Originally published in The Lancet and authored by Jeannot Francis.
Because of the significant decrease in the incidence of cholera in Haiti in recent years, there has been a tendency among public health agencies to lower guards and become increasingly complacent about prevention measures. In April, 2019, during an evaluation meeting with technical and financial partners in cholera control, officials at the Ministry of Health in Haiti celebrated the low number of reported cases and fatalities as a victory. However, cholera is still a major public health problem in the country: there are an increasing number of unreported cases due to a poor surveillance system, and there is a risk of disease resurgence.
In a modelling study in The Lancet Global Health, Elizabeth Lee and colleagues estimate the health impacts of various cholera vaccination campaign scenarios in Haiti using simulations from four modelling teams. They find that there is a low probability of cholera elimination if the current situation is maintained (no vaccination), and that, among the vaccination campaigns assessed, only nationwide campaigns had a high probability of elimination. This report highlights the need to remain vigilant in the fight against cholera, and could be used to mobilise stakeholders, particularly at the global level, where vaccine supply constraints and difficulties in mobilising funds remain an issue. The report could also help to reactivate the UN’s promise of a trust fund to compensate those affected and help in the elimination process (given the role of the organisation in the introduction of cholera to Haiti),2 the follow-up of which has been inconsistent while the country has faced serious financial challenges in its efforts to combat the disease.
Since the development and large-scale production of new vaccines, cholera has become a vaccine-preventable disease and vaccination has become a tool in cholera control and elimination plans in several countries worldwide. Lee and colleagues provide important information about how a vaccination campaign can fit within a plan to eliminate cholera in an individual country—something that has not been achieved in modern times, and on which more research needs to be conducted. Despite limited effectiveness, the cholera vaccine is safe, and working on a proof-of-concept strategy for cholera elimination with vaccination at the forefront may therefore be worthwhile.
Implementation of the strategy to improve water, sanitation, and hygiene (WASH) has been very slow in Haiti. According to the World Bank, the proportion of Haitians who benefitted from basic water and sanitation facilities decreased from 62% in 1990 to 52% in 2015; over the same period, the sanitation level in urban areas declined by 3%.3 Even in 2020, clean water and sanitation are still a major problem. Since the beginning of the outbreak in Haiti, there have been competing views about ways to control and ultimately eliminate cholera on the island of Hispaniola, with some viewing WASH and vaccination approaches as mutually exclusive. Therefore, one key question that needs to be addressed is how WASH, natural immunity, and past vaccination each contribute to the decreasing incidence of cholera in the country. This would help to indicate best practices in the elimination process moving forward.
From a global public health perspective, implementation of WASH activities is often slow in low-income and middle-income countries because it is an intervention that goes beyond the scope of public health actors. It is therefore important to show the impact of vaccination as a new effective and safe tool to fight cholera in these countries and to set WASH metrics as long-term goals. Lee and colleagues show that elimination of cholera on the island of Hispaniola is feasible even in the context of slow implementation of the WASH strategy. However, despite the substantial decrease in incidence in recent years, it will be important to maintain focus on prevention measures because of the health risks associated with the endemic circulation of Vibrio cholerae and the possibility of resurgence of the disease, which has already taken a heavy toll on the life and wellbeing of the Haitian population, particularly among the most vulnerable sectors.