First Minister Mark Drakeford says the Welsh Government is looking "very carefully" at a national lockdown that would last weeks, not months.
A decision on the circuit-breaker is expected on Monday.
Professor Drakeford added that such measures would be a "short, sharp shock to all our lives" to slow the spread of the virus in Wales.
He said the country faces a "very serious situation" as the number of confirmed cases continue to rise rapidly.
"Unless we are able to get coronavirus back under control, there is a real risk our NHS will be overwhelmed.
"We all need to act together to keep the levels down over the winter ahead."
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