A senior doctor at Aneurin Bevan University Health Board has warned the area is seeing "the same pattern as was seen in Italy."
Dr Sarah Aitken, Director of Public Health, said the "rapidly rising" number of coronavirus cases meant the health service could soon become "overwhelmed".
She urged people to stay at home to give the health board "essential time" to bring more doctors and nurses into the workforce, as well as extra ventilators and additional intensive care beds.
There are now 309 confirmed cases of coronavirus in the Aneurin Bevan health board area, nearly half of the total number of cases in Wales.
In a video shared on social media, Dr Aitken said: "In Gwent, we are seeing a rapidly rising increase in the number of cases of coronavirus in all our communities and a daily increase in the number of people being admitted to hospital and the number of people dying from the virus."
The health board has since announced it has suspended all visiting to its hospitals to reduce the spread of coronavirus and to "protect patients and staff".
Dr Aitken added: "The pattern we are seeing in Gwent is the same pattern as was seen in Italy, where their healthcare system is now overwhelmed.
"Without a huge effort by all of us, we are heading for the moment in Gwent where our NHS will be overwhelmed too.
"We won't have enough hospital beds for everyone who needs lifesaving ventilators and intensive care."
22 people have now died of coronavirus in Wales, and there have been 628 confirmed cases.
Public Health Wales said the true number of people infected with the virus is likely to be higher.
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