Cholera vaccine offers herd immunity, study from Zanzibar shows

"Cholera vaccine gives indirect protection to unvaccinated people in communities where a substantial fraction of the population gets the vaccine," according to a study from the island of Zanzibar in East Africa, published in the Lancet on Tuesday, NPR's "Shots" blog reports. "The effect is called 'herd immunity,'" the blog notes. According to "Shots," "half the people in six rural and urban areas received two doses of oral cholera vaccine," and "[f]or those who got it, the vaccine was 79 percent protective against the disease" while "their neighbors who didn't get vaccinated had almost as much protection."

"'This finding is good news for policymakers who have to deal with cholera in settings where ... safe water supply and adequate sanitation cannot be established in a reasonable time frame,' the study authors write" in the report, the blog notes, adding, "They say that the direct and indirect effects of cholera vaccination could eventually eliminate the disease in communities with regular vaccination programs." The blog continues, "The results give a boost to those who support much wider use of cholera vaccine in places like Haiti where cholera is endemic" (Knox, 9/4).