Cholera vaccine

Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.

Dukoral (Aventis Pasteur)

glass vials containing 3 mL for dilution

Approved indication: cholera immunisation

Australian Medicines Handbook section 20.1

Vibrio cholerae and Escherichia coli are responsible for many cases of diarrhoea around the world. Although cholera is endemic in some countries vaccination is not routinely recommended for travellers. Some vaccines have not been very effective.

This new product contains inactivated forms of three strains of Vibrio cholerae. It also contains a recombinant form of the binding portion of the cholera toxin. As this toxin is similar to the enterotoxin produced by the enterotoxigenic strains of Escherichia coli, the vaccine may have the ability to prevent some cases of traveller's diarrhoea.

The vial of vaccine is supplied with a sachet of sodium hydrogen carbonate which acts as a buffer. Patients dissolve the granules of the buffer in water then add the contents of the vial and drink the mixture. They should not have food or drink for one hour before and one hour after taking the mixture. The dose is repeated after at least a week, but children aged 2-6 years are recommended to have a third dose. Most people will be protected against cholera approximately one week after completing the course.

The vaccine was studied in Bangladesh as long ago as the 1980s. These studies found that for older children and adults two doses were as good as three. The protective efficacy of a two-dose regimen was 77% after a year. The protective efficacy then declines with time. If exposure to cholera continues, a booster is recommended after two years in adults and after six months in young children. Although there have been studies of the vaccine for the prevention of traveller's diarrhoea, this is not an Australian approved indication.

Patients may complain of loose stools and abdominal discomfort, but these adverse effects occur at similar frequencies in patients given a placebo. The clinical trials did not specifically assess interactions with other vaccines, but it is recommended that oral typhoid vaccines are not used within eight hours of cholera vaccine.

Although many Australians travel overseas there are only about six cases of cholera a year. The National Health and Medical Research Council advises that avoiding contaminated food and water is more important than vaccination against cholera.1 Most tourists have a low risk of infection, but the vaccine may be considered for people at high risk, for example healthcare professionals working in endemic areas or refugee camps overseas.