A reformulated oral vaccine against cholera promises to be an affordable and effective weapon to combat the disease for people living in endemic areas of developing countries, according to a new study.
The internationally licensed cholera vaccine currently available is too expensive for use in developing countries, where it is most needed.
Vietnam produces its own two-dose oral cholera vaccine and distributes it through its public health system at US$0.40 a dose. Nine million doses have been delivered so far.
To kick-start the process of scaling up this vaccine in developing countries around the globe, the vaccine was reformulated to comply with WHO standards.
Researchers from India, Korea and Sweden conducted a pilot trial of the vaccine at Kolkota's Infectious Diseases Hospital in eastern India. Cholera is endemic in Kolkota.
The study evaluated the vaccine's safety and efficacy outside Vietnam.
Participants were healthy and included 101 adults aged 18–40 years and 100 children aged 1–17 years. They received two random doses of either the vaccine or a placebo, 14 days apart.
After immunization, 53 per cent of the adults and 80 per cent of the children showed at least a four-fold increase in their antibody levels against Vibrio cholerae O1, the predominant strain of cholera-causing bacteria.
Safety tests revealed that "no adverse event occurred more frequently in the vaccinated than in the placebo group", say the researchers.
"Cholera affects a large number of children in developing countries, and so a vaccine that is safe and effective for children sounds impressive, and the development as a whole appears to be a step towards global rolling out of the cholera vaccine," says Sumana Kanjilal, associate professor of paediatric medicine at Calcutta National Medical College Hospital, India.
The reformulated vaccine is now undergoing a trial in around 70,000 people in Kolkata. "If the vaccine is found to be safe and protective, this could pave the way for the use of this vaccine in the control of cholera worldwide," the researchers write.
PLoS ONE doi 10.1371/journal.pone.0002323 (2008)