Oral cholera vaccine comes home

20 APR 2011

While Bangladesh surely is proud of its unique ability to contribute to global public health, ultimately people here need solutions to the health problems they face daily. That’s why it is particularly gratifying to ICDDR,B to see a vaccine with an early history in Dhaka in the early 80s return home to Bangladesh.

In recent weeks, Dukoral, an oral cholera vaccine developed by Swedish scientists Jan Holmgren and Ann-Marie Svennerholm in collaboration with ICDDR,B, was launched in Bangladesh by Healthcare Pharmaceuticals Limited (HPL). ICDDR,B played a key role in developing the vaccine, showing that the vaccine stimulated a intestinal immune response similar to the response to naturally occurring cholera. Phase one and phase 2 evaluations of the vaccine were carried out in Dhaka, and most importantly, a large phase three trial initiated in 1985 showed that the vaccine provided about 85% short term protection and about 60% protection over three years (protection among children under five lasted only about one year, suggesting booster doses may be needed for these children).

ICDDR,B is committed to developing health solutions that reach the neediest in Bangladesh, the very ones who helped test and develop these solutions. With an estimated 350,000 people requiring hospitalization for cholera in Bangladesh every year (including 100,000 treated at the ICDDR,B Dhaka Hospital annually), this vaccine could provide a major solution to a major health problem in this country and other cholera endemic areas. Thus, the question remains why it is used so rarely. Unfortunately the vaccine also has drawbacks which limit its practical application. The price is still too high to be useful in poor countries in a sustained manner. It must be kept in the refrigerator and the packaging is quite bulky limiting its distribution in the country. Finally, though rather simple for health providers to administer to patients, training and paying these health providers is a major constraint for the health system.

Though these drawbacks will limit the vaccine’s capacity to reduce the cholera burden in Bangladesh and other cholera endemic countries, the launch of Dukoral in Bangladesh is a welcome step toward the eventual control of endemic cholera. Hopefully, simpler, more convenient and less costly versions of the vaccine which can be distributed and taken more easily will soon be available. Such a vaccine was developed in Vietnam and is now being tested in India.

In addition to Dukoral, scientists at ICDDR,B are also testing another oral vaccine called Peru-15. Unlike Dukoral, Peru-15 is an attenuated live vaccine which is given orally as a single dose. Within the next few years, following additional phase two trials, it is hoped that the Centre will initiate a phase three efficacy study of this new vaccine. Though these two types of vaccines may seem to be alternative approaches, in fact, the two may both be useful in controlling cholera. The live attenuated vaccines may be especially useful for small children in routine immunization programmes or in emergency situations where a single dose is more convenient, and the killed oral vaccine may be more practical for booster doses. The next five years holds great promise for the eventual control of cholera in Bangladesh. Vaccines are not the only solution for prevention of cholera deaths; they need to be combined with improved water and sanitation and excellent treatment, but they will be an important part of an overall cholera control strategy.

For additional information on the oral cholera vaccine from the Journal of Health Population and Nutrition which is available from our web site, click here and here.