PAHO, WHO and other organizations will be watching the program closely to see if the logistics of distribution pan out. "It needs to be verified in the field," says Andrea Vicari, a vaccination advisor at PAHO, of the vaccine program, explaining that although it has worked well in clinical trials and previous assays in Asia, on the ground in Haiti it might prove less effective because of gaps in distribution and people not taking both doses. Vicari plans to visit Haiti to assess the situation at the end of the month. Success could mean a green light for the rest of the country—and likely the world—to use these vaccines on a larger scale to provide immunity where cholera is endemic.
And PIH is eager to show results. "The most immediate data we will have will be completion-rate data: Can we get two doses to the majority of the population we're targeting," says Jonathan Weigel, a researcher at PIH. "We're not worried about whether it will be a safe or effective vaccine—we know it is. That data on completion rate will convince any skeptics about whether it can be rolled out on a wider scale in Haiti."
The lack of access to clean water and proper sanitation facilities means that "we have to consider nearly everybody at risk in Haiti for developing cholera," David Olson, Doctors Without Borders medical advisor for diarrheal diseases, said in a prepared statement.
Therein lies one of the major reasons why, as Vicari notes, there is not yet "a consensus whether the vaccine can be useful or not." Haiti's population far exceeds the current manufacturing capacity of five million doses combined of Shanchol and Dukoral. To vaccinate the entire country with the required two doses per person, it would either take a five-year effort (with immunity waning in each person after two years) or there would need to be a massive scale-up effort in production. "Regardless of financial issues, that is going to be a little bit of a bottleneck," Vicari says.
As Olson pointed out, a strategic use of the limited quantities of vaccine could be workable: vaccines could first be sent to remote regions, where deliveries of soap, clean water and training are more difficult. "It won't be easy to vaccinate in rural areas with poor access, but it would be even harder to intervene should an outbreak occur," Olson said. But not everyone agrees on an appropriate use of the limited supply. Early on in the epidemic, the then-Haitian health minister even expressed concern that having a limited number of doses could cause unrest.
PIH has eliminated that issue from their program by servicing two areas that each has about 50,000 residents, "so we can vaccinate almost everyone in those areas," Weigel explains, who also notes that unvaccinated individuals in these communities would benefit from herd immunity.
Farmer predicts that if the government decides to support the vaccine's more widespread distribution, supply will follow and thereby render the current debate irrelevant. "There are hundreds of thousands of cases just in Haiti—and millions around the world, so if demand were in any way related to burden of disease," there should be adequate supply, he says.
Excising the endemic
Even if the vaccine demonstration proves successful in Bocozel and Cité de Dieu, the cholera scourge is not going to be rid from Haiti with immunization alone. As Weigel is quick to point out, "it would be foolhardy" to try to eradicate cholera from the area using only a vaccine.