The world is facing an unprecedented rise in cholera cases, with widespread outbreaks reported in Haiti, Syria and Malawi, and cases detected in 26 other countries this year. In response, the International Coordinating Group (ICG), which manages where and when the cholera vaccine stockpile is used, announced this week a temporary switch to using a single dose of oral cholera vaccine, instead of the usual two. This will allow supplies to go further and ensure that all countries that need vaccines have access to them.
The global increase in cholera cases is linked to disruptions in the supply of drinking water and sanitation, due to extreme weather events such as floods and droughts, conflicts and population displacements.
The decision of the group, made up of the World Health Organization (WHO), Doctors Without Borders (MSF), UNICEF and the International Federation of Red Cross and Red Crescent Societies (IFRC) , comes as the world witnesses a worrying rise in cholera. cases, building on trends that started last year. Droughts, floods and armed conflicts add fuel to the fire.
The Global Cholera Vaccine Stockpile, which is fully funded by Gavi, is designed to provide emergency supplies of vaccines to countries experiencing outbreaks and, where possible, to provide doses for preventive control measures in epidemic-prone areas. The stockpile of cholera vaccines is set at five million doses, which the ICG considers an appropriate level to respond to emergencies. Fortunately, thanks to the vaccine supplies we have, the ICG was able to send vaccines to all the countries that requested them for the outbreak response this year. However, demand is such that more than 80% of global supply is expected to be used for outbreaks this year, meaning prevention campaigns will be delayed.
As countries increasingly seek to use the vaccine preventively to avoid outbreaks, alongside the large simultaneous outbreaks we are currently experiencing, it is clear that more doses will be needed. Work is already underway to increase supply from current manufacturers and help new suppliers enter the cholera vaccine market with significant supply.
Tackling drinking water and sanitation as well as vaccination
The increase in cholera cases is worrying. So far, 29 countries have reported cases in 2022, including Haiti, which had no cases in the previous three years. In comparison, less than 20 countries reported cases each year in the previous five years. The ongoing outbreaks in Syria, Pakistan and Nigeria, where health systems have limited response capacity due to conflict or other emergencies, are of great concern, which risks further spreading the disease in the region.
Cholera is an acute diarrheal infection caused by ingesting food or water contaminated with the bacteria Vibrio cholerae. The global increase in cholera cases is linked to disruptions in the supply of drinking water and sanitation, due to extreme weather events such as floods and droughts, conflicts and population displacements. Rapid urbanization has also fueled its spread, as increasing numbers of people congregate in areas lacking adequate water, hygiene and sanitation.
As helpful as cholera vaccines are, additional public health measures such as improving access to clean water and sanitation, and improving access to basic health care , are needed to stop the emergence and spread of this disease. The goal, ultimately, must be to reduce the factors that make cholera outbreaks likely, which will reduce the number of cases requiring emergency response and, therefore, the pressure on vaccine supplies in general.
Prevention gains ground
Since the stockpiling of cholera vaccines, 120 million doses of oral cholera vaccine have been shipped to 23 countries. Over the past five years, momentum for the use of the oral preventive cholera vaccine has increased dramatically, with half of the global supply (47 million doses) being used for prevention between 2017 and 2021.
Several major countries, including Ethiopia, the Democratic Republic of the Congo (DRC) and Nigeria, have developed or are developing five-year plans for preventive vaccination in areas most at risk of cholera as part of a multi-sectoral national program of long-term cholera control. control planes. Once countries are able to roll out preventive vaccination, we expect outbreaks to be fewer and smaller.
It will still take time for these plans to materialize and for manufacturers to increase their production capacity.
Increase vaccine supply
The ICG’s decision is based on a recommendation from WHO’s Strategic Advisory Group of Experts on Immunization to consider the use of a single-dose strategy in response to outbreaks, as a cost-saving strategy. dose. A single dose of oral cholera vaccine is very effective in preventing infection in the months following vaccination. However, the evidence on how long this protection lasts is limited, meaning that an additional dose may be needed to provide longer-term protection if the risk of cholera persists.
This means we need a greater supply of cholera vaccines. To ensure this happens, Gavi and partners are updating the Cholera Vaccine Market Development Roadmap, which outlines a plan to increase the availability of the oral cholera vaccine globally. and create more stable demand, which should contribute to a healthier vaccine market.
In 2023, Gavi will also begin accepting applications for preventive vaccination plans to prevent long-term outbreaks. COVID-19 has prompted the need to build vaccine manufacturing capacity in Africa to ensure the sustainability of vaccine supply, and cholera is one such vaccine that would greatly benefit, marking a step towards a safer increased global health.