The coronavirus has reached Bangladesh’s Rohingya refugee camps. Now, weeks of preparation will be put to the test as aid responders dive into uncharted territory: containing and treating a pandemic in a refugee camp.

The first two COVID-19 cases – a Rohingya refugee and a Bangladeshi from the surrounding community – were confirmed on 14 May. Epidemiologists fear the virus could tear through the sprawling settlements, home to roughly 900,000 people living in bamboo and tarpaulin tents.

The UN’s refugee agency, UNHCR, said investigation teams had been deployed to isolate the patients, and to trace and test contacts. So far, there has only been minimal testing – only 145 people had been tested as of 15 May – which could slow containment plans. With such low testing numbers, the true reach of the outbreak remains uncertain.