The WHO’s recommendations are targeted at countries facing large outbreaks such as Haiti, Malawi and Syria - with fears that outbreaks could become more widespread with climate change.
'An unwelcome comeback'
There are three WHO pre-qualified oral cholera vaccines: Dukoral, Shanchol, and Euvichol. All three vaccines require two doses for full protection (children aged 2-5 normally require a third dose).
Vaccination campaigns are implemented in areas experiencing an outbreak; those with heightened vulnerability during humanitarian crises; and among populations living in ‘hotspot’ highly endemic areas.
Since the start of this year, 29 countries have reported cholera cases (in comparison, in the previous 5 years, fewer than 20 countries on average reported outbreaks).
Cholera is an acute diarrhoeal infection caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae. The WHO expects to see more numerous, more widespread and more severe outbreaks: due to floods, droughts, conflict, population movements and other factors that limit access to clean water and raise the risk of cholera outbreaks.
As WHO Director-General Dr Tedros Adhanom Ghebreyesus put it in a briefing earlier this month, 'cholera thrives on poverty and conflict but is now being turbocharged by climate change’.
“Extreme climate events like floods, cyclones and droughts further reduce access to clean water and create the ideal environment for cholera to spread,” he said.
He warned that cholera is making ‘an unwelcome comeback’: with the average case fatality rate more than three times that of the last five years. In Syria, more than 10,000 suspected cases of cholera were reported over the most recent six week period.
'The one-dose strategy has proven to be effective to respond to outbreaks, even though evidence on the exact duration of protection is limited, and protection appears to be much lower in children. With a two-dose regimen [0, 6 months] immunity lasts 3 years.
'The benefit of one dose still outweighs no doses. Although the temporary interruption of the two-dose strategy will lead to a reduction & shortening of immunity, this decision will allow more people to be vaccinated and provide them protection in the near term, should the global cholera situation continue deteriorating.' - WHO
“In 2013, WHO and our partners created an international stockpile of cholera vaccines which last year shipped 27 million doses but, with an increasing number of outbreaks, supply cannot keep up with demand," he said.
"We urge the world’s leading vaccine manufacturers to talk to us about how we can increase production."
Supply restraints
The current supply of cholera vaccines is ‘extremely limited,’ notes the organization.
“Its use for emergency response is coordinated by the ICG [International Coordinating Group] which manages the global stockpile of oral cholera vaccines.
"Of the total 36 million doses forecast to be produced in 2022, 24 million have already been shipped for preventive (17%) and reactive (83%) campaigns and an additional 8 million doses were approved by the ICG for the second round for emergency vaccination in 4 countries, illustrating the dire shortage of the vaccine.
"As vaccine manufactures are producing at their maximum current capacity, there is no short-term solution to increase production.
"The temporary suspension of the two-dose strategy will allow the remaining doses to be redirected for any needs for the rest of the year.
“This is a short-term solution but to ease the problem in the longer term, urgent action is needed to increase global vaccine production.”
An estimated 1.3–4.0 million cases of cholera and 21,000–143,000 deaths occur worldwide each year.
South Korea’s EU Biologics produces Euvichol and is the largest supplier of cholera vaccine in the world, representing more than an 80% market share and the ability to produce up to 50 million doses after expansion of its facilities is completed this year.
But Shantha Biotechnics – a wholly-owned Indian subsidiary of Sanofi – has said it will stop producing Shanchol by the end of 2023: putting a dent in supply.
A Sanofi spokesperson told us that 'the current shortage of cholera vaccine is due to an increase in reported cases and not to a discontinuation of vaccine production by Sanofi, as we currently continue to deliver doses of Shanchol vaccine.'
Valneva's Dukoral is primarily used as a travel vaccine with approvals in the EU, Australia, Canada, Switzerland, New Zealand and Thailand.
"In 2020, Sanofi informed its partners, including the WHO, of its intention to stop production of this vaccine by 2023 due to the limited number of doses produced each year and the fact that other manufacturers had announced an increase in their production capacity.
"Sanofi also signed a transfer of knowledge agreement, including intellectual property rights, with International Vaccines Institute (IVI) to facilitate the entry of new vaccine manufacturers to address future needs."