Geneva (AFP) - A shortage of cholera vaccines has prompted the World Health Organization to reduce the two recommended doses to one dose due to increased demand resulting from the emergence of several foci of the disease in the world, the organization announced Wednesday.

"This change in strategy will allow doses to be provided to more than one country at a time when there is an unprecedented rise in the number of foci in the world," wrote the organization, which participates in the international coordination group in charge of distributing vaccines on an emergency basis.

Since January this year, 29 countries have reported cases of cholera, including Haiti, Malawi and Syria, which is facing an outbreak of the disease.

It is an exceptional situation, as the Health Organization stated that "during the past five years, less than twenty countries recorded an average increase in cases."

The organization estimates that cholera hotspots are "increasing in number and becoming more widespread and dangerous" because of floods and droughts, but also because of population movements or other factors that limit access to clean water and increase the risk of an epidemic spread.

Cholera is usually transmitted through contaminated food or water and causes diarrhea and vomiting.

A safe drinking water supply and sanitation facilities are essential to prevent its spread.

The World Health Organization considers that the "single-dose strategy has been shown to be effective" while acknowledging that there is a lack of precise duration of protection with the single-dose regimen and that protection appears to be weaker in children.

"With the two-dose regimen, when the second dose is given six months after the first dose, immunity to the disease lasts three years," the WHO said.

But she believes that "the benefit of giving a dose is always greater than taking no dose."

And the organization adds that "although the temporary cessation of the two-dose strategy leads to a decrease in immunity and a shortening of its duration, this decision will allow vaccinating a larger number of people and ensuring short-term protection for them, if the global cholera situation continues to deteriorate."

Stocks of cholera vaccines are very limited at the moment. Of the 36 million doses that are supposed to be produced in 2022, 24 million were sent for preventive (17%) and interactive campaigns (83%), and the International Coordination Group approved an additional eight million doses for the second round of emergency vaccination in four countries, as announced by the World Health Organization in a statement .

"Since vaccine manufacturers are currently producing at their maximum capacity, there is no short-term solution to increase production," she added.

One reason for the vaccine shortage is the decision by the Indian vaccine maker, the French subsidiary of Sanofi, to halt production by the end of the year, but it is not the only reason.

Doctors Without Borders, a participant in the international coordination group, says the reasons for the lack of vaccines are multiple.

"This last option is the way to avoid the impossible choice between sending doses to one country instead of another," Dr. Daniela Garoni, the NGO's international medical coordinator, said in a statement.

"One-dose vaccination will provide shorter protection, but it is the fair and equitable way to protect as many people as possible while we face simultaneous cholera epidemics," she added.

However, she stressed, "This solution is temporary, and the current supply shortage is a source of serious concern for any short- and medium-term response needed for new cholera epidemics to emerge this year."