Climate emergency multiplies cholera epidemics while vaccines are in short supply

The world is experiencing an emergency of cholera outbreaks never seen since there were vaccines. In 2022 alone, this disease has emerged in 30 countries compared to an annual average of 20 epidemics in the last five years, as warned by the World Health Organization (WHO), which also highlights that the fatality has tripled. The causes are multiple, but researchers and experts agree that the global increase in temperatures due to climate change plays a fundamental role in the intensification of cholera cases, together with forced migration and conflicts. All this is taking place in a context of vaccine shortages, which has made it necessary to reduce the doses administered in these outbreaks from two to one.

“The global increase in temperatures and extreme weather events favor the reproduction of the bacillus that causes cholera. Droughts reduce water sources and increase the risk of contamination, while floods destroy drainage systems, which benefits contagion. If you add climate migration and conflicts to that, we are facing the perfect storm, with millions of people living in displacement camps, with limited access to health and poor sanitation conditions,” says Miriam Alia, head of vaccination and response. to epidemics by Doctors Without Borders (MSF).

Cholera is an old acquaintance of Humanity, an acute diarrheal disease caused by the ingestion of food and especially water contaminated with the Vibrio cholerae bacillus. Currently endemic in 47 countries around the world, the least developed, where sanitation and hygiene systems are more precarious, it is capable of killing in just four hours. It has a fatality rate of up to 50% without access to treatment, basically oral or intravenous hydration for more serious cases, but which is reduced to 1% if there is early detection and health care. The best news is that there is a vaccine and that it is relatively easy to manage.

[El colera] It has a case fatality rate of up to 50% without access to treatment, basically oral or intravenous hydration for more serious cases, but it is reduced to 1% if there is early detection and health care.

Haiti is one of the affected countries. The outbreak began at the end of September and has already reached a hundred deaths and practically 10,000 cases, with a large focus in the capital, Port-au-Prince. The rate of expansion is alarming. Cholera had not been present in Syria for 15 years, but last September it reappeared with force, reaching 13,000 cases and 60 deaths. In Malawi it is much more lethal: the outbreak has spread to all 29 districts of the country, causing 10,300 cases and 300 deaths. At its origin is the passage of tropical storm Ana and cyclone Gombe, in January and March of this year, which caused extensive flooding and the displacement of thousands of people who now have little access to water, sanitation and adequate hygiene conditions. . Lebanon, Kenya, Nigeria or Bangladesh are other countries with active epidemics.

Last October, Tedros Adhanom Ghebreyesus, director of the WHO, issued the alert: “We are not only seeing more outbreaks, but more deadly outbreaks. The data that we have, which is limited, shows that the average case fatality rate so far this year is almost triple that of the last five years.” In his opinion, there is no doubt: “Extreme weather events, such as floods, cyclones and droughts, further reduce access to drinking water and create the ideal environment for the spread of cholera.” This disease, he added, “feeds on poverty and conflict, but is now being fueled by climate change.”

Extreme weather events such as floods, cyclones and droughts further reduce access to safe drinking water and create the ideal environment for the spread of cholera

Tedros Adhanom Ghebreyesus, Director of the WHO

The cholera vaccine “is oral, like the polio vaccine, and can last up to 14 days outside the cold chain,” says Alia. However, the current production for both preventive needs and for active outbreaks is not enough. In 2022, it was planned to produce some 36 million doses, most of them for the so-called reactive or preventive vaccination. However, the “unprecedented” appearance (according to the WHO) of outbreaks in some thirty countries has forced more doses to be allocated to emergencies. For this reason, on October 19, the International Coordination Group (ICG), which coordinates this immunization, decided to reduce the response doses to epidemics from two to one, which reduces the immunity time. “The one-dose strategy has been shown to be effective in responding to outbreaks, although the evidence on the exact duration of protection is limited. It seems to be much lower in children”, says the ICG.

Virtually all production of cholera vaccines is concentrated in two factories located in India and South Korea, but they are at the limit of their capacity. “We are not going to have an increase in manufacturing for at least the next two years and the stock current is not enough”, explains Alia, who insists that, in any case, preventive vaccination is only one pillar of the fight against this disease, “the cheapest and most effective”, but it must be accompanied by measures such as improving sanitation systems. Some countries that planned to immunize their population at risk have had to delay these plans to address outbreaks, such as Nigeria, Cameroon or the Democratic Republic of the Congo (DRC).

The emergence of epidemics due to climate change represents a serious setback for the strategy defined by the Global Task Force on Cholera Control (GTFCC), whose objective was to reduce cases by 90% in the year 2030 through preventive vaccination in the 47 countries where this disease is endemic. More than half of the production went to three African countries, Ethiopia, Nigeria and the DRC, which are now turning their efforts into dealing with the emergency.

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