A shortage of cholera vaccines has forced a temporary shift from the usual two-dose strategy in campaigns to combat an increasing number of outbreaks, according to the World Health Organization (WHO).
The International Coordinating Group (ICG), which manages emergency vaccine supplies, was forced to suspend the two-dose regimen due to a “strained global supply of cholera vaccines,” according to the UN health agency.
“The pivot in strategy will allow for the doses to be used in more countries, at a time of unprecedented rise in cholera outbreaks worldwide,” WHO said in a statement.
It pointed out that 29 countries had reported cholera cases so far this year, including Haiti, Syria and Malawi.
That compares with the fewer than 20 nations that reported such outbreaks in total over the previous five years.
“The global trend is moving towards 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,” it said.
Cholera is an acute diarrhoeal infection in the small intestine causing sometimes fatal dehydration. It is generally contracted from food or water contaminated with vibrio cholera bacteria.
WHO and other members of the ICG — the Doctors Without Borders (MSF) charity, the UN children’s agency UNICEF and the Red Cross — highlighted that a one-dose strategy for cholera vaccines had been proven to be effective in response to outbreaks.
But they warned that there was only limited evidence on the exact duration of protection, which appeared to be much lower in children especially.
With two doses, when the second dose is given within six months of the first, immunity against infection lasts for three years.
“The benefit of supplying one dose still outweighs no doses,” Wednesday’s statement said.
“Although the temporary interruption of the two-dose strategy will lead to a reduction and 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 warned that the current supply of cholera vaccines was “extremely limited”.
ICG manages a global stockpile of oral cholera vaccines, but of the 36 million doses forecast to be produced this year, 24 million have already been shipped for preventive and reactive campaigns.
And an additional eight million doses have been approved by ICG for a second round of emergency vaccination in four countries.
“As vaccine manufactures are producing at their maximum current capacity, there is no short-term solution to increase production,” the statement said.
“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.”
WHO warned that this was only a short-term solution.
“To ease the problem in the longer term, urgent action is needed to increase global vaccine production.”