Cholera vaccine seen safe, effective in India-study

An India-made cholera vaccine that meets World Health Organization (WHO) standards has proven to be safe and effective in young children in a part of India where the disease is endemic, a new study says.

The researchers, who published their study results in The Lancet [1], hope the vaccine can soon be rolled out in developing countries where cholera remains endemic.

The trial involved 107,774 participants in Kolkata in eastern India, half of whom were given the vaccine and the other half a placebo. The vaccine was orally administered in two doses, at least 14 days apart [between July and September 2006] , and the researchers tracked the participants for two years.

On average, there were 20 episodes of cholera in the vaccine group and 68 episodes in the placebo group, which meant the vaccine had a protective efficacy rate of 67 percent, the researchers said. There were no adverse events linked to the vaccine.

“This … 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,” wrote the researchers, led by John Clemens at the International Vaccine Research Institute (IVI) in Seoul, South Korea. “Protection was seen in children vaccinated at ages under 5 years, as well as in older individuals.”

An earlier version of this vaccine has been used in Viet Nam. Though it is effective, it has never been approved for use elsewhere because the manufacturing process in Viet Nam did not reliably remove cholera toxin from the vaccine, the researchers said. Furthermore, Vietnam’s national regulatory authority is not WHO-approved.

IVI worked with Vietnamese manufacturer VaBiotech to improve the vaccine and production has since been transferred to vaccine maker Shantha Biotechnics in Hyderabad in India, where the national regulatory authority is WHO-approved.

Cholera causes 120,000 deaths every year worldwide, according to the WHO.

The study was funded by the Bill & Melinda Gates Foundation, Swedish International Development Cooperation Agency, Governments of South Korea, Sweden, and Kuwait.

[1] Dipika Sur, M. … [et al.] (2009). Efficacy and safety of a modified killed-whole-cell oral cholera vaccine in India: an interim analysis of a cluster-randomised, double-blind, placebo-controlled trial. The Lancet, Early Online Publication, 9 October 2009. doi:10.1016/S0140-6736(09)61297 [Free registration required].

See also: Sanitation vs. vaccination in cholera control, Sanitation Updates, 15 May 2009

Source: Tan Ee Lyn, Reuters, 08 Oct 2009

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