- Campaign vaccinates 50,000 residents highly vulnerable to outbreaks
  in Zanzibar
- Project aims to find evidence for best use of oral cholera vaccines in
  African settings

A boy accompanied by his family drinks oral cholera
vaccine at a village in Zanzibar, Tanzania in January 2009.

The IVI is working with the World Health Organization (WHO) and the Ministry of Health and Social Welfare of Zanzibar to immunize around 50,000 residents with an oral cholera vaccine in Zanzibar, Tanzania as part of a project to help determine the best use of oral cholera vaccines in sub-Saharan Africa. The IVI is responsible for assessing the effectiveness of the vaccine, administered through a mass vaccination campaign led by Zanzibar’s Ministry of Health and Social Welfare and WHO.

With assistance of the Swiss Tropical Institute (STI), the project is evaluating a new-generation vaccine – Dukoral® –that has been licensed in more than 33 countries worldwide and is widely used by international travelers. Funding for the project comes from the Bill & Melinda Gates Foundation through a grant to WHO to study the use of cholera vaccines in vulnerable populations.  Part of the IVI’s work is also funded by the Swedish International Development Agency (SIDA) and LG Electronics, the Korea-based conglomerate.

Around 50,000 people living in high-risk areas of Zanzibar were vaccinated, starting on January 17, 2009. The second dose of the two-dose regimen of the vaccine was given during February 7-16, 2009. Diarrheal disease surveillance at study sites will continue for one year after the vaccination to assess the vaccine’s effectiveness, including evaluation of indirect (herd) protection among people in the community who have not received the vaccine.

Local residents queue to be vaccinated with the
oral cholera vaccine in Zanzibar, Tanzania in January 2009.

The archipelago of Zanzibar is about 50 kilometers east of mainland Tanzania. Since the 1970s, Zanzibar has been regularly affected by cholera outbreaks. Around 200 to 1,100 cases are reported annually from a population of about 1.2 million despite intensive control measures in place, particularly health education and improved case management. Recently, a major cholera outbreak in Zimbabwe, which borders Tanzania to the southwest, has resulted in at least 4,200 deaths since last August.

Zanzibar, one of the poorest areas of the world, has benefited from growing tourist income from international tourism, and the government fears that repeated cholera outbreaks could have a negative impact on tourism and damage the island´s reputation. Efforts are underway to improve access to safe water and proper sanitation for the long-term control of cholera and other enteric diseases. “But the government is eager to use mass oral cholera vaccination (OCV) as a potential near-term solution to this pressing problem,” said Dr. Jacqueline Deen, the senior IVI research scientist in charge of the project.

The Zanzibar project aims to answer questions about the vaccine’s effectiveness, how long protection lasts, and the extent to which it protects the entire community, including the unvaccinated (“herd protection”). The project also aims to strengthen the country’s integrated disease surveillance and response (IDSR) system; evaluate a new rapid diagnostic test for cholera; and conduct socioeconomic and behavioral studies to understand the perceptions of communities and stakeholders about cholera and the use of oral cholera vaccines.