, former director, Indian Council of Medical Research stated, "This is a unique vaccine. It can take care of hybrid cholera strains circulating in the atmosphere. It also has very good herd immunity -- even if the vaccine is administered among 40% of the population it will prevent spread of the disease among the rest.”
Clinical efficacy of the vaccine tested
To test the clinical efficacy of the vaccine the researchers studied a group of 67,000 people over the age of 1 year, in Kolkata, India.
Half the participants were administered the new vaccine in two doses 14 days apart, while the remaining received a placebo. The subjects were then tracked over a period of two years.
The researchers observed that the vaccine after the trial and the evaluation period provided over 70 percent protection, which did not decline over two years.
Only 20 episodes of cholera occurred in the vaccine group as opposed to 68 cases in the placebo group. In children aged one to five, the most susceptible to the disease, the risk fell by around 50 percent.
In addition, no adverse effects linked to the vaccine were reported.
According to the researchers, the "trial shows that the modified killed-whole-cell oral vaccine is safe and efficacious, providing nearly 70 percent protection against clinically significant cholera for at least 2 years after vaccination.”
Benefits of the vaccine
The vaccine is simple, easy to administer and can be delivered orally through a syringe. It is well adapted and cost effective.
It is also innovative, incorporating all the important genes
required to make it very selective and more effective without harming the intestines in any way.
Saranya Sridhar, from the University of California in Berkeley stated, "This success story ought to be an example for other vaccine initiatives, especially against malaria and HIV, to similarly engage industry and academia towards solving an urgent public health need."
However, he added, "Today's encouraging results must be tempered by cautious optimism as results from longer follow-up for evidence of lasting protection must be reviewed before this current vaccine is recommended as an alternative to the expensive [vaccine]".
The findings of the study are published in the journal Lancet.
Cholera the food-and-water borne disease
Cholera is an acute food and water-borne infection caused by the enterotoxin subunit-A of Vibrio cholerae.
The disease constitutes a major health problem in developing countries and is rampant in regions with poor sanitation and food and water hygiene.
Severe cholera infection has a mortality rate of 30-50 percent. Although oral cholera vaccines are safe, immunogenic and effective, clean water and sanitation are the best preventive measures to combat the disease.
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