Cholera vaccination campaigns may reduce cases

Two studies released this week have shown that launching cholera vaccination campaigns in response to cholera outbreaks, in addition to rehydration and sanitation, may be an effective method of reducing the number of cases and deaths.

While the World Health Organization believes that this reactive cholera vaccination should be considered during outbreaks, it cautions that the data for this approach is scarce, CIDRAP News reports.

The first study was a small case-controlled study from an outbreak in Vietnam in 2008 where vaccination was found to highly effective. The report notes that oral cholera vaccines had only been used once before as an outbreak response in Micronesia in 2000 and it showed to be effective. That vaccine, CVD-103HgR, was found to be ineffective in a controlled trial, however, and it is no longer made.

Dukoral, manufactured by Crucell, is the only cholera vaccine that is internationally licensed. The vaccine was given to eight case patients and 16 members of the control group. It was found to be 76 percent effective.

The second study was conducted by a team of researchers from all around the world and estimated that a vaccine that was 85 percent effective for six months would have cut deaths by 40 percent during a Zimbabwe epidemic from August 2008 to July 2009, CIDRAP News reports.

In an editorial that accompanied the two studies, Edward T. Ryan of Massachusetts General Hospital and Harvard University said that these new studies are significant and that they may play a part on short and long-term response plans. That role, CIDRAP News reports, is currently unclear.

"We have a wily and adaptive foe that has changed the rules of engagement repetitively, and it may be time for us to similarly adapt our strategies," Ryan said, according to CIDRAP News.