Doctors Without Borders (MSF) has called for the immediate evacuation of migrant camps on Greece's islands, arguing that the conditions there provide "the perfect storm" for a COVID-19 outbreak.
No-one there has tested positive but the unhygienic and cramped living conditions mean the virus can spread very fast.
MSF laments that there are no epidemic response plans in place.
"In some parts of Moria camp, there is just one water tap for every 1,300 people and no soap available. Families of five or six have to sleep in spaces of no more than 3 m2," MSF's Medical Coordinator in Greece, Dr Hilde Vochten stated.
That makes it almost impossible for those living there to follow recommended measures, such as frequent hand washing and social distancing.
No option but to live in close proximity
Nations worldwide are prohibiting large gatherings, yet people in these camps have nowhere to go.
Dr Vochten added that "it would be impossible to contain an outbreak" in camps on Lesbos, Kos and other islands.
MSF stated on its website on Thursday that setting up migrants in those camps was "always irresponsible," warning that in case of an outbreak this was "on the verge of becoming criminal."
More than 42,000 people are housed in camps on five Greek islands, according to MSF.
Greek PM Kyriakos Mitsotakis said in a cabinet meeting that the country's islands are already "overburdened with public health issues" and must be "doubly protected."
He also promised to do "whatever it takes" to prevent the virus from getting to the islands.
Correction: In an earlier version of this article, we inaccurately reported one person had tested positive for COVID-19. MSF in Greece has clarified that no-one on the camp has tested positive.