At the NICED Clinical Trials Unit in Kolkata, a boy participates
in an IVI study to determine if the oral killed WC cholera vaccine
elicits an immune response after a single dose.

In an effort to accelerate the use of a new oral cholera vaccine, the IVI, in collaboration with the National Institute of Cholera and Enteric Diseases (NICED), is conducting a series of studies in Kolkata, India. IVI scientists developed this vaccine, in collaboration with the Vietnamese producer VaBiotech, by reformulating a two-dose oral killed whole-cell (WC) vaccine that was initially developed in Vietnam for use in its national immunization program.

To determine if this vaccine is effective in protecting people living in high-risk areas against cholera, IVI/NICED is conducting a Phase III efficacy trial at a research site with a population of more than 110,000 in Kolkata. In this trial, about 70,000 people were given the vaccine or a placebo in August 2006 (Read a related story). Surveillance of cholera is continuing for three years following vaccination, in order to compare the incidence of cholera amongst those who received the vaccine with those  who were given the placebo, and thus to estimate the vaccine’s efficacy.

 In addition, the IVI’s Cholera Vaccine Program is conducting a small study of 160 children and adults to determine if this normally two-dose vaccine elicits a sufficient immune response after a single dose. This study is comparing the responses of people given the vaccine with those given a placebo at three points in time: before vaccination, two weeks after the first dose, and two weeks after the second dose.

Preliminary results of this study are encouraging. “If the immune response after one dose provides sufficient protection against cholera, then this vaccine may be given in a single dose and may be an appropriate tool for stopping cholera outbreaks and for establishing an international stockpile for refugee crises and other emergencies,” said Dr. Anna Lena Lopez, who leads the study. Up to now, WC vaccines have not been used for this purpose because of their regimen of two doses given 1- 4 weeks apart – too long to have an immediate impact in halting cholera outbreaks.

 
A young participant looks on as the study physician
prepares the informed consent documents.

Further studies being planned include the safety and immune response of infants to the WC vaccine when provided in the Expanded Programme of Immunization (EPI) schedule. “Providing cholera vaccine to infants through the routine immunization program will not only protect the youngest children against this disease, it will make it much easier and less costly to introduce this vaccine in cholera-endemic countries,” said IVI Director-General Dr. John Clemens.

Because this vaccine provides similar protection to the internationally available vaccine (Dukoral), but costs much less, it is an appropriate choice for developing countries. Therefore, the IVI is transferring the production technology and know-how for this vaccine to high-quality vaccine producers in India and elsewhere. It is expected that the technology transfer of this vaccine will pave the way for its licensure in India and elsewhere, where it may be used in combating this dreaded disease.