Cholera vaccines provide substantial protection for adults, but provide significantly less protection for children under age five, according to a recent study conducted by researchers at the Johns Hopkins University Bloomberg School of Public Health.
The study, which was published in a recent issue of the journal The Lancet Infectious Diseases, considered a total of seven clinical trials and six observational studies which revealed that the standard two-dose regimen for cholera vaccination reduced the risk of being infected with the disease by 58 percent on average for adults, but only 30 percent for children under age five.
To better understand the effectiveness of oral cholera vaccines, the most-common preventative treatment for the disease, Andrew Azman, research associate at Johns Hopkins’ Department of Epidemiology, and his coworkers from the Oral Cholera Vaccine Working Group of the Global Task Force on Cholera conducted a literature examination and meta-analysis of vaccine efficacy in randomized clinical trials and observational studies.
The results they found, specifically the seven clinical trials and six observational studies, all involved the three major commercial vaccines currently in use.
An examination of the studies revealed that the two-dose regimen efficacy for adults was approximately 58 percent with a 76 percent effectiveness. However, efficacy was found to be substantially lower in children under five at approximately 30 percent.
A single dose of the vaccine also appeared to provide a similar protection level as the two-dose regimen, at least within six months following vaccination.
According to Johns Hopkins, the findings could inform policymakers on how and when to use the vaccine, particularly in outbreak settings such as the ongoing epidemic in Yemen, which has seen an estimated 400,000 suspected cases since and 1,900 deaths since the outbreak began in April.
“In cholera-prone areas, public health decision makers don’t always have the luxury of caring about the outbreak risk in two years,” Azman said. “They care about the risk of transmission tomorrow or in two weeks or next month. Being able to vaccinate twice the number of people with a limited quantity of vaccine can be very important.”
Cholera is a small intestine infection caused by Vibrio cholerae and is spread most commonly through contaminated water and food that has come into contact with human feces containing the bacteria. Symptoms typically include diarrhea, vomiting, muscle cramps, dehydration, and electrolyte imbalance. According to the National Institutes of Health, approximately 28,000 patients succumb to the disease’s lethal effects each year.