OCV campaign in Guinea shows vaccination can be done - even during an outbreak
Ever since the first oral cholera vaccines (OCVs) appeared on the global market in 1991, many in the international health community have been skeptical about its use to control an ongoing outbreak. A major argument against reactive cholera vaccination – vaccination in response to an outbreak – was that most countries experiencing cholera outbreaks could not successfully mount vaccination campaigns quickly and that the campaign would divert time, effort and resources from more effective and longer-term measures for controlling cholera, such as improvements in water and sanitation and health education.
The logistical challenges posed by Dukoral® – the first licensed OCV – included its two-dose regimen separated by one to six weeks, the need to mix the vaccine with a buffer and clean water, and large cold storage requirements required by its bulky packaging. Even if the logistical challenges were overcome, it was argued that, with the peak of a typical cholera outbreak over within three to four weeks, the vaccination campaign would have little impact, especially if protection starts only after the second dose. However, long-lasting outbreaks over several months in places like Zimbabwe and Haiti in recent years have largely negated this argument.
For these reasons, health agencies had generally considered OCV for pre-emptive vaccination (to prevent outbreaks in the first place) rather than for reactive vaccination. This remained the case even with the licensure in 2009 and pre-qualification in 2011 of the more field-friendly Shanchol™ vaccine, which does not require a buffer or mixing with water, and is less expensive. A 2010 WHO Position Paper on the potential role of OCV  focused mainly on pre-emptive vaccination and was hesitant to fully recommend reactive vaccination due to a lack of data:
“Given the recent large and prolonged outbreaks of cholera (for example in Angola and Zimbabwe), reactive vaccination could be considered by local health authorities as an additional control measure, depending on the local infrastructure and following a thorough investigation of the current and historical epidemiological situation, and clear identification of geographical areas to be targeted…”
However, new data now support the use of reactive vaccination with OCV. The recent experience with reactive cholera vaccination to curtail an outbreak in the West African nation of Guinea, and a series of studies [2,4] that accompanied it, strengthen the case for the use of OCVs during outbreaks (hopefully very early in the outbreak) and provides reassurance of its feasibility and effectiveness during such an emergency. This is the first time that Shanchol™ has been used in response to a cholera outbreak.
More than 140,000 people in living in remote, coastal areas of Guinea received both doses of the vaccine – for an estimated coverage rate of 76%  – demonstrating the feasibility of delivering a two-dose vaccine in rural Africa. Clearly, people desired the vaccine as the coverage rate was high, even among adults who are often reluctant or unable to find the time to take vaccines . The high coverage is even more impressive since no broadcast or mass media were used to inform the public. The messages were spread entirely by personal contacts (by health promoters, village leaders and outreach workers) a few days before the vaccination campaign in each community.
The Guinea campaigns also provide the first data on the effectiveness of Shanchol™ as part of an integrated response to a cholera outbreak. A case-control study, recently published in the New England Journal of Medicine  and involving 40 cases and 160 controls found the vaccine to be 87 percent effective during the first five months following vaccination.
The findings of the Guinea experience demonstrate the ability of health systems in cholera-affected countries, with assistance from partners like Medicine sans Frontieres (MSF), Epicentre and WHO, to conduct high-quality research during a cholera outbreak. They also bode well for the use of OCV through the WHO’s global OCV stockpile created in 2013 , which, as of July 2014, is being expanded and supported by GAVI.
1. Cholera vaccines: WHO position paper. Wkly Epidemiol Rec 85: 117-128 (2010).
2. Luquero FJ, Grout L, Ciglenecki I, Sakoba K, Traore B, et al. (2013) First outbreak response using an oral cholera vaccine in Africa: vaccine coverage, acceptability and surveillance of adverse events, Guinea, 2012. PLoS Negl Trop Dis 7: e2465.
3. Schaetti C, Ali SM, Hutubessy R, Khatib AM, Chaignat CL, Weiss MG. Social and cultural determinants of oral cholera vaccine uptake in Zanzibar. Human Vaccines & Immunotherapeutics 2012; 8:1223 - 1229.
4. Luquero FJ, Grout L, Ciglenecki I, Sakoba K, Traore B, et al. (2014) Use of Vibrio cholerae vaccine in an outbreak in Guinea. N Engl J Med 370: 2111-2120.
5. Martin S, Costa A, Perea W (2012) Stockpiling oral cholera vaccine. Bull World Health Organ 90: 714.