New cholera vaccine trialed in Bangladesh slum cut cases by nearly 40 per cent

Firdausi Qadri of the worldwide Centre for Diarrhoeal Disease Research in Dhaka, Bangladesh, said the trial results, published in The Lancet journal, show how a routine oral cholera vaccination programme “could substantially reduce the burden of disease and greatly contribute to cholera control efforts”.

There are only two licensed vaccines for cholera: Shanchol and Dukoral. Cholera is an infectious disease that causes acute watery diarrhoea, which spreads from person to person through water or food contaminated by Vibrio cholerae bacteria. The subjects varied in age, going as low as one year old, but all were at high risk of contracting cholera because of poor sanitation and overcrowding. However, the World Health Organization could not possibly distribute the vaccine to as many people as these are costly and must be taken with a large glass of buffer solution.

When given as part of routine health services, the vaccine, which consists of a two-dose regimen that now costs $3.70, could help control the disease in the more than 50 countries, mostly in Asia and Africa, where it is endemic, the researchers say. Cholera kills some 91,000 of the 2.8 million people it affects in endemic regions each year.

The vaccine, Shanchol, “is cheap”, she added.

Public health experts in Bangladesh, however, had earlier warned the government against any move to include cholera vaccine in the routine immunisation drive.

The incidence of cholera decreased by 45 percent in the group that received both vaccination and hand-washing-water treatment intervention.

The study shows that even with moderate vaccination coverage, cases of severe life-threatening cholera were reduced by almost 40 per cent.

For individuals who were vaccinated, it was shown to confer 53 percent protection two years after the vaccine was administered, the study said.

There were no serious adverse effects, the team reported.

“Ultimately, the key to controlling cholera is clean water and adequate sanitation, which half the developing world (approximately 2.5 billion people) lack, but this remains a rather hard reality for the world’s poorest nations as well as those affected by climate change, war, and natural disasters”, Qadri said.

In a related commentary, Maureen O’Leary and Kim Mulholland from the London School of Hygiene and Tropical Medicine said that the cholera vaccine has “great potential for aiding disease control”, but emphasized the need to assess the duration of the protection as well as evaluate its cost-effectiveness. “It should not supersede efforts to reduce risky behaviors, and to improve sanitation and provide safe drinking water to people living in cholera-endemic areas”.