Typhoid vaccine shows promise
POSTED July 25, 2009 - 15:21 | POSTED BY Neharika Sabharwal
Last edited by Priya Markanda on July 25, 2009 - 16:30
The non-profit International Vaccine Institute (IVI) in collaboration with the National Institute of Cholera and Enteric Diseases in Kolkata, India, conducted a two-year trial of the vaccine Vi polysaccharide, in India's slum districts.
The study and its results
The test was conducted in two wards of an Indian slum with a population of 60,000 people, to establish the effectiveness of the vaccine in children aged two to five years.
Participants either received the Vi vaccine or an inactivated hepatitis A vaccine. Each of the participants was monitored for two years.
Researchers found that the vaccine was 61 percent effective in preventing typhoid fever. Among the children who received the vaccine, the rate was nearly 80 percent positive. For the unvaccinated neighbors who were in contact with the immunized children, the vaccine offered 44 percent protection.
According to researchers when enough people are vaccinated, the spread of a disease through a community declines, even though everyone has not received the shot.
"The protection for children under the age of 5 years is important because this age group has been shown to be at high risk for typhoid fever in many areas where the disease is endemic," said Dr. John Clemens, Director-General of the IVI and an international expert in vaccine evaluation.
About typhoid
Typhoid is a potentially deadly disease and is caused by Salmonella typhi bacteria. It spreads through contaminated food and water or close contact with someone who is infected.
Symptoms of the disease include high fever, weakness, profuse sweating, diarrhea and stomach pains. Dehydration over time can result in delirium and then death.
Typhoid fever affects about 22 million people a year in the developing world and between 200,000 and 600,000 die each year from the disease.
Cheap and effective vaccine
Even though safe and effective vaccines exist, few of them are available for the poor and destitute.
The Vi polysaccharide, is a perfect typhoid vaccine in developing countries because it is cheap (about $.50 per dose) and requires only a single dose.
The IVI laboratories have tripled the manufacturing of the low-cost vaccine, which is expected to further reduce the vaccine's production cost.
The study was funded by the Bill and Melinda Gates Foundation and coordinated by the Seoul-based International Vaccine Institute.
Results of the study were published in Thursday's New England Journal of Medicine.
