A study released today shows that an oral cholera vaccine made in India is the first such vaccine to offer significant protection for 5 years, while another new report says the vaccine was well-accepted in an immunization campaign last year in the African country of Guinea.
The vaccine, Shanchol, is made by Shantha Biotechnics and was endorsed by the World Health Organization in 2011. It is a modified version of an earlier vaccine, Dukoral, made by the Swedish company SBL Vaccin AB.
Control of cholera has relied mainly on sanitation and safe drinking water. Despite the availability of cholera vaccines in recent years, concerns about cost, acceptability, and implementation have discouraged their use, as noted in the new reports.
The 5-year vaccine trial was conducted by a large international team in a slum area of Kolkata, India. The researchers used a double-blind, placebo controlled design to assess the vaccine's efficacy in preventing cholera severe enough to require treatment in people at least 12 months old.
Residents in 3,933 Kolkata dwellings were randomly assigned (by dwelling) to receive two doses of the vaccine or a preparation of killed Escherichia coli K12 as a placebo.
Over 5 years, cholera was confirmed in 69 of 31,932 vaccine recipients and in 219 of 34,968 placebo recipients, or 2.2 cases per 1,000 in the vaccine group and 6.3 per 1,000 in the placebo group. The cumulative protective efficacy of the vaccine was 65% (95% confidence interval, 52%-74%; P<.0001), and year-by-year estimates showed no evidence of a decline in efficacy, the report says.Shanchol was also tried experimentally in Haiti last year, amid some controversy. I covered it from late 2011 through May 2012 but I haven't heard much follow-up on that effort.