UN says 900,000 doses of oral vaccine are to be given to Rohingya Muslims fleeing violence in neighboring Myanmar.
"A massive cholera immunization campaign started today near Cox’s Bazar, Bangladesh, to protect newly arrived Rohingya and host communities from the life-threatening diarrheal disease," UN said in a statement on Tuesday.
"900,000 doses of the vaccine have been mobilized and are being delivered by more than 200 mobile vaccination teams, making it the second largest oral cholera vaccination campaign ever," UN said.
The campaign is being led by the Ministry of Health of Bangladesh and supported by the World Health Organization (WHO) and UNICEF.
There has been no cholera cases so far among Rohingya refugees in Bangladesh, the WHO said.
According to UNICEF, it is the second largest oral vaccination campaign in the world after Haiti in 2016.
"In the last week, at least 10,292 cases of diarrhea have been reported and treated from across the settlements and camps. The WHO has warned of the potential for an outbreak of cholera," the UN said.
The refugees are fleeing a military operation in Myanmar amid which security forces and Buddhist mobs have killed men, women and children, looted homes and torched Rohingya villages.
Since Aug. 25, when the military launched a crackdown against Rohingya militants, 519,000 Rohingya have crossed from Myanmar's western state of Rakhine into Bangladesh, according to the UN.
It is "the largest and speediest" movement of a civilian population in Asia since the 1970s, the UN said.