It consists of a killed whole-cell V. cholerae O1 with purified recombinant B-subunit of cholera toxoid. Trials have been performed in Bangladesh, Peru and Sweden. Trials have shown that this vaccine is safe and offers 85-90% protection during six months in all age groups after administration of two doses, one week apart. In Bangladesh protection declined after six months in young children, however it was still about 60% effective in older children and adults after two years.
Variant WC/rBS vaccine
This variant does not contain recombinant B-subunit and has been produced and tested in Vietnam. It must be given in two doses, on week apart. A trial conducted in 1992-1993 in Vietnam showed efficient protective of 66% up to eight months. However this vaccine is only licensed in Vietnam.
CVD 103-HgR vaccine
This vaccine consists of a weakened live oral genetically modified V. cholerae O1 strain. Trials performed in several countries proved that a single dose is safe. The efficacy has been investigated in adult volunteers in the US where it has been found that a single dose offers 95% protection against V. cholerae and 65% protection again V. cholerae El Tor following a challenge given three months after administration.
A trial performed in Indonesia has not shown convincing protection in a population exposed to cholera a long time after immunisation.
(Source: World Health Organisation)