The vaccine shortage comes as southern Africa battles a protracted cholera outbreak which has killed 700 people in Zambia alone.
Medical charity Doctors Without Borders said that the shortage has affected its teams trying to respond to outbreaks in more than 16 countries.
Public health experts have urged manufacturers to speed up the production of the oral vaccine. All drugs currently in production have already been booked.
In January, Zambia rolled out a UNICEF-backed campaign to vaccinate 1.5 million people against cholera. The outbreak which started in 2023 has now spread to all regions of the country, forcing authorities to convert a stadium into a treatment centre and to delay the reopening of schools.
According to Save the Children, cholera cases increased fourfold in Malawi, Zimbabwe, and Mozambique from 2022 to 2023.
The number of infections rose from 26 250 to over 95 300, with more than 1 600 deaths in the three nations, making it one of the worst cholera epidemics in decades.
