The second-largest cholera vaccination programme in history has achieved a milestone in Bangladesh.

The Ministry of Health and Family Welfare has immunised 700,000 Rohingya refugees in less than a month.

They're particularly at risk because their squalid camps provide the perfect conditions for a cholera outbreak. With Yemen already facing an unprecedented epidemic, government officials hope to avoid a similar situation in the camps near neighbouring Myanmar.

Al Jazeera's Charlotte Bellis reports.